MEP Connection For Seismic Zone

structure (12”) to eliminate the need for restraint.
(Refer to the building code review

chapter (D2) to determine if this exemption is applicable.) If it is applicable, the 12”
dimension is measured as shown below.
KINETICS™ Seismic Design Manual

11) When using the above rule it is critical that all support locations in a run conform. If
even one location exceeds 12”, the run cannot be exempted from restraint.
DEFINITIONS AND LOCATING REQUIREMENTS

PAGE 6 OF 6 RELEASE DATE: 11/6/07
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Ceiling-Supported Duct Restraint Arrangements
Although the basic principle of diagonal bracing is almost always used to design restraint
systems, the actual arrangement of these systems can vary significantly. Despite what
looks like substantially different designs, the design forces in the members remain the
same, and the same rules apply when sizing components. Illustrated here are many
different restraint arrangements, all of which can be used in conjunction with the design
“rules” provided in this manual.
Details of the end connections and anchorage hardware are shown in subsequent
sections of the manual. It is assumed in this manual that the restraint component is

attached to a structural element capable of resisting the design seismic load.
Due to variations in the installation conditions such as structural clearance, locations of

structural attachment points, and interference with other pieces of equipment or systems,
there will likely be significant benefits to using different arrangements in different locations
on the same job.
The only significant caution here is that it is not permissible to mix struts and cables on
the same run.
This manual addresses diagonal bracing slopes of between horizontal and 60 degrees
from the horizontal. Angles in excess of 60 degrees to the horizontal are not permitted.
When installing restraints, lateral restraints should be installed perpendicular

( 10 degrees) to the duct in plan. Axial restraints should be in line with the duct,
10 degrees, again in the plan view. All restraint cables should be aligned with each
other. See the sketch below.
CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS


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Lateral Restraint Axial Restraint
In general, when restraining ductwork, the component actually being restrained is the
support device for the duct. This is normally either a ring clamp made of gauge material,
or a trapeze bar. Because the goal is to restrain the actual duct, it is necessary that the
restrained element be connected to the duct in such a way as to transfer the appropriate
forces between the two.
Based on the Maximum Horizontal Force requirement and Force Class from Section D4,
the appropriate size and quantity of fasteners to connect ducts to support/restraint
members is as follows:
Force Class I II III IV V VI

Force (Lbs) 250 500 1000 2000 5000 10000
#10 Screw 3 5 10 20
¼ Screw 3 6 20 40
When firmly connecting restraints to ductwork there are a few general rules that should be
followed:
1) Attachment screws should be spread evenly either around or along the top and bottom
of the duct.
2) To minimize wind noise, short screws with minimal projection into the air stream
should be selected.
3) Trapeze-mounted ductwork must be fully encompassed by a frame or screwed to the
trapeze at each lateral restraint point.
4) Axially restrained duct connections must be positive and require screws as indicated
above.
In addition, when sizing restraint components for multiple ducts, the total weight of all of
the restrained ductwork must be considered.

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Hanging Systems Restrained with Cables
Hanging systems may include supports for single or multiple ducts. Single ducts can be
supported using brackets made of gauge material but multiple pipes are normally
supported on or suspended from trapeze bars.
Lateral Restraint Examples
For a cable-restrained duct supported by gauge brackets, there is really only one
mounting arrangement. It can be used with both isolated and non-isolated systems as
shown below. Note that the isolators are mounted with minimal clearance to the structure

and that a travel limiting washer is fitted to the hanger rod just below the isolator in the
isolated arrangement.
Lateral Cable Restraints used with a Gauge Material Ring Clamp (Non-isolated)
Lateral Cable Restraints used with a Gauge Material Ring Clamp (Isolated)
There are many options that exist for the arrangements of lateral restraints used in
conjunction with trapeze-mounted systems. Shown below are several options for both
non-isolated and isolated cable-restrained systems.


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\_/ (BOTTOM) \_/ (TOP)
TRAPPED TRAPPED

BOXED BOXED

V (TOP) X (TOP)
BOXED TRAPPED
Lateral Cable Restraints Mounted to a Trapeze (Non-isolated)

TRAPPED TRAPPED

BOXED BOXED

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V (TOP) X (TOP)
BOXED TRAPPED
Lateral Cable Restraints Mounted to a Trapeze (Isolated)

Axial Restraint Examples
When axially restraining ductwork, a perimeter metal strap or angle tightly screwed to the
duct is the most common device used to retain the duct to the support bar. Occasionally
welded tabs or connections to flanges are used. (Caution: Connections to flanges should
only be used with the flange manufacturer’s concurrence that the flange can withstand the
seismic forces.) Details on these connections will be addressed in later sections.
Axial restraints offset from the centerline of restrained ductwork will generate additional
bending forces in the duct. Because of the nature of ducts, unless restraints are fit on both
sides, there will be an offset. Provisions should be made to avoid offsetting axial
restraints when restraining a single duct. This requires either that the restraint be
attached to the centerline of the duct, that the axial restraint be combined with a lateral
restraint to form an “X” arrangement or that 2 axial restraints be fitted, one on either side
of the duct (See also the Figure below). (Note that when specifying and providing
restraints, KNC assumes one of the 2 former arrangements are used, if the latter case is
used, the installation contractor will have to procure and additional restraint set from
KNC.) For cases where multiple ducts are being supported on a common structure, the
axial restraint should be between ducts in line with the approximate side-to-side center of
Gravity location.
Various Acceptable Axial Restraint Arrangements


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V (BOTTOM)
TRAPPED
V (TOP) GAUGE BRACKET

BOXED

SUPPORTED
Axial Cable Restraints (Non-isolated)
V (BOTTOM)
TRAPPED
V (TOP) GAUGE BRACKET

BOXED SUPPORTED
Axial Cable Restraints (Isolated)
Hanging Systems Restrained with Struts
It is recommended that struts not be used to restrain isolated ductwork. Struts will
generate hard connections between the duct and structure and will greatly reduce the
efficiency of the isolation system. Having said that, in some special situations it may be
possible to design restraint struts with integral isolation elements, but this is tedious and


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should be avoided unless drastic measures are required.
As with cable restraints, hanging systems may include supports for single ducts or
multiple ducts. Single ducts can be supported using a bracket made of gauge material,
but multiple ducts are normally supported on trapeze bars.
For a strut-restrained duct supported by a bracket made from gauge material there is only
one common arrangement. It is to connect the restraint to the base of the hanger rod at
the attachment point to the bracket. It is shown below.

Typical Lateral Restraint Strut Arrangements for Gauge Bracket Supported Duct
Shown below are 3 options for trapeze-supported ductwork. All are equivalent.


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3 Arrangements for Laterally Restrained Trapezes with Struts
When axially restraining ductwork with struts, a perimeter metal strap or angle tightly
screwed to the duct is the most common device used to retain the duct to the support bar.
Occasionally welded tabs or connections to flanges are used. (Caution: Connections to
flanges should only be used with the flange manufacturer’s concurrence that the flange
can withstand the seismic forces.) Details on these connections will be addressed in later
sections.

As with cables, struts offset from the centerline of restrained ductwork will generate
additional bending forces in the duct. Because of the nature of ducts, unless restraints are
fitted on both sides, there will be an offset. Provisions should be made to avoid offsetting
axial restraints when restraining a single duct. This requires either that the restraint be
attached to the centerline of the duct, that the axial restraint be combined with a lateral
of the duct. (Note that when specifying and providing restraints, KNC assumes one of the
2 former arrangements are used, if the latter case is used, the installation contractor will
have to procure and additional restraint set from KNC.) For cases where multiple ducts
are being supported on a common structure, the axial restraint should be between ducts
in line with the approximate side-to-side center of gravity location.
Ignoring the details of the connection at this point, common axial restraint arrangements
recognized in this manual are illustrated below.
Ductwork Axially Restrained with Struts


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Floor- or Roof-Supported Duct Restraint Arrangements
systems, the actual arrangements of these systems can vary significantly. Despite what
look like substantially different designs, the design forces in the members remain the
different floor- and roof-mounted restraint arrangements, all of which can be used in
conjunction with the design “ rules” provided in this manual.
sections of this manual. It is assumed in this manual that the restraint component is
KINETICS ™ Seismic Design Manual

This manual addresses diagonal bracing oriented between horizontal and 60 degrees

(±10 degrees) to the duct in the plan view. Axial restraints should be in line with the duct
(±10 degrees) again in the plan view. All restraint cables should be aligned with each
FLOOR- OR ROOF-SUPPORTED DUCT RESTRAINT ARRANGEMENTS


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Kinetics Noise Control ©2003

In general, when restraining ductwork the component actually being restrained is the
support device for the duct. For floor-mounted equipment this would normally be either a
fabricated frame or a trapeze bar. Because the goal is to restrain the actual duct, it is
necessary that the restrained element be connected to the duct in such a way as to
transfer the appropriate forces between the two.

Force (Lbs) 250 500 1000 2000 5000 10000

#10 Screw 3 5 10 20
¼ Screw 3 6 20 40
followed:
of the duct.
should be selected.
above.
In addition, when sizing restraint components for multiple ducts the total weight of all of
the restrained ductwork must be considered.
Floor- or Roof-mounted Systems Restrained with Cables
Floor- or roof-mounted systems may include supports for single or multiple ducts.
Typically, simple box frames are fabricated to support the ductwork, whether independent
or in groups.
For a cable-restrained duct support bracket there are four options normally encountered
for non-isolated systems and four similar arrangements for isolated systems. These
options are shown below. The vertical legs of the support bracket must be sized to carry
both the weight load of the supported ductwork as well as the vertical component of the
seismic forces. Refer to Chapter D4 for more detailed information as to how to size these
members.

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OUTSIDE RESTRAINT
X-BRACED INSIDE RESTRAINTS

Lateral Cable Restraints used in conjunction with Floor-Mounted Duct Support
Stands (Non-isolated)
OUTSIDE RESTRAINT SINGLE LEG RESTRAINT
X-BRACED INSIDE RESTRAINTS
Lateral Cable Restraints used in conjunction with Floor-Mounted Duct Support

Stands (Isolated)


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only be used with the flange manufacturer’ s concurrence that the flange can withstand the
If the details of the connection are ignored at this point, general axial restraint
arrangements recognized in this manual are illustrated below.
Axial restraints offset from the centerline of restrained ductwork will generate additional

bending forces in the duct. Because of the nature of ducts, unless restraints are fitted on
both sides, there will be an offset. As long as the restraint is immediately adjacent to the
duct, it is permissible to use a single restraint point for axial restraint. For cases where
multiple ducts are being supported on a common structure, the axial restraint should be
between ducts in line with the approximate side-to-side center of gravity location.
RESTRAINED RESTRAINED
DUCT SUPPORT
Axial Cable Restraints (Non-isolated)
DUCT SUPPORT
ISOLATOR ISOLATOR
Axial Cable Restraints (Isolated)


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Floor- or Roof-Mounted Systems Restrained with Struts
As with cable restraints, floor- or roof-mounted duct support systems will normally involve
a box frame that supports the duct (single or multiple) with some kind of a trapeze bar.
Restraint connections directly between an isolated duct and structure using a strut are not
recommended.
With struts there are three typical configurations. As with the cable systems, these
arrangements can be used with or without isolation as shown below.

SIDE RESTRAINT DIAGONAL BRACE
ANCHORED TO STRUCTURAL
WALL ELEMENT
Typical Lateral Restraint Strut Arrangements for Ductwork (Non-isolated)
SIDE RESTRAINT DIAGONAL BRACE

SEISMIC RATED SEISMIC RATED
ISOLATOR ISOLATOR
ANCHORED TO STRUCTURAL
WALL ELEMENT
SEISMIC RATED
ISOLATOR
Typical Lateral Restraint Strut Arrangements for Ductwork (Isolated)


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D8.4.3

only be used with the flange manufacturer’ s concurrence that the flange can withstand the
As with the cable restraints, axial restraints offset from the centerline of restrained

ductwork will generate additional bending forces in the duct. Because of the nature of
ducts, unless restraints are fitted on both sides, there will be an offset. As long as the
restraint is immediately adjacent to the duct, it is permissible to use a single restraint point
for axial restraint. For cases where multiple ducts are being supported on a common
structure, the axial restraint should be between ducts in line with the approximate side-to-
side center of gravity location.
DUCT SUPPORT
Ductwork Axially Restrained with Struts (Non-isolated)
RESTRAINED
SUPPORT
SEISMIC RATED
ISOLATOR
Ductwork Axially Restrained with Struts (Isolated)


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Transferring Forces (Duct Restraints)
In order for a restraint system to do its job, all elements of the connections need to be
sized and installed properly. Because of the large variety and quantity of interfacing
conditions in any given installation, piping, duct, and electrical distribution systems are
particularly prone to problems in this area.
The next several sections of this manual will deal with specific components used to clamp
cable ends together or anchor cables or struts to steel members, wood members, and
concrete or masonry. There are several types of connections used for each of these
conditions, and each type of connection requires some degree of care and understanding

to achieve full capacity.
There are a few general rules that apply when adding restraints to systems. These are
listed below along with a few comments meant to provide a basic understanding or
rationale.
1) Friction generally cannot be counted on when dealing with dynamic, seismic load
conditions. Connections, with the following exceptions, should be positive in nature
and not require friction to ensure their continued long-term operation.
Exceptions:
A) Cable end connections (swaged ends, u-bolts, Gripple clips, and cable nuts can
be used with appropriate installation procedures).
B) Toothed strut nuts used in conjunction with a purpose-designed strut material
(Unistrut, for example).
(Rationale: Permitted friction connections have been well researched and deal with a
narrow range of applications. In addition, once properly tightened, the components
are such that the likelihood of their coming loose as a result of seismic load conditions
is very low.)
2) Anchors used for the support of overhead equipment cannot also be used for the
anchorage of seismic restraints. (Rationale: The loads used to size hanger rods and
anchors are based on the weight loads generated by the piping system. Seismic
forces can increase the tensile loads significantly, and the combination of loads can
cause the anchorage to fail.)
3) Anchors to concrete must comply with minimum edge distance, spacing, and slab
thickness requirements. To achieve full capacity ratings they must further not be
installed into a surface containing significant tensile forces. (Rationale: All anchorage
must be in compliance with ICC allowables for seismic applications. Unless otherwise
noted, it is assumed that connections are not made to the underside of structural
concrete beams.)
4) Screws attached to wood must comply with minimum edge distance, spacing, and
TRANSFERRING FORCES (DUCT RESTRAINTS)


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embedment requirements, and must further not be embedded into the end grain of the
wooden member. (Rationale: All wood anchorage must be in compliance with NDS
allowables for seismic applications. Full capacity can only be achieved with adequate
embedment, end, and edge distances into the side grain of structural wood members.)
5) Connections that have the potential to expose open bar joist chords to significant
lateral loads are not permitted. (Rationale: Open joists are notoriously weak in their
lateral axis. They are not designed to take loads, particularly on the lower cord, and
even light lateral loads can generate buckling and quickly cause catastrophic failure.)
6) Connections that have the potential to generate significant lateral loads on the weak

axis of I-beams or channels used as joists or columns are not permitted unless
approved by the structural engineer of record. (Rationale: Floor or roof support beams
are significantly weaker in their minor axis than in their major axis. While they can,
under some conditions, withstand some lateral loads, the engineer of record should be
consulted to ensure that capacity exists on particular members to withstand the
anticipated loads. If these loads are exceeded, catastrophic failures can quickly
result.)
7) Holes should not be added to key structural members without prior authorization from
the engineer of record. (Rationale: The addition of holes, particularly in flanges, can
greatly reduce the structural capacity.
8) The duct-to-duct connection can become a critical factor in evaluating the performance
of the system. Unless otherwise informed, Kinetics Noise Control assumes
connections to be of “ medium” deformability as defined by the design code. This is
generally appropriate for most types of inter-duct connections including proprietary
flange systems (but this is subject to verification by others). Often it is desired to use
flanges for support or restraint connections in the field. This should not be attempted
without the knowledge and permission of the flange manufacturer. (Rationale: The
magnitude of the forces transferred through these connections during a seismic event
can far exceed those required for normal use and the potential exists for restraint
connections to these flanges to fail causing significant damage to the system.)
TRANSFERRING FORCES (DUCT RESTRAINTS)


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Cable Clamp Details
There are three different types of cable clamp arrangements that are acceptable for use
on Kinetics Noise Control cable restraint systems. These are factory swaged, clamped
with U-bolt cable clips, and connections made using seismically rated “Gripple”
connectors. Other types of connections have either not been tested, or when tested do
not meet the capacity standards required for consistent performance.
Factory-Swaged Connections
When so ordered, one end of a cable assembly can be obtained with a factory-swaged

connection. Crimping a zinc-coated copper or a stainless steel sleeve onto a cable loop
at the termination point makes these connections. Multiple crimp locations are required
with the actual number varying based on the cable size. To obtain a seismic rating, these
swaged connections must be performed using the appropriate calibrated hydraulic press
and must not use aluminum sleeves. Field-swaged connections and in particular those
made using hand crimping tools are not suitable for seismic applications. All Kinetics
Noise Control computed seismic certifications are based on capacities obtained from
components provided by Kinetics Noise Control. No certifications can be offered on
components crimped by others.
Swaged Connector
U-Bolt Cable Clip Connections
For larger cables, as an option to the seismically rated “Gripple”on smaller cables, and
where field connections are necessary or desired, U-bolt cable clips can be used. When
used, a minimum of three clips is required per connection for sizes up to 3/8”cable. For
1/2”cables a minimum of four clips is required per connection.
CABLE CLAMP DETAILS


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SADDLE
CABLE CLIPS
U-Bolt Cable Clips
When fitting cable clips, the saddle side of the clip must always be against the “live”

portion of the cable. The “live”side of the cable is the side that does not terminate at the
connection, but continues to the clip at the opposite end.
CORRECT NOT LIKE

INSTALLATION THIS
Failure to orient the clip in the proper fashion will cause premature failure of the cable
assembly.
While proper tightening of the clip nuts and adequate turnback (or overlap) length of the
cable is important, tests conducted have found that it is not as critical for seismic
applications as it is for lifting applications. Reasonable variations from the values listed
below have a minimal impact on the capacity of the connection. Below is a table with the
desired minimum tightening torques recommended by clip manufacturers, clip quantities,
and turnback lengths listed for various sized cables.
Minimum Minimum
Amount of Rope
Cable Size Number Torque in
Turnback/Inches
in Inches of Clips Ft. Lbs.
1/8 3 3-3/4 3
3/16 3 3-3/4 4.5
1/4 3 4-3/4 15
3/8 3 6-1/2 30
1/2 4 11-1/2 45
CABLE CLAMP DETAILS


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“Gripple” Connections
For smaller cables (up to 5mm (metric) and up to 3/16” (English)), special proprietary
“Gripple”connection clips can be used. These clips offer significant benefits in speed of
installation and can be used in a large variety of common light-duty applications. When
using “Gripple” connectors or “Gripple” restraint connection kits, it is critical that
seismically rated components are used. While Kinetics Noise Control offers only
seismically rated components, those supplied by others may not be. “Gripple”connectors
for sizes in excess of 5mm or 3/16”are not appropriate for seismic installations as they
will not seat properly and consistently without the application of a constant tensile load.

Gripple Connector
GRIPPLE Installation Procedure

1) Feed the proper sized cable as provided by Kinetics Noise Control through the Gripple
as shown.
FEED CABLE THROUGH GRIPPLE

IN DIRECTION OF ARROW
2) Loop the cable through the attachment bracket or hardware. If the cable rides against
any sharp corners (not counting the hole in the Kinetics Noise Control provided
bracket itself) or is subject to excessive vibration in service, fit the Kinetics Noise
Control provided thimble in the loop and then feed the cable back through the opposite
side of the GRIPPLE.
CABLE CLAMP DETAILS


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LOOP CABLE AROUND BRACKET
(INSERT THIMBLE IF CABLE RUBS
ON A SHARP CORNER OR VIBRATION
IS AN ISSUE) AND THEN FEED
CABLE BACK THROUGH GRIPPLE IN
DIRECTION OF ARROW

3) Remove the slack from the cable by slipping the cable through the GRIPPLE, but
leave the loop slightly oversized to allow later tensioning.
STRUCTURAL ATTACHMENT
POINT (ACTUAL HARDARE AND
GEOMETRY CAN VARY FROM
THAT SHOWN)
CONCRETE OR STEEL
STRUCTURE BY OTHERS
DURING INITIAL INSTALLATION EQUIPMENT ATTACHMENT POINT

LEAVE LOOP SLIGHTLY OVERSIZE (ACTUAL HARDWARE AND GEOMETRY
CAN VARY FROM THAT SHOWN)
4) Apply a sideways load to the cable by pulling or pushing on it to fully seat the
GRIPPLE.
PUSH SIDEWAYS ON CABLE

TO SET JAW IN GRIPPLE
CABLE CLAMP DETAILS


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5) When seating the GRIPPLE, jaws will ride up an internal ramp in the GRIPPLE itself
and “bite” into the cable. In a properly seated GRIPPLE, the cable will shift
approximately 1-1/2 cable diameters (the preset distance) as the jaws engage. If need
be, mark the cable to check the preset. This step may be required initially, but once a
“feel”for it is obtained, this is no longer necessary. Once the 1-1/2 cable diameter
preset dimension has been obtained, the GRIPPLE is adequately seated.
APPROX
1-1/2 CABLE
DIA. PRESET

PRESET DIMENSION
MEASUREMENT
LOCATION
6) Once fully seated, any additional slack should be removed from the cable restraint by
pulling on the dead end or “tail”of the cable sticking out of the GRIPPLE. If Isolated,
the cables should not be made tight, but should instead be left slightly loose to prevent
the transfer of vibrations into the structure. (Slightly loose could be defined as having
approx 1/8 to 1/4”of visible sag in the cable – 1/8 for short cables (up to 2 ft), 1/4 for
cables longer than that.)
PULL DEAD END OR "TAIL"

TO REMOVE REMAINING
SLACK FROM CABLE.
7) The GRIPPLE installation is now complete.
CABLE CLAMP DETAILS


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Cable Thimbles
Where sharp corners can bear against the cable loop or where vibration or other dynamic
forces can cause the cable loop to abraid, a cable thimble should be used. A cable
thimble fit inside the cable loop is shown in the picture below.

Cable Thimble
Unacceptable Connectors
Drilled bolt Cable Connections exhibit undesirable inconsistancies in capacity if

precautions are not taken during the assembly process. Undertightening these types of
connections results in a loss of frictional capacity while overtightenting cuts into the cable
and generates premature cable failures.
Unacceptable Cable Connection Detail and Common Application
If used, the only consistant way to properly install cable connectors of this or similar type
is with the use of a torque wrench. Variations of as little as 5 ft-lb of tightening torque can
drop the tensile failure load on the cable by 30% or more. Since the use of torque
wrenches or other torque-controlled devices in the field is limited, the level of confidence
in the capabilities of these connections is lower than desired for critical seismic
CABLE CLAMP DETAILS


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applications.
Because of the extreme sensitivity of the cable pull strength to the tightening torque of the
bolt, drilled cable retention bolts have not been found to be acceptable by Kinetics Noise
Control for use as connection hardware.
CABLE CLAMP DETAILS


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Duct Attachment Details
Ducts can be supported as independent units or grouped together and supported on a
trapeze structure. Restraints can be installed in the same manner. When installing
restraints, however, it is critical that (except for horizontally oriented restraint members)
they be located in the immediate proximity of a vertical support member, as the support is
required to absorb vertical forces that are developed during the restraint process.
If the ductwork is isolated, cable restraints should be used in lieu of struts to prevent the
transfer of vibration through the strut into the structure. Where cables are illustrated, they
can be replaced with a single strut mounted in a similar fashion where appropriate.

Round Duct Sections Supported on Hangers
Lateral Restraints
Single round ducts can be supported with 1 or 2 hanger rods. A single support will
typically connect to a band clamp made of gauge material. A double support will typically
connect to both sides of a split band clamp (2 semicircles) again made of gauge material.
The single hanger rod arrangement can normally be made of a steel strip or a structural
shape rather than from threaded rod where the double support will normally be comprised
of (2) pieces of threaded rod material.
When using the single rod arrangement, restraints should connect to the duct with (3)
similar band clamps oriented as shown below.
Round Duct – Single Support – 3 Band Clamps and Cables
DUCT ATTACHMENT DETAILS


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Round Duct – Single Support – 2 Band Clamps and Strut
When using the double rod arrangement, restraints should connect to the duct at the
support locations, again as shown below.
Large Round Duct with Double Supports and Cable Restraints
Isolated Round Duct with Double Supports


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The above description represents the minimum treatment required at each restraint
location and is appropriate whether cable restraints or struts are used.
Axial Restraints
When connecting ductwork to axially restrained supports, slippage between the duct and
support is typically addressed by screwing the duct to the support bar or to an encircling
band. The diameter and quantity of screws required are directly related to the force that
they much resist.


Force (Lbs) 250 500 1000 2000 5000 10000
#10 Screw 3 5 10 20
¼ Screw 3 6 20 40
Single Support Duct Axially Restrained with Cable
followed:
of the duct.
should be selected.
above.


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Single Support Duct Axially Restrained with a Strut
Restraint Arrangements for Duct Sections Supported on a Trapeze
General Trapeze Design
Ducts can be supported singly or in multiples on trapeze bars. When restraining multiple
ducts of different sizes, the maximum spacing between restraints cannot exceed the
worst-case condition for any of the individual ducts. In addition, the restraints must be
sized based on the total weight of all of the ducts on the trapeze bar. Some caution
should be exercised when selecting the bar to ensure that it has adequate capacity to
transfer the load from the ducts to the restraint connections. This is particularly true for
some strut arrangements that can be significantly stiffer in the vertical axis than they are
in the horizontal (see illustration below.) Because the range of applications for trapeze
bars is limitless, details will not be addressed here, but should be reviewed by a
competent design professional.
Section that is Stiff Vertically

But Weak Horizontally


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Duct Connections to Trapeze Bars
When installing restraints, typically not all support points will require treatment. For those
trapeze bars that are not restrained either axially or laterally, no special connection
treatment is required. Where lateral restraint only is provided at a location, motion
restraint between the duct and the trapeze bar only is required in the lateral direction.
Where axial restraint is required, the duct needs to be screwed firmly to the trapeze bar so
that it cannot slip during a seismic event.
The axial clamps shown here are suitable for both axial and lateral loads, and can be
used on all connections. The lateral restraint examples are only appropriate for lateral
loads.

Connections should not be made to duct flanges without the prior consent of the flange
manufacturer. In general, these are not designed to withstand seismic loads, so without
confirmation that they are adequate, should be ignored when arranging restraints.
Axial/Lateral Restraint Trapeze Connections
Below are examples of connections that would be suitable for either axial or lateral load
conditions.
Various Screwed Duct to Trapeze Arrangements


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Duct Restrained using a Full Perimeter Strap (3” x 12 Ga Min)

Trapeze Connections Suitable for Lateral Restraint Only
In cases where only lateral restraint is needed, it is possible to encase or “ trap” the duct.
The result is a connection similar to those shown above with the inter-connecting screws
omitted.
Trapeze Connections Suitable for Lateral Restraint Only
Cable and Strut Hardware Attachment Options for use with Single
Round Duct Attachment Bands
A typical duct installation begins with suspending the ductwork, and then returning later
and adding restraints. While this eliminates the need to deal with restraints when actually


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hanging the duct, it normally results in more time expended, and possible rework, during
the restraint installation phase. Increasing the diameter of hanger rods for strut-restrained
systems, relocation or duplication of supports for more accessible restraint installation,
and dismantling and reassembling hanger components to make appropriate connections
are the three primary examples of this.
While there is little that can be done from a hardware standpoint to deal with relocation
issues, the proper selection of restraint hardware can reduce or eliminate the need to
dismantle and reassemble previously installed duct supports.
Cable/Strut Restraint Connection Hardware for Hanger Brackets

The CCA mounting clip can be used with either cables or struts, but for struts, the angle
between the strut and the ground is limited to 45 degrees. See the sketches below.
Side-Mounted CCA Clip with Cable and Strut Connections
As an option to the CCA clip, a KSCU clip can be used for side-mounted cable restraint
applications as shown below.
Side-Mounted KSUA Clips with Cable Connections


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While the KSCA is the most versatile clip manufactured by Kinetics Noise Control, it is not
well suited for direct attachment to band-type duct brackets. However, in applications
involving hanger rods (like side-supported duct), it offers the ability to directly connect to
the hanger rod, offering a significant savings in installation time and cost. Shown here is
both an “ inline” arrangement for single axis restraint and a “ V” arrangement where biaxial
restraint is needed.

Hanger Rod-Mounted KSCA Cable Restraint Clip
The KSCA is not suitable for extremely heavy-duty applications. This would encompass
very large ducts in high seismic areas. However, it is appropriate for most applications.
See the tables in Chapter D4 in this manual for sizing components.
Cable/Strut Restraint Connection Hardware for Trapeze Bars
One of the most common materials for trapezed support of ductwork is formed strut-type
channel (ex. Unitstrut). Connections to these materials, if using strut nuts, require the use
of toothed nuts. Smooth nuts do not provide adequate resistance against friction and as
such are not acceptable. All nuts must be tightened to their full-rated torque.
Shown below are various acceptable methods of mounting restraint hardware to struts.


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Cable Restraint Bracket to Strut Trapeze Bar Connections (Typical)
Similar types of mounting arrangements can be used with trapeze bars made out of angle
or other structural shapes as illustrated below.


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Cable Restraint Bracket to Structural Steel Trapeze Bar Connections (Typical)
Hanger Rod Stiffening Arrangements
In some cases, depending on hanger rod length and the applied seismic force, it may be
necessary to protect the hanger rod from the buckling forces that can occur during a
seismic event. Chapter D4 includes a section on determining the need for and sizing of
the stiffener. When required, either a pipe or an angle can be used as a stiffener and
must be clamped tightly to the hanger rod using rod clamps.
Kinetics Noise Control makes clamps for both pipe and angle stiffeners. These are
designated the KSRC-P (for pipe) and KSRC-A (for angle). Both are adjustable and can
be used over a wide range of hanger rod and stiffener sizes.
KSRC-P Hanger Rod Stiffener Clamp can be used to clamp Rods from .5” to 1.0”
Diameter to Pipes from .75” to 1.5” Diameter
Both clamps feature two-part construction and “ no tool required” installation. The KSRC-
P is comprised of a flexible band punched with a number of slots that is fit to a clamp body
with an integral seat for the hanger rod. Based on the size of the pipe stiffener and the
hanger rod, the appropriate slot in the clamp band can be used for preliminary


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adjustment, with final tightening by means of a wing nut.

KSRC-A Hanger Rod Stiffener Clamp can be used to clamp Rods from .5” to 1.0”
Diameter to Angles with Leg lengths from 1 to 2 inches
Shown above is the KSRC-A Clamp. It is made up of two telescoping jaws and a
thumbscrew. Preliminary adjustment is made by aligning the appropriate holes in the
jaws for the thumb screw, and final tightening is made by tightening the screw.
For both of the above clamps the clamping screws are to be tightened so that they will not
come loose in service through vibration. If significant vibration is expected, the use of
Loctite or other thread binder is recommended.


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Structural Attachment Details
for Duct Restraints
When restraining ductwork to a structure, there are several different construction options
that impact the restraint selection. Primary among these are the interface with masonry-
or concrete-, steel-, and wood-framed structures. Within each of these are subgroups that
can impact the restraint selection as well.
This chapter is broken down into the three main categories listed above, and offers
examples of restraint attachment arrangements suitable for each.

While this section addresses local stresses at attachment points, it is critical in any
seismic installation that the design professional responsible for the structure as a whole is
made aware of the particular attachment points. Locations and estimated loads must be
provided and there must be agreement that the addition of these loads will not overload
the structure.
In addition, the attachment of this hardware should be done in such a way as to avoid any
significant reduction in capacity of the member to which it is being connected.
The authors of this manual in no way assume any liability relative to any limitations on the
capacity of the structure to resist the potential forces carried through the restraints or any
reduction in capacity of the structure that might result from improper or inappropriate
installation of the hardware.
General Installation Issues
Caution should be exercised when using struts for restraint in lieu of cables. A more
detailed summary is available earlier in this chapter. The use of struts will more than
likely require an increase in the hanger rod size and a decrease in the restraint spacing as
compared to cables, and appropriate factors must be used for component selection and
placement.
Code requirements also dictate that systems are supported from and restrained to
components that do not move in a significantly different fashion during an earthquake.
Because structures tend to flex about 1% with respect to height, this would indicate that a
relative motion between the floor and ceiling of a 10 ft tall room would be about ½”. As a
result, attachment of a component to the ceiling and restraint to the floor (or the reverse)
is unacceptable. Ideally, the components should be supported from and restrained to the
same surface (mount to ceiling/restrain to ceiling). As a worst case, no more than ¼”
relative motion should be permitted (which might permit mounting to the ceiling and
restraining to a surface near the top of an adjacent structural wall). The stiffer the
structure, the more flexibility the installer has in placing restraints.
STRUCTURAL ATTACHMENT DETAILS FOR DUCT RESTRAINTS


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When installing restraints there are often opportunities to use the same attachment points
used for suspending hanger rods to also connect restraint cables or struts. All hardware
size information indicated in this manual is based on independent support and restraint
hardware. The use of common connection points is not recommended and, if used, both
seismic and support forces along with worst-case safety factors and hardware selection
criteria must be included in the evaluation. This is beyond the scope of this document.
Connections to Masonry Structures (Including Concrete)
Masonry structural elements can be either concrete or block. When concrete, they might

be poured in place with a removable form, poured over decking, or pre-cast and erected
on site. When attaching to masonry, it is important to be aware of the locations of any
reinforcing steel that may be embedded in it. It is not permissible to damage the
reinforcement.
Damage to the reinforcement will (at best) weaken the structure and can (at worst) result
in severe injury or death. Do not under any circumstances drill into a masonry element
without first obtaining approval and, second, locating and avoiding any reinforcement
components.
All connections that bear the weight (only) of ceiling-mounted components must be rated
for a 5:1 safety factor, but may not require seismically approved anchorage hardware.
Any connection that must resist only a seismic force must use seismically rated hardware
with an inherent 2:1 safety factor. Connections that must withstand both seismic and
gravity loads require both seismically rated anchorage and a 5:1 safety factor. Examples
of the above are as follows:
Seismic
5:1 Rating
Hanger rod Anchorage for Cable-Restrained System Yes No
Restraint Anchor (Strut or Cable System) No Yes
Hanger rod Anchorage for Strut-Restrained System Yes Yes
Connections into portions of beams or other elements that are loaded in tension will have
a reduced capacity as compared to published ratings. These should be avoided, or if
unavoidable, should be analyzed independently of the charts and tables published in this
document.
All tables used in this document are based on the use of Kinetics Noise Control-supplied
seismically rated anchors. Caution should be used to ensure that adequate embedment
depth and cover (per local code or anchor manufacturer with a 1” minimum) is provided.


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Minimum Anchor Installation Requirements
Ceiling Connections

The most efficient connection to the underside of a concrete slab is with a single anchor.
Depending on the load requirements and available slab thickness, this may not be
practical, and in order to get adequate capacity, multiple anchors may be required.
Single anchor attachments can be made with anchors from ¼” up to ½” using the Kinetics
Noise Control KSCA bracket and the KSUA bracket as shown below.
KSCA Clip with Single ¼” to ½” Anchor
KSCA Clips for ¼” Through ½” Anchors


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For larger, single-anchor arrangements, the CCA can be used. Depending on the
orientation, it can be used with either a 5/8 or 3/4 anchor.

CCA Clips for Single 5/8 and 3/4 Anchors
Anchors can be embedded in concrete through the decking as shown below:
Typical Restraint Clip Anchored to Concrete Through Decking
In cases where multiple anchors are required to meet load and/or maximum allowable
embedment requirements, a clip fitted with a multiple-anchor embedment plate or a
bridging strut member should be used. If using a strut, spacing between anchors must
not be less than the allowed spacing per Kinetics Noise Control anchor data tables
(Chapter P10).
CCA Clip attached using Kinetics Noise Control 2/4 Bolt Mount Plate


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Multiple-Anchor Mounting Using Strut Channel
Under extreme conditions, where the slab to which the restraint is being attached is too
thin to achieve the needed capacity with conventional concrete anchors, it may be
necessary to bolt through the slab. This method eliminates concerns related to failures
due to anchor pullout and allows both the use of the higher through-bolt rating as well as
eliminates the penalty factors associated with connections using concrete anchors.
Connections made in this manner must bridge over reinforcement steel embedded in the
concrete slab as shown below.
Typical Through-Bolted Restraint Attachment Option
Wall and Column Connections
In general, restraint connections to walls and columns made of concrete are very similar
to the connections to the ceiling. Wall connections in this group, however, also
encompass connections to masonry walls which require some additional attention.
Illustrated below are the wall or column versions of the connections previously shown for
the ceiling applications.


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KSCA Clip with Single 1/4 to 1/2 Anchor
KSCU Clips for 1/4 Through 1/2 Anchors


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CCA Clip attached using Multiple Bolt Mount Plate and Strut Channel
Through-Bolted Connection
Because of the material’s lesser strengths, there are limited methods of attachment to
masonry block walls. Caution should be exercised to avoid installing wedge-type anchors
directly into the mortar used to cement the blocks together.
When used, anchors must penetrate into the core of the masonry unit and achieve
adequate embedment into the concrete or grout that fills the cavity. If the blocks are not
filled, the use of seismically rated wedge-type anchors should be avoided.
When working with hollow core block walls, restraint components must bolt through either
one or both surfaces of the block units. Penetrations through both sides require backer
plates of adequate size to distribute stress, while penetrations through one wall are more
limited in capacity and must make use of an umbrella or other positive gripping internal
element.
Masonry walls used to anchor restraints, as with other structural elements to which
restraints are connected, must be reviewed and approved by the design professional of
record on the project.


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Shown below is an example of a rated anchor embedded into the filled core of a masonry
wall unit.

Attachment to filled Masonry Wall with Wedge-Type Anchor
Through-Bolted Connection to a Hollow Block Masonry Wall


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Filled Umbrella-Type Anchor for ¼” and ½” Bolt Sizes
Connections to Steel Structures
Connections can be made to steel building elements by drilling and bolting, clamping (in
some instances), or by welding. As most connections are made to hanging components,
the most common structural members used as restraint supports tend to be beams and
trusses.
Some cautions are appropriate when connecting to these elements as their primary
function is normally to support the floor or roof above, and they are already subject to
significant stress. In addition, these elements are oriented such that, while they can
withstand high vertical loads, they can be quite weak when horizontal loads are applied to
them, especially when the loads are applied at 90 degrees to the beam axis (transverse).
While it is generally safe to make seismic restraint connections near the top of these
beams, it is often less convenient than making the attachment at the bottom. Extreme
caution must be exercised when connecting to the bottom flange of I-beams and, in
particular, open web joists, as frequently a small lateral load applied to these areas can
result in a catastrophic failure of the beam. No connections should be made without prior
review and approval of the design professional of record.
Assuming approval has been granted for the installation of a restraint at a particular
location, welding or clamping the restraint in place is typically the fastest, least invasive
method of making the connection. Bolting requires that the structural element be drilled
and is normally avoided where possible.


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Welded Connections to Beams and Columns
There are two basic methods for making weld attachments. The first is to directly weld a
bracket to the structure and the second is to weld a threaded piece of hardware (typically
a nut or bolt) to the structure and then attach the bracket to it. Looking first at the direct
bracket welding options, the most suitable clips are the KSCA and the CCA.
Below are shown optional weld locations for the KSCA clip mounted to both beams and
columns. These same arrangements are appropriate for floor- or roof-mounted
connections with the exception that they are inverted.

Weld Data and Orientation for the attachment of the KSCA Clip
The CCA clip can be mounted in a similar fashion.
Weld Data and Orientation for the attachment of the CCA Clip


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The second type of weld attachment is to weld hardware to the structure and use that to
attach the restraint bracket. The KSCU is well adapted to that type of connection.

Weld Data and Orientations for attachment of the KSCU Clip
Bolted Connections to Steel Members
When used, bolted connections to steel structural members are normally made to open
web joists or trusses. These are amenable to bolted connections as they have an integral
slot, although caution is required to ensure that the addition of the restraint loads will not
result in a buckling failure. It is also important to ensure that the load is oriented in such a
way as to not cause the attachment bolt to slip in the slot to which it is attached.
Transverse load Connections to “X” Braced Open Web Trusses
It is not recommended that restraints be connected to the bottom flange of an open web
truss without substantial “X” bracing in the immediate area of the restraint attachment
point. The bracing must be sufficient in nature and adequately connected to the truss to


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carry all restraint loads to the deck above.

Connections to the Top Chord of an Open Web Truss
“X” bracing is normally not required when restraints are connected to the top chord of an
open web truss as long as the truss is adequately tied into the decking and/or floor
structure above. This, along with the case below showing loads that are carried parallel to
the truss, transfer only minimal stress to the truss itself. Even so, as with the other
arrangements, permission should be obtained before making either of these connections.
Bolted Connection to an Open Web Truss for loads parallel to the Truss


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Clamped Connections to Steel Members
Another frequent restraint connection arrangement is to clamp the cable to a beam with a
beam clamp. Again it is critical to ensure that the addition of these loads will not result in
damage to the beam. The beam clamp selected must have a significant lateral force
transferring capacity. Most readily available clamps are intended as supports for vertical
loads and have only minimal lateral capacity. As such they are not suitable.
Shown below is Kinetics Noise Control’s KSBC beam clamp.

The KSBC Beam Clamp can be mated with a wide range of I-Beams as well as
KSUA, KSCA, and CCA Restraint Clips
KSBC Beam Clamps are also compatible with Strut and Angle Bracing


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Connections to Wood
Connections to Ceilings and other Horizontal Surfaces
Wood structural members can often create issues when it comes to connecting seismic
restraint hardware. Although lag screws are easy to install, adequate depth, end and
edge distance issues frequently make them impractical. The option to bolt through a
wood member and include a backer plate eliminates the depth issue, but the end and
edge distance requirements still must be met. The minimum edge distance is 1.5 bolt
diameters and the minimum end distance is seven times the bolt diameter.

The capacity of connections to wood using through bolts and a backer plate is limited only
by bolt capacity and the structural capacity of the frame member. Capacities using lag
bolts are severely limited, as the pull-out capacity of the lag bolt is much less than that of
a through bolt.
Shown below are typical connections to the underside of horizontal surfaces (floor-
mounted systems would be the same, but inverted).
KSCA Clip with Single 1/4 to 1/2 Lag Bolt
KSCU Clips for 1/4 Through 1/2 Lag Bolts


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CCA Clip with Lag Bolts 5/8 and 3/4 Diameter

Where loads are such that a single anchor is inadequate, multiple anchors can be used as
shown below.
As long as adequate resistance to prevent twisting of the joists is provided, it is possible to

bridge across multiple joists and install a restraint in between.
Two-Anchor Mounting using a Strut Channel


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For worst-case conditions, as with concrete anchors, it is possible to bolt through a wood
member with a backer plate.

Through-Bolted Application with Backer Plate
As with concrete anchors, the wall and column connections to wood members are very
similar to those for horizontally oriented surfaces. Shown below are typical examples.
KSCA Clips Mounted with Single ¼” to ½” Lag Bolts
KSCU Clips for ¼” and ½” Diameter Lag Screws


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CCA Clip with Lag Bolts 5/8” and 3/4" Diameter
Multiple Bolt Anchor Plate with CCA Clip


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Conclusion
This sections attempts to list the bulk of the structural attachment arrangements that are
likely to be found in the field. Not all combinations of struts, angles, cables, etc., have
been shown for each option. Except for cases where a connection obviously won’t fit, the
ability to “mix and match” the various end connection combinations shown can be
assumed.


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NON-MOMENT GENERATING CONNECTIONS
The IBC and 97 UBC codes allow the omission of seismic restraints for most piping,
conduit and ductwork runs without regard to size but that are located within 12” of the
structure. This figure is 6” for fire sprinkler piping. In order to qualify for this, the following
parameters must be met:
1) The length of all supports on the run measuring from the top anchorage point to the
connection point to the trapeze bar or the top of a singly supported pipe or conduit run
must not exceed 12” (6” for fire piping).
2) Unrestrained free travel of the supported system must be such that over the course of

its movement, contact is not made with any other system, component or structural
element that can result in damage to either the supported system or the object it hit.
3) The top connection to the structure must include a Non-Moment generating connection
to prevent damage to the hanger rod or support strap.
A Non-Moment generating connection is any device that would allow a free flexing action
of the hanger rod or support strap for an unlimited number of cycles without its being
weakened. This motion must be permitted in any direction.
Shown below are typical examples of acceptable Non-Moment generating connections.

Any other device that allows the same freedom of motion is equally acceptable.
A hanger rod rigidly embedded into the underside of a concrete structural slab is not.
SHEET
METAL
ISOLATOR STRAP
CLEARANCE
CHAIN


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Connection Options for Awkward Situations
Almost every project will include some areas where installing restraints in a conventional
fashion will be difficult. This segment of the manual offers options to consider when
confronted with various situations.
Long, Narrow Hallways
Probably the most common issue in the field is how to deal with lateral restraints in long,
narrow hallways. Normally there is considerable congestion in these areas and not
enough room to angle restraints up to the ceiling structure. Often the walls are not

structural and do not offer a surface to which to anchor.
When evaluating halls, the first issue is to determine if either of the walls of the hall is
structural. If either wall is structural, it offers a surface to which the restraints can often be
attached. For structural walls, any relative displacement issues between the wall and the
structure supporting the pipe must be identified. The maximum permitted relative
displacement is ¼ inch, which for most structures corresponds to a difference in elevation
of approximately 2 feet (see also the structural attachment section of this chapter).
Assuming the wall meets both of the above requirements, a lateral restraint can be run
either directly over to the wall or up at a slight angle to the wall. Normally this would be
done with a strut as shown below.
Trapeze-Mounted Duct Restrained to Structural Wall

or Column with a Horizontal Strut
CONNECTION OPTIONS FOR AWKWARD SITUATIONS


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Trapeze-Supported Duct Restrained to Structural
Wall or Column with an Sloping Strut
Clevis-Supported Ductwork Restrained to Structural Wall or Column
For the case where there are no nearby structural connection points or where the nearby
structural elements are not suitable, there are several options that can be considered.
The first option is to restrain to the ceiling using “X” bracing or a diagonal strut.
“X” or Diagonally Braced Restraint Arrangement


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A “K” or double “K” brace can also be used. The “K” can either be located inside the
support rods or outside the support rods, but in the case of a double “K”, both sides must
be identical (either inside or outside).

Single and Double “K” Brace Restraint Arrangement
In cases where only non-structural walls limit access for restraint, it is frequently possible
to penetrate the non-structural wall and shift the lateral restraint device to the opposite
side of the wall or partition as shown here.
Wall Penetration Restraint (Cable)
Wall Penetration Restraint (Strut)


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Axial Restraint Strut at a Dogleg
This arrangement is often a convenient way to connect an axial restraint and can occur
both in the horizontal and vertical plane. Often it will be found that when installing
ductwork, a jog has been added to a run to avoid running into a column or other structural
member. Where this occurs, it offers an easy way to connect an axial restraint.

Piggyback or Double-Tier Restraint
In congested areas, occasionally there is a double layer of ductwork supported off a single
trapeze arrangement. It is possible under some conditions to brace one trapeze bar to
the other, and then restrain the second trapeze bar to the structure. If doing this, there
are a couple of cautions. First, the restraint capacity for the second trapeze bar must be
adequate to restrain the total load from both bars and, second, the ductwork must be
similar in nature and ductility.
Piggyback or Double-Tier Restraint Arrangement


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Restraints for Ductwork Mounted Well Below the Support Structure
This situation is not easily handled. Past history has shown, and the code is quite clear,
that it is not a good idea to support the duct from one structural element and restrain it
using another structural element that will undergo significantly different motions.
Restraints fit in this fashion will likely fail or cause the duct supports to fail. Neither of
these outcomes is desirable.
About the only solution to this is to add a support structure for the ductwork that is located
either just above or just below the level of the duct. The ductwork can then be both
attached and restrained to this structure.

The structure can be supported off the floor, off the ceiling, or from structural walls or
columns. The support structure must be rigid enough to absorb all of the seismic loads,
and particularly the moments, with minimal deformation, transferring pure shear or tensile
forces into the supports.


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TABLE OF CONTENTS
ELECTRICAL DISTRIBUTION SYSTEMS Chapter D9
Seismic Forces Acting On Cable Trays & Conduit D9.1
Basic Primer for the restraint of Cable Trays & Conduit D9.2

Pros and Cons of Struts versus Cables D9.3
Layout Requirements for Conduit/Tray Restraint Systems
Requirements for Conduit/Tray Restraints D9.4.1

(Definitions and Locating Requirements)
Ceiling Supported Conduit/Tray Restraint Arrangements D9.4.2
Floor Supported Conduit/Tray Restraint Arrangements D9.4.3
Conduit/Tray Restraint System Attachment Details
Transferring Forces D9.5.1
Cable Clamp Details D9.5.2
Conduit/Tray Attachment Details D9.5.3
Structure Attachment Details D9.5.4
Non-Moment Generating Connections D9.5.5
Connection Options for Awkward Situations D9.6
TABLE OF CONTENTS (Chapter D9)

SUSPENDED ELECTRIC CABLE TRAYS AND CONDUIT RELEASE DATE: 10/12/04
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Seismic Forces Acting on Electrical Distribution Systems
When subjected to an earthquake, electrical distribution systems must resist lateral and
axial buckling forces, and the restraint components for these systems must resist pullout
and localized structural failures.
Most electrical distribution systems are suspended from the deck above on fixed hanger
rod systems. They may be supported singly or there may be several pieces of conduit or
buss ducts attached to a common trapeze. On some occasions the conduit may run
vertically or may be mounted to the floor.

Suspended Systems
Most codes do not require that electrical distribution supported on non-moment generating
(swiveling) hanger rods 12 in or less in length be restrained. The 12 in length was
determined based on the natural frequency of systems supported on the short hanger
rods. In practice, it has been found that the vibrations generated by earthquakes do not
excite these types of systems and, although the systems move back and forth somewhat
as a result of an earthquake, they do not tend to oscillate severely and tear themselves
apart.
There are also exclusions in most codes for small pieces of conduit, no matter what the
hanger rod length. Again, the basis for this exclusion is based on the post-earthquake
review of many installations. It has been found that smaller conduit runs are light and
flexible enough that they cannot generate enough energy to do significant damage to
themselves.
For cases where restraints are required, however, the forces involved can be significant.
This is due to the difference between the spacing of the system supports and their
restraints. Supports for these systems are typically sized to carry approximately a 10 ft
length of conduit or duct (in the case of trapezes, multiple pieces of conduit each approx
10 ft long). Seismic restraints, on the other hand, are normally spaced considerably
further apart with the spacing varying by restraint type, restraint capacity, conduit size,
and the seismic design load. It is very important to be aware of the impact of the
difference in spacing as the wider this spacing, the larger the seismic load when
compared to the support load. Guidance in determining restraint spacing requirements is
available in Chapter D4 of this manual. (Note when using these tables that conduit should
be assumed to be similar in weight and performance to the equivalent pipe size.)
To illustrate this difference, consider a simple example of a single piece of conduit

weighing 50 lb/ft being restrained against a 0.2g seismic force with restraints located on
80 ft centers and supports located on 10 ft centers. The load that is applied to the hanger
rods by the weight of the conduit is 50 lb/ft x 10 ft or 500 lb each (assuming single rod
supports). The horizontal load that occurs at the restraint locations is the total restrained
SEISMIC FORCES ACTING ON ELECTRICAL DISTRIBUTION SYSTEMS


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weight (50 lb/ft x 80 ft = 4000 lb) multiplied by the seismic force (0.2g) or 800 lb. Thus the
seismic load is larger than the vertical dead load.
Restraints for suspended systems are normally in the form of cables or struts that run
from the conduit up to the deck at an angle. Because of the angle, horizontal seismic
loads also generate vertical forces that must be resisted. Therefore, restraint devices
must be attached at support locations so that there is a vertical force-resisting member
available.
As the angle becomes steeper (the restraint member becomes more vertical), the vertical
forces increase. At 45 degrees the vertical force equals the horizontal force and at
60 degrees the vertical force is 1.73 times the horizontal force.

The net result is that for cable systems or for struts loaded in tension, the uplift force at
the bottom end of the restraint can be considerably higher than the downward weight load
of the conduit. Returning to our example, assume that we have a restraint member
installed at a 60 degree angle from horizontal and that the lateral force will load it in
tension. In this case, the 800 lb seismic force generates an uplift force of 1.73 x 800 lb or
1384 lb. This is 884 lb more than the support load and, depending upon the support rod
length and stiffness, can cause the support rod to buckle. Rod stiffeners are used to
protect against this condition and sizing information is available in Chapter D4 of this
manual.
Unlike cables, if struts are used for restraint they can also be loaded in compression. In
the example above, if the strut were loaded in compression, the 1384 lb load would be
added to the support load (trying to pry the hanger rod out of the deck). The total support
capacity required would be 1384 lb + 500 lb or 1884 lb. As a consequence, when using
struts, the hanger rod must be designed to support 1884 lb instead of the 500 lb maximum
generated with cables. Hanger rod sizing information is also available in Chapter D4 of
this manual.
Riser Systems
Where conduit is running vertically in structures, except for the loads directly applied by
vertical seismic load components identified in the code, there will be little variation in
vertical forces from the static condition. Lateral loads are normally addressed by local
anchorage and the spacing between these anchors is not to exceed the maximum
tabulated lateral restraint spacing indicated in the design tables in Chapter D4.
Floor-Mounted Systems
The primary difference between floor- and ceiling-mounted electrical distribution systems
is that the support loads in the distribution system support structure are in compression
instead of tension (as in the hanger rods). Although a support column and diagonal


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cables can be used, a fixed stand made of angle or strut is generally preferred. Rules
relating to restraint spacing and the sizing information for diagonal struts are the same as
for hanging applications.
However, the support legs need to be designed to support the combined weight and
vertical seismic load (for a two-legged stand and the example above, 500 lb / 2 + 1384 lb
or 1634 lb) in compression (Note: 500 lb / 2 is the load per leg for two legs). The
anchorage for the legs needs to be able to withstand the difference between the dead
weight and the vertical seismic load (in the example above 1384 lb - 500 lb / 2 or 1134 lb).


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Basic Primer for Suspended Electrical Distribution Systems
Failures in electrical distribution systems resulting from earthquakes have historically

resulted in loss of building services, are possible fire sources and carry with them the risk
of occupant electrocution. While to date, the recorded instances of dollar damage to the
building and its contents has been less than that of pipe or duct systems, the risk exists
for serious damage and possible loss of life. In addition, failure of the building’s
mechanical systems can render the structure unoccupiable until the damage is corrected,
and result in major problems for the tenants and/or owners.
As with the piping and duct systems, requirements for the restraint of electrical distribution

systems have also become much more stringent.
Within a building structure, there are multitudes of different kinds of electrical systems,
each with its own function and requirements. These include building power,
communication, system monitoring, HVAC control to name a few. Requirements for the
systems vary based on the criticality of the system and those systems with which it
interacts. Code mandated requirements for the restraint of electrical distribution systems
are addressed in Chapter D2 of this manual (Seismic Building Code Review).
Prior to applying this section of the manual, it is assumed that the reader has
reviewed Chapter D2 and has determined that there is indeed a requirement for the
restraint of the system. This chapter of the manual is a “how to” guide and will deal
only with the proper installation and orientation of restraints and not whether or not
they are required by code or by specification.
This chapter also does not address the sizing of restraint hardware. Chapter D4
includes sections on sizing componentry based on the design seismic force and
the weight of the system being restrained.
Process electronics that are not directly associated with building operating systems may
have their own set of requirements that should be addressed separately. High voltage
electrical systems, whether building or process related should be restrained per code
requirements. If there are no applicable special requirements, all systems should be
restrained in a similar fashion to the building mechanical systems. This manual will not
address any special requirements.
Building electrical systems must be restrained per code. Refer to the code review chapter
(D2) of the manual for applicable design requirements.
In many cases, conduit can be excluded from restraint if it is small enough in size or
mounted in close proximity to the ceiling structure. When applying this exemption, current
codes require the installation of a “non-moment generating connection” at the top
anchorage point. This term is often confusing and deserves further clarification. A “non-
BASIC PRIMER FOR SUSPENDED ELEC DISTRIBUTION SYSTEMS


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moment generating connection” is one that will allow the supported pipe to swing freely in
any direction if acted on by an outside force. Some examples of “non-moment
generating connections” are illustrated below.
BASIC PRIMER FOR SUSPENDED ELEC DISTRIBUTION SYSTEMS


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Pros and Cons of Struts Versus Cables
Both cables and struts have their place in the restraint of conduit and other electrical
distributions systems. In order to minimize costs and speed up installation, the
differences between the two should be understood.
In general, distribution systems restrained by struts will require only 1 brace per restraint
location while systems restrained with cables requires that 2 cables be fitted forming an
“X” or a “V”. As a trade-off, the number of restraint points needed on a given run of
conduit or distribution ducts will typically be considerably higher for a strut-restrained
system than for the cable-restrained system and, generally, strut-restrained systems will

be more costly to install.
An added factor to consider when selecting a restraint system is that once a decision is
reached on the type to use for a particular run, code requirements state that the same
type of system must be used for the entire run (all cable or all strut). Later sections in this
chapter will define runs, but for our purposes at present, it can be considered to be a more
or less straight section of piping.
The obvious advantage to struts is that, when space is at a premium, cables angling up to
the ceiling on each side of a run may take more space than is available. Struts can be
fitted to one side only, allowing a more narrow packaging arrangement.
The advantages of cables, where they can be used, are numerous. First, they can usually
be spaced less frequently along a distribution run than can struts. Second, they cannot
increase the tensile forces in the hanger rod that results from the weight load, so rod and
rod anchorage capacities are not impacted. And third, they are easily set to the proper
length.
To better explain the differences between the systems, it is necessary to look at how
seismic forces are resisted with cables and struts. Shown below are sketches of both a
cable-restrained and strut-restrained piece of conduit.
Cable Restrained
PROS AND CONS OF STRUTS VERSUS CABLES


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Strut Restrained
The key factor to note is that cables can only be loaded in tension. This means that

seismic forces can only generate compressive loads in the hanger rod. Seismic forces
can, however, load the strut in compression resulting in a tensile load on the hanger rod.
This tensile load is in addition to any deadweight load that may already be supported by
the hanger and is often significantly higher than the original load. This has the potential to
rip the hanger rod out of the support structure and must be considered when sizing
components.
Because of this added tensile component and the resulting impact on the necessary
hanger rod size, most strut manufacturers limit the maximum allowable strut angle (to the
horizontal) to 45 degrees. This is lower than typical allowable angles for cables that often
reach 60 degrees from the horizontal. Although the tables listed in Chapter D4 of this
manual allow the use of higher angles for strut systems, users will find that the penalties
in hanger rod size and anchorage will likely make these higher angles unusable in
practice. To put this into context, examples will be provided at both 45 degrees and
60 degrees from the vertical to indicate the impact on capacity that results from the angle.
For a 45 degree restraint angle, if we assume a trapeze installation with the weight (W)
equally split between 2 supports, the initial tension in each support is 0.5W. Using a
0.25g lateral design force (low seismic area), the total tensile load in a hanger increases
to 0.75W for bracing on every support and 1.0W for bracing on every other support, if a
strut is used.
For reference, if struts are used in a 60 degree angle configuration (from the horizontal),
the tensile force in the hanger rod for all cases increases by a factor of 1.73 (tan 60) over
that listed in the previous paragraph. This means that the tensile force becomes .94W for
bracing on every support and 1.36W for bracing on every other support.
On the other hand, where 0.25g is applicable, buckling concerns in conduit are such that
the spacing between lateral restraints can be as high as 40 ft and for axial restraints, 80 ft.
If we were to try to use struts placed at a 40 ft spacing in conjunction with supports
spaced at 10 ft, the tensile force developed by a seismic event in the rod increases to


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1.5W for 45 degree configurations and to 2.23W for 60 degree configurations.
As mentioned earlier, there is no increase in the rod forces for cable restrained systems.
Using real numbers based on a 40 ft restraint spacing and a 60 degree angle

configuration, if the peak tensile load in the hanger rod is 500 lb for a cable restrained
system, it becomes 2230 lb for an otherwise identical strut restrained system.
A summary of the above data, based on a 500 lb weight per hanger rod (1000 lb per
trapeze bar) and including concrete anchorage sizes and minimum embedment is shown
below.

Summary of Hanger Rod Tensile Loads based on 500 lb per Rod Weight
Tens Force (lb) Min Rod (in) Min Anc (in) Embed (in)
Every Hanger Braced (10')
Cable Angle = 45 500 0.38 0.38 3.00
Strut Angle = 45 750 0.38 0.38 3.00
Cable Angle = 60 500 0.38 0.38 3.00
Strut Angle = 60 933 0.50 0.50 4.00
Every other Hanger Braced (20')
Cable Angle = 45 500 0.38 0.38 3.00
Strut Angle = 45 1000 0.50 0.50 4.00
Cable Angle = 60 500 0.38 0.38 3.00
Strut Angle = 60 1365 0.50 0.63 5.00
Every fourth Hanger Braced (40')
Cable Angle = 45 500 0.38 0.38 3.00
Strut Angle = 45 1500 0.63 0.63 5.00
Cable Angle = 60 500 0.38 0.38 3.00
Strut Angle = 60 2230 0.63 0.75 6.00
Max Spacing between Braces (80')
Cable Angle = 45 500 0.38 0.38 3.00
Strut Angle = 45 2500 0.75 0.75 6.00
Cable Angle = 60 500 0.38 0.38 3.00
Strut Angle = 60 3960 0.88 1.00 8.00
Note: The above anchorage rating is based on ICBO allowables only. Often the
underside of a concrete floor slab is in tension and if this is the case, the anchorage
capacity may need to be further de-rated (forcing the need for an even larger hanger rod
than is indicated here).
The net result is that the ability to use struts is highly dependent on the hanger rods that
are in place. If these were sized simply on deadweight, the added seismic load, even in
relatively low seismic areas, can quickly overload them. The only recourse is to either
replace the hanger rods with larger ones or decrease the restraint spacing to the point at


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which virtually every support rod is braced.
It should also be noted that the hanger rods in tension become seismic elements. This
occurs with struts, but does not with cables. As a result, the system must comply with all
of the anchor requirements specified by ICBO. This includes the use of wedge-type
anchors and embedment depths that are a minimum of 8 anchor diameters. With larger
anchor sizes, floor slab thickness may cause this to become a significant problem.
With both cables and struts, the hanger rods can be loaded in compression. As the
seismic force increases, it eventually overcomes the force of gravity and produces a
buckling load in the hanger rod. It is mandatory in all cases that the rod be able to resist

this force.
There is a wide range of variables involved in determining the need for rod stiffeners to
resist this buckling load. Factors that impact this need are 1) the magnitude of the
compressive force, 2) the weight load carried by the hanger rod, 3) the length of the
hanger rod, 4) the diameter of the hanger rod, and 5) the angle between the restraint strut
or cable and the horizontal axis.
Tables are included in Chapter D4 of this manual that allow the user to determine if there
is a need for a stiffener and to allow the proper selection if required.
In rare instances, electrical distribution systems are isolated. In these cases and because
uplift occurs, some attention must be given to the isolator itself. First, when using
isolators, the location of the isolation element needs to be at the top end of the hanger rod
(close to, but not tight against the ceiling). If placed at the middle of the hanger rod, the
rod/isolator combination will have virtually no resistance to bending and will quickly buckle
under an uplift load.
Second, a limit stop must be fit to the hanger rod, just beneath the hanger such that when
the rod is pushed upward a rigid connection is made between the hanger housing and the
hanger rod that prevents upward motion. This is accomplished by adding a washer and
nut to the hanger rod just below the isolator (see the sketch below).


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Requirements for Distribution System Restraints
Definitions and Locating Requirements
SMACNA has developed a set of restraint placement criteria based on analytical review,
practical experience, and historical analysis. The criteria presented in this manual is
generally based on the SMACNA criteria, with the only exceptions being an extrapolation
of the data to higher seismic force levels and an increase in allowable spacing where
restraint hardware capacity (as illustrated in the SMACNA guide) would be exceeded.
With respect to the conceptual restraint arrangement illustrations, the SMACNA concepts
are appropriate and are referenced here.

In general, conduit and bus ducts are restrained in lengths called “runs.” Therefore before
getting into a detailed review of the restraint systems it is imperative that a definition of
“run” as well as other key terms be addressed.
Definitions
Axial In the direction of the axis of the run.
Lateral Side to side when looking along the axis of the run.
Pipe or Conduit Clamp A heavy duty split ring clamp tightened against the conduit to
the point that it can be used to control the axial motion of the conduit, tray or duct.
Restraint Any device that limits the motion of a conduit or duct in either the lateral or
axial direction.
Run A more or less straight length of conduit or duct where offsets are limited to not
more than S/16 where S is the maximum permitted lateral restraint spacing (a function of
conduit or duct size and seismic forces) and the total length is greater than S/2. (Note: S
dimensions for various conditions are listed in Chapter D4.)


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Short Run A run as defined above where the total length is less than S/2 and where it is
connected on both ends to other runs or short runs.
Drop A length of conduit that normally extends down from an overhead distribution
system and connects to a piece of equipment, usually through some type of flex
connector. The drop can also extend horizontally. In order to qualify as a drop, the length
of this conduit must be less than S/2. If over S/2, the length of conduit would be classified
as a run.

Restraint Requirements
1) Full runs greater in length than S/2) must be restrained in both the axial and lateral
direction. If the run is not a short run or a drop, it must, as a minimum, be laterally
restrained at the last support location on each end.


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2) If a run is longer than “S”, intermediate restraints are required to limit the spacing to
that permitted by the building code (see table in Chapter D4).

3) Axial restraints attached to the run of conduit along its length must be connected using
a conduit clamp (as previously defined).
4) Short runs or drops need only have one lateral and one axial restraint.
5) If a lateral restraint is located within 2 feet of a corner (based on a measurement to the

conduit or duct centerline), it can be used as an axial restraint on the intersecting run.


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6) Larger trays or conduit cannot be restrained with restraints located on smaller branch
runs.

7) Within a run, the type of restraint used must be consistent. For example, mixing a
strut with cable restraints is not permitted.


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8) With longer hanger rods, rod stiffeners are likely to be required. Refer to the
appropriate table in Chapter D4 to determine: (1) if needed, (2) what size stiffener
material is appropriate, and (3) how frequently it needs to be clamped to the hanger
rod.

9) In addition to possibly requiring rod stiffeners, when struts are used to restrain conduit,
the size of the hanger rod and its anchorage also become critical. Again refer to the
appropriate table in Chapter D4 to determine the minimum allowable size for the
hanger rod and anchor.


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10) In some cases, it may be possible to locate the electrical distribution system close
enough to the support structure (12”) to eliminate the need for restraint. (Refer to the
building code review chapter (D2) to determine if this exemption is applicable.) If it is
applicable, the 12” dimension is measured as shown below.

11) When using the above rule it is critical that all support locations in a run conform. If
even one location exceeds 12”, the run cannot be exempted from restraint.


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Ceiling-Supported Electrical Distribution System Restraint
Arrangements
It is assumed in this section that all conduit is rigid. For non-rigid conduit and if the

conduit is large enough to require restraint, adequate hardware to accomplish this task is
required at each support location.

on the same job.
the same run.
CEILING-SUPPORTED ELEC DIST SYSTEM RESTRAINT ARRANGEMENTS


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( 10 degrees) to the run in plan. Axial restraints should be in line with the run,
10 degrees, again in the plan view. All restraint cables should be aligned with each

In general, when restraining electrical distribution systems and conduit the component
actually being restrained is the system support device. This may be a clevis, a clamp, or
a trapeze bar. Because the goal is to restrain the actual cable tray, duct or piece of
conduit, it is necessary that the restrained element be connected in such a way as to
transfer the appropriate forces between the two. For example, if an axial restraint is
installed on a trapeze bar which in turn supports a piece of conduit that is not clamped in
place, it is obvious that the axial forces generated by the conduit cannot be restrained by
the connection to the trapeze bar. Some other arrangement is needed.
When firmly connecting restraints to cable trays, ducts or conduit there are a few general
rules that should be followed:
1) A conventional pipe or conduit clevis cannot restrain a piece of conduit in the axial
direction.
2) Trapeze-mounted ducts, trays and conduit should be tightly connected to the trapeze
bar.
3) If a tray or duct is used and it is mounted with the long dimension in the horizontal
plane, the maximum spacing for restraints should be based on the allowable spacing
for a pipe of a diameter equal to the tray’s long axis dimension.
4) If a tray or duct is used and it is mounted with the short dimension in the horizontal
plane, the maximum spacing for restraints should be based on the allowable spacing
for a pipe of a diameter equal to the tray’s short axis dimension.
In addition, when sizing restraint components for multiple pieces of conduit, the total
weight of all the restrained conduit must be considered.


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Hanging Systems Restrained with Cables
Hanging systems may include supports for single or multiple conduit runs, buss ducts or
cable trays. Single conduit runs can be supported using clevis hangers but wherever
multiple items are used, they are normally supported on trapeze bars.
For a cable-restrained conduit supported by a hanger clevis, there are two options for
non-isolated installations. Since the isolation of conduit is rare, it will not be addressed
here, but would be similar to the isolated arrangements for piping and ductwork shown in

the previous two chapters. These non-isolated options are shown below.
Lateral Cable Restraints clamped to Hanger Rod and attached to Clevis Tie Bolt
There are many options that exist for the arrangements of lateral restraints used in conjunction
with trapeze-mounted systems. Shown below are several options for cable-restrained systems.
Lateral Cable Restraints Mounted to a Trapeze


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Axial restraints cannot be connected to a standard clevis and be expected to work. This
is because there is inadequate friction between the bracket and the conduit to transfer the
forces in the conduit to the restraint. When axially restraining conduit, a trapeze or
conduit clamp tightly attached to the conduit is the most common connecting device used.
Details on these connections will be addressed in later sections.

Note: Axial restraints offset from the restrained run of conduit, duct or cable tray will
generate additional bending forces in the restrained system. This is true whether
mounted to one end of a trapeze or along side a single duct or tray rather than directly
over its center. Provisions should be made to avoid offsetting axial restraints when
restraining a single conduit. This requires either that the restraint be attached to the
centerline of the conduit, that the axial restraint be combined with a lateral restraint to
form an “X” arrangement or that 2 axial restraints be fitted, one on either side of the
conduit (See also the Figure below). (Note that when specifying and providing restraints,
KNC assumes one of the 2 former arrangements are used, if the latter case is used, the
installation contractor will have to procure and additional restraint set from KNC.) For
trapezed systems supporting multiple components, a single axial restraint should be
located at the approximate center of the trapeze bar or pairs of axial restraints should be
installed on each end of the trapeze bar.
Various Acceptable Axial Restraint Arrangements
Hanging Systems Restrained with Struts
As with cable restraints, hanging systems may include supports for single pieces of
conduit, multiple conduit runs or a mixture of cable trays, ducts and conduit. Single
conduit arrangements can be supported using a clevis or conduit hanger, but multiple
components are normally supported on trapeze bars.


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Axial Cable Restraints
For a strut-restrained conduit supported by a hanger clevis there are two typical options.
One is to connect the restraint to the clevis bolt and the other is to connect the restraint to
the hanger rod. These are shown below.
Typical Lateral Restraint Strut Arrangements for Clevis-Supported Conduit
Shown below are 3 options for trapeze-supported conduit. All are equivalent.
As with cables, axial restraints using struts cannot be connected to a standard clevis and
be expected to work. When axially restraining conduit, a trapeze or conduit clamp tightly
attached to the conduit is the most common connecting device. It may however be

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possible to attach the restraint to a connector fitting in some cases.

3 Arrangements for Laterally Restrained Trapezes with Struts
As with the cable restraints, it must be recognized that axial restraints offset from the
restrained run will generate additional bending forces in the duct, tray or conduit itself.
This is true whether mounted to one end of a trapeze or along side a single piece of
conduit rather than directly on its center. Provisions should be made to avoid offsetting
axial restraints when restraining a single conduit. This requires either that the restraint be
attached to the centerline of the conduit, that the axial restraint be combined with a lateral
of the conduit. (Note that when specifying and providing restraints, KNC assumes one of
the 2 former arrangements are used, if the latter case is used, the installation contractor
will have to procure and additional restraint set from KNC.) For duct or tray installations,
the maximum offset (from the centerline) cannot exceed the width dimension of the tray or
duct. For trapezed systems supporting multiple components, a single axial restraint
should be located at the approximate center of the trapeze bar or pairs of axial restraints
should be installed on each end of the trapeze bar.
Conduit Axially Restrained with Struts


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Floor- or Roof-Supported Electrical System Restraints
systems, the actual arrangements of these systems can vary significantly. Despite what
different floor- and roof-mounted restraint arrangements, all of which can be used in
conjunction with the design “rules” provided in this manual.
sections of this manual. It is assumed in this manual that the restraint component is

This manual addresses diagonal bracing oriented between horizontal and 60 degrees

(±10 degrees) to the conduit or tray in the plan view. Axial restraints should be in line with
the conduit or tray (±10 degrees) again in the plan view. All restraint cables should be
aligned with each other. See the sketch below.
FLOOR- OR ROOF-SUPPORTED ELECTRICAL SYSTEM RESTRAINTS


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In general, when restraining conduit or trays, the component actually being restrained is
the support device for the system. For floor-mounted equipment this would normally be
either a fabricated frame or a trapeze bar. Because the goal is to restrain the actual
conduit or tray, it is necessary that the restrained element be connected to the conduit or
tray in such a way as to transfer the appropriate forces between the two. For example, if
an axial restraint is installed on a trapeze bar which in turn supports a conduit or tray that
is not clamped tightly to it, it is obvious that the axial forces generated by the conduit or
tray cannot be restrained by the connection to the trapeze bar and some other
arrangement is needed.
With respect to firmly connecting restraints to conduit or tray, there are a few general rules
that should be followed:

1) For Axial restraints, conduit clamps must be heavy duty and must be tightly clamped
against the conduit itself.
2) If the pipe is wrapped or covered with a material that can reduce the clamps ability to
grip it, the material must be removed or hardened to the point that positive clamping
action can be assured.
3) Trapeze-mounted conduit or trays should be tightly clamped or bolted to the trapeze
bar.
In addition, when sizing restraint components that affect multiple components, the total
weight of all of the restrained componentry must be considered.
Floor- or Roof-mounted Systems Restrained with Cables
Floor- or roof-mounted systems may include supports for single runs of conduit, multiple
runs, cable trays or bus ducts. Typically, simple box frames are fabricated to support
these, no matter what they are.
For a cable-restrained support brackets there are four options normally encountered for
non-isolated systems. As Electrical distribution systems are rarely isolated, for the
purposes of this document, isolated systems will not be addressed. These options are
shown below. The vertical legs of the support bracket must be sized to carry both the
weight load of the supported pipes as well as the vertical component of the seismic
forces. Refer to Chapter D4 for more detailed information as to how to size these
members.
When axially restraining conduit, a trapeze or clamp tightly fitted to the conduit is the most
common connecting device between the restraint strut and a single piece of conduit.

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When connecting to a cable tray or bus duct, bolts or tray clamps are typically used.
SINGLE LEG
OUTSIDE RESTRAINT RESTRAINT

X BRACED INSIDE RESTRAINT
Lateral Cable Restraints used in conjunction with floor-mounted distribution

system support stands
Note: Axial restraints offset from the restrained run will generate additional bending forces
in the restrained system. This is true whether mounted to one end of a trapeze or along
side a single piece of conduit rather than directly under its center. When the restraint is
offset, the maximum permissible offset from the center of the conduit, tray or duct is equal
to its diameter or width. For trapezed systems supporting multiple runs, a single axial
restraint should be located at the approximate center of the trapeze bar or pairs of axial
restraints should be installed on each end of the trapeze bar or support frame.
PIPE SUPPORT
Axial Cable Restraints


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Floor- or Roof-Mounted Systems Restrained with Struts
As with cable restraints, floor- or roof-mounted electrical distribution support systems will
normally involve a box frame that supports the system (single or multiple runs) with some
kind of a trapeze bar.
With struts there are three typical configurations as shown below.

SIDE STRUT DIAGONAL BRACE
ANCHOR TO
STRUCTURAL WALL
Typical Lateral Restraint Strut Arrangements for Conduit
When axially restraining conduit, a trapeze or clamp tightly fitted to the conduit is the most
common connecting device between the restraint strut and a single piece of conduit.
When connecting to a cable tray or bus duct, bolts or tray clamps are typically used.
As with the cable restraints, it must be recognized that axial restraints offset from the
restrained conduit, trays or ducts will generate additional bending forces in the
component. This is true whether mounted to one end of a trapeze or along side a single
piece of conduit rather than directly under its center. When the restraint is offset, the
maximum permissible offset from the center of the conduit, tray or duct is equal to its
diameter or width. For trapezed systems supporting multiple components, a single axial


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restraint should be located at the approximate center of the trapeze bar or pairs of axial
restraints should be installed on each end of the trapeze bar or support frame.
PIPE SUPPORT

Piping Axially Restrained with Struts

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D9.4.3

Transferring Forces (Electrical System Restraints)
conditions in any given installation, piping, duct, and electrical distribution systems are
particularly prone to problems in this area.
cable ends together, or anchor cables or struts to steel members, wood members, and

rationale.
Exceptions:
B) Properly installed heavy-duty riser clamps seated against steel pipes, heavy
conduit or other compression resistant materials.
C) Toothed strut nuts used in conjunction with a purpose-designed strut material
is very low.)
2) Anchors used for the support of overhead equipment or systems cannot also be used
for the anchorage of seismic restraints. (Rationale: The loads used to size hanger
rods and anchors are based on the weight loads generated by the system. Seismic
3) Anchors to concrete must comply with minimum edge distance, spacing and slab
concrete beams .)
TRANSFERRING FORCES (ELECTRICAL SYSTEM RESTRAINTS)

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4) Screws attached to wood must comply with minimum edge distance, spacing and

result.)
8) Connections between sections of conduit, trays or bus ducts can become critical
factors in evaluating the performance of the system. Unless otherwise informed,
Kinetics Noise Control assumes connections to be of “medium” deformability as
defined by the design code. This is generally appropriate for steel connecting
materials and fittings, brazed connections, and plastic pipe.
TRANSFERRING FORCES (ELECTRICAL SYSTEM RESTRAINTS)


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Cable Clamp Details

Swaged Connector
CABLE CLAMP DETAILS


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SADDLE
CABLE CLIPS
U-Bolt Cable Clips

CORRECT NOT LIKE

INSTALLATION THIS
assembly.
Minimum Minimum
Amount of Rope
Turnback/Inches
1/8 3 3-3/4 3
3/16 3 3-3/4 4.5
1/4 3 4-3/4 15
3/8 3 6-1/2 30
1/2 4 11-1/2 45
CABLE CLAMP DETAILS


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Gripple Connector

as shown.

CABLE CLAMP DETAILS


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DIRECTION OF ARROW

THAT SHOWN)
CONCRETE OR STEEL
STRUCTURE BY OTHERS

GRIPPLE.

CABLE CLAMP DETAILS


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APPROX
1-1/2 CABLE
DIA. PRESET

PRESET DIMENSION
MEASUREMENT
LOCATION

TO REMOVE REMAINING
SLACK FROM CABLE.
CABLE CLAMP DETAILS


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Cable Thimbles

Cable Thimble

CABLE CLAMP DETAILS


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applications.
CABLE CLAMP DETAILS


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Conduit/Tray Attachment Details
Conduit and Cable Tray systems can be supported as independent units or grouped
together and supported on a trapeze structure. Restraints can be installed in the same
manner. When installing restraints, however, it is critical that (except for horizontally
oriented restraint members) they be located in the immediate proximity of a vertical
support member as the support is required to absorb vertical forces that are developed
during the restraint process.
Where cables are illustrated, they can be replaced with a single strut mounted in a similar
fashion where appropriate.

Single Conduit Supported on Hangers
Lateral Restraints
The simplest conduit or tray restraint connection is a lateral restraint fit to a single run. In
the case of conduit, because the forces being restrained are at 90 degrees to the conduit
or tray axis, there is no requirement for a clamped or otherwise rigid connection between
the support clevis and the conduit itself. Of concern is the durability of the hardware used,
the durability of the conduit and the capacity of the hanger rod to resist the reaction loads
generated by the horizontal seismic forces.
Shown below are typical details for clevis hangers fitted with KCHB brace angles and
straps (on the cross bolts).
Top-Restrained Conduit Side-Restrained Conduit
The above description represents the minimum treatment required at each restraint
location, and is appropriate whether cable restraints or struts are used.
CONDUIT/TRAY ATTACHMENT DETAILS


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Axial Restraints
Axial restraints pose more of a problem. Conventional pipe hangers and conduit clamps,
as shown above, do not have the ability to be clamped tightly enough to conduit to
prevent relative axial motion between the two. In order to ensure that the restraint is
rigidly attached to the conduit, a heavy-duty clamp is required, and the tie bolts must be
tightened to spec. Three different types of clamps are shown below.
Again note that the restraints must be located in the immediate vicinity of a vertical
support member.
Clamps must be clamped tightly against the conduit as shown above


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Restraint Arrangements for Electrical Systems Supported on a Trapeze
Typically multiple pieces of conduit, trays and bus ducts are all supported on trapeze bars,
Conduit is usually clamped to the trapeze using a U-bolt or special clamp. Trays and
baskets are connected with clamps as shown below and bus ducts are normally bolted
into place.

When restraining these kinds of systems, positive attachment as shown about is required.
When restraining multiple components of different sizes, the maximum spacing between
restraints cannot exceed the worst-case condition for any of the individual components.
In addition, the restraints must be sized based on the total weight of all of the material


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supported by the trapeze bar. Some caution should be exercised when selecting the bar
to ensure that it has adequate capacity to transfer the load from the conduit or duct runs
to the restraint connections. This is particularly true for some strut arrangements that can
be significantly stiffer in the vertical axis than they are in the horizontal (see illustration
below.) Because the range of applications for trapeze bars is limitless, details will not be
addressed here, but should be reviewed by a competent design professional.

Connections to Trapeze Bars
When installing restraints, typically not all support points will require treatment. For those
trapeze bars that are not restrained either axially or laterally no special connection
treatment is required. Where lateral restraint only is provided at a location, motion
restraint between the conduit runs and the trapeze bar only is required in the lateral
direction. Where axial restraint is required, the conduit, trays or duct need to be clamped
firmly to the trapeze bar so that it cannot slip through the clamp during a seismic event.
The axial clamps shown here are suitable for both axial and lateral loads, and can be
used on all connections. The lateral restraint examples are only appropriate for lateral
loads.
Axial/Lateral Restraint Trapeze Connections
Below are examples of connections that would be suitable for either axial or lateral load
conditions.
Conduit Clamped to a Formed Channel-Based Trapeze Bar


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Piping Clamped to an Angle-Based Trapeze Bar
Cable and Strut Hardware Attachment Options for use with Single

Conduit Hanger Brackets
A typical installation begins with suspending the conduit, and then returning later and
adding restraints. While this eliminates the need to deal with restraints when actually
hanging the conduit, it normally results in more time expended, and possible rework,
during the restraint installation phase. Increasing the diameter of hanger rods for strut-
restrained systems, relocation or duplication of supports for more accessible restraint
installation, and dismantling and reassembling hanger components to make appropriate
connections are the three primary examples of this.
dismantle and reassemble previously installed pipe supports.
Hanger Bracket Reinforcement
When using conventional hangers, the first item required is a spacer bar at the hanger
clevis. This serves two functions. The first is to keep the sides of the support from
collapsing during a seismic event and the second is to offer a hard surface to work against
when attaching and tightening side-mounted restraint brackets and hardware.
Hanger Clevis Showing KSHB Clevis

Hanger Brace Fitted on Tie Bolt


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The brace shown here can be installed without disassembling any previously installed
support hardware.
Also shown in the above drawing are side-mounted cable attachment brackets.
Installation requires the removal and replacement of the tie bolt, which for larger or spring
supported pipes can be awkward and time consuming. This is the preferred installation
arrangement for CCA mounting clips when used on pipes in excess of 12 inches in
diameter.

between the strut and the ground is limited to 45 degrees. See also the sketches below.
For single runs of conduit, the CCA clip can be top mounted. Unless installed during the
initial hanger bracket installation process, this will require the hanger clevis to be
disconnected and reinstalled. This installation is virtually the same as the side-mounted
arrangement with the exception that the CCA clip attaches to the hanger clevis at the
hanger rod location.
Top-Mounted CCA Clip with Cable and Strut Connections


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As an option to the CCA clip, a KSCU clip can be used for side- and top-mounted cable
restraint applications as shown below.

Top- and Side-Mounted KSUA Clips with Cable Connections
The KSCA is the most versatile clip manufactured by Kinetics Noise Control. It can be
mounted in a number of fashions, including both of the above, as well as hanger rod
mounted. In the hanger rod-mounted arrangement, no previously installed hardware need
be disassembled. This frequently makes it the most time-efficient bracket to install in the
field.
While the KSCA is not suitable for extremely heavy-duty applications, it is appropriate for
most applications, even up to relatively high “G” load conditions. See the tables in
Chapter D4 in this manual for sizing components.
Top Mounted Side Mounted
Conventional KSCA Cable Restraint Clip Mounting Arrangements


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KSCA with Strut Attachment Hardware
One of the most common materials for trapezed support of electrical distribution systems
is formed strut-type channel (ex. Unitstrut). Connections to these materials, if using strut
nuts, require the use of toothed nuts. Smooth nuts do not provide adequate resistance
against friction and as such are not acceptable. All nuts must be tightened to their full-
rated torque.


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Both clamps feature two-part construction and “no tool required” installation. The KSRC-
P is comprised of a flexible band punched with a number of slots that is fitted to a clamp
body with an integral seat for the hanger rod. Based on the size of the pipe stiffener and
the hanger rod, the appropriate slot in the clamp band can be used for preliminary


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MEMBER

for Conduit and Cable Tray Restraints
When restraining electrical distribution systems to a structure, there are several different
construction options that impact the restraint selection. Primary among these are the
interface with masonry- or concrete-, steel-, and wood-framed structures. Within each of
these are subgroups that can impact the restraint selection as well.

the structure.
placement.
relative motion between the floor and ceiling of a 10 ft tall room would be about ½”. As a
same surface (mount to ceiling/restrain to ceiling). As a worst case, no more than ¼“
STRUCTURAL ATTACHMENT DETAILS FOR CONDUIT RESTRAINTS


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reinforcement.
components.
Seismic
5:1 Rating
document.

PAGE 2 OF 18 RELEASE DATE 11/6/07

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Ceiling Connections

KSCA Clip with Single ¼ to ½ Anchor
KSUA Clips for ¼ Through ½ Anchors


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(Chapter P10).


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PAGE 6OF 18 RELEASE DATE: 11/6/07

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Through Bolted Connection
Because of the material’s lesser strengths, there are limited methods of attachment to
element.


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wall unit.



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Filled Umbrella-Type Anchor for ¼ and ½ Bolt Sizes
trusses.
Some cautions are appropriate when connecting to these elements, as their primary


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truss without substantial “X” bracing in the immediate area of the restraint attachment


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“X” bracing is normally not required when restraints are connected to the top chord of an


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Shown below is Kinetics Noise Control’s KSBC beam clamp.



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Connections to Wood

a through bolt.


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shown below.

Two Anchor Mounting using a Strut Channel


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KSCA Clips Mounted with Single 1/4 to 1/2 Lag Bolts
KSCU Clips for 1/4 and 1/2 Diameter Lag Screws


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Conclusion
been shown for each option. Except for cases where a connection obviously won’t fit, the
ability to “mix and match” the various end connection combinations shown can be
assumed.


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The IBC and 97 UBC codes allow the omission of seismic restraints for most piping,
conduit and ductwork runs without regard to size but that are located within 12” of the
structure. This figure is 6” for fire sprinkler piping. In order to qualify for this, the following
parameters must be met:
1) The length of all supports on the run measuring from the top anchorage point to the
connection point to the trapeze bar or the top of a singly supported pipe or conduit run
must not exceed 12” (6” for fire piping).
2) Unrestrained free travel of the supported system must be such that over the course of

its movement, contact is not made with any other system, component or structural
element that can result in damage to either the supported system or the object it hit.
3) The top connection to the structure must include a Non-Moment generating connection
to prevent damage to the hanger rod or support strap.
A Non-Moment generating connection is any device that would allow a free flexing action
of the hanger rod or support strap for an unlimited number of cycles without its being
weakened. This motion must be permitted in any direction.
Shown below are typical examples of acceptable Non-Moment generating connections.

Any other device that allows the same freedom of motion is equally acceptable.
A hanger rod rigidly embedded into the underside of a concrete structural slab is not.
SHEET
METAL
ISOLATOR STRAP
CLEARANCE
CHAIN


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Long, Narrow Hallways
Probably the most common issue in the field is how to deal with lateral restraints in long,
narrow hallways. Normally there is considerable congestion in these areas and not
enough room to angle restraints up to the ceiling structure. Often the walls are not

structural and do not offer a surface to which to anchor.
When evaluating halls, the first issue is to determine if either of the walls of the hall is
structural. If either wall is structural, it offers a surface to which the restraints can often be
attached. For structural walls, any relative displacement issues between the wall and the
structure supporting the electrical distribution system in question must be identified. The
maximum permitted relative displacement is ¼ inch, which for most structures correspond
to a difference in elevation of approximately 2 feet (see also the Structural Attachment
Section of this chapter).
Trapeze-Mounted Conduit Restrained to Structural Wall

or Column with a Horizontal Strut (Trays would be similar)


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Trapeze-Supported Bus Duct Restrained to Structural
Wall or Column with an Sloping Strut
Clevis-Supported Conduit Restrained to Structural Wall or Column
“X” or Diagonally Braced Restraint Arrangement


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In cases where only non-structural walls limit access for restraint, it is frequently possible
to penetrate the non-structural wall and shift the lateral restraint device to the opposite
side of the wall or partition as shown here.


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This arrangement is often a convenient way to connect an axial restraint and can occur
both in the horizontal and vertical plane. Often it will be found that when installing bus
ducts, a jog has been added to a run to avoid running into a column or other structural
member. Where this occurs, it offers an easy way to connect an axial restraint.

In congested areas, there is often a double layer of conduit supported off a single trapeze
arrangement. It is possible under some conditions to brace one trapeze bar to the other,
and then restrain the second trapeze bar to the structure. If doing this, the restraint
capacity for the second trapeze bar must be adequate to restrain the total load from both
bars.
Piggyback or Double-Tier Restraint Arrangement


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Restraints for conduits, ducts or trays mounted well below the support structure
that it is not a good idea to support a system from one structural element and restrain it
using another structural element that will undergo significantly different motions.
Restraints fit in this fashion will likely fail or cause the supports for the system that is being
supported to fail. Neither of these outcomes is desirable.
About the only solution to this is to add a support structure for the system that is located
either just above or just below its installed elevation. The system can then be both
attached and restrained to this structure.

forces into the supports.


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TABLE OF CONTENTS
SUSPENDED EQUIPMENT Chapter D10
Seismic Forces Acting On Equipment D10.1
Basic Primer for Suspended Equipment with Cable Restraints D10.2

Pros and Cons of Struts versus Cables D10.3
Layout Requirements for Suspended Equipment
Requirements for Suspended Equipment Restraints D10.4.1

(Definitions and Locating Requirements)
Suspended Equipment Restraint Arrangements D10.4.2
Suspended Equipment Restraint Attachment Details
Transferring Forces D10.5.1
Cable Clamp Details D10.5.2
Suspended Equipment Attachment Details D10.5.3
Structural Attachment Details D10.5.4
Connection Options for Awkward Situations D10.6

SUSPENDED EQUIPMENT RELEASE DATE: 10/12/04

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Seismic Forces Acting on Suspended Equipment
When subjected to an earthquake, Suspended equipment must resist all lateral forces,
without regard to their direction. The restraint components for these systems must resist
pullout and localized structural failures. Unlike piping and ductwork, there are rarely
concerns about the buckling of the equipment. Generally the equipment is assumed to be
rugged enough to maintain it shape throughout the seismic event.
In most cases, equipment is suspended from the deck above on either fixed or isolated
hanger rod systems. On more rare occasions the equipment may be bolted directly to the
underside of the structure without the inclusion of hanger rods. For the later, the

anchorage must be assumed to resist the seismic as well as gravity forces. When
mounted on hanger rods, struts or cables are used to absorb the seismic forces.
When working with suspended equipment, unlike piping and ductwork, the codes in
general do not identify global exemptions. Refer to the code section for specific
exemptions, but in general equipment less than 15 pounds in weight does not require the
installation of “purpose built” seismic restraint componentry. Conventional attachment is
assumed to be adequate.
When installing restraints on hanging equipment, it must be kept from moving in any
horizontal direction. The use of cable restraints or struts can induce uplifting forces at
their attachment point and if these overcome gravity forces, devices to resist this uplift are
also required.
Whether restraining equipment with cables or struts, a minimum of 4 restraints are

needed for each piece of equipment. Cables are typically connected to the equipment
corners (approx) and run in a direction diagonal to the unit. When looking up at the
equipment, each cable should be oriented at approximately 90 degrees to the cables on
either side of it creating a “paddle wheel” look with 4 paddles.
When struts are used, they can be oriented like the cables or they can be oriented as
shown below.
SEISMIC FORCES ACTING ON HANGING EQUIPMENT


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The requirement for 4 struts is to prevent the rotation of the equipment that will occur if 2
struts are used that do not line up exactly with the equipment’s center of gravity.
Ideally, the restraint members should be at as shallow an angle as possible (mostly

horizontal). As the angle becomes steeper (the restraint member becomes more vertical),
the vertical forces in the hanger rods increase. At 45 degrees the vertical force equals the
horizontal force and at 60 degrees the vertical force is 1.73 times the horizontal force.
The net result is that for cable systems or for struts loaded in tension, the uplift force
caused by the cable or strut can be greater than the downward weight load from the
equipment. Depending on the support rod length and stiffness, this can cause the support
rod to buckle. Rod stiffeners are used to protect against this condition and sizing

information is available in Chapter D4 of this manual.
Unlike cables, if struts are used for restraint they can also be loaded in compression. The
hanger rod and its anchorage for these applications must be designed to accommodate
these combined loads. Hanger rod sizing information is also available in Chapter D4 of
this manual.
Proper Use of Force Class Tables when evaluating Hanging Equipment
The Force Class tables presented in Chapter D4 can be used to size cables, struts,
hanger rods and stiffeners for equipment as well as for ductwork. Table 1 and 1A (D4.5)
tailored with appropriate values for the equipment type (note that this may be different
than the values used for piping or ductwork in the same structure) is the first table of
interest.
Because this table is based on weight per foot of the piping or ductwork, it requires a
modification before being used directly. Using the 10 ft OC spacing table, multiply the
values in the weight per ft column by 10 to produce a table that reads directly in pounds.
All values within the output portion of the 10 ft OC table remain unchanged.
The total equipment weight can then be compared to the modified values in the weight
column and the elevation in the structure to the appropriate elevation column to determine
the force class (or lateral restraint in pounds) that is required to properly restrain the
equipment.
Tables 2 and 3 (D4.6) deal with piping and ductwork only and are not required when
working with equipment.
Tables 4a, b, c all deal with sizing hanger rods, rod anchorage, struts and rod stiffeners.
These can be used directly, inputting the weight for the worst case support location and
the Force Class as determined above.


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The final Tables (5 and 5a) in section D4.8 of the manual can also be used directly to size
cables, anchors and anchorage hardware components based on the Force Class or the
lateral restraint force in pounds requirement that was previously determined.
A more detailed explanation of the use of these tables is in section D4.4 of the manual.


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Basic Primer for Suspended Equipment
Failures in piping systems resulting from earthquakes have historically resulted in large
quantities of water or other materials being dumped into occupied spaces of the building
structure. The resulting dollar damage to the building and its contents is often
considerably more than the costs of damage to the building structure itself. In addition,
failure of the building’s mechanical systems can render the structure unoccupiable until
the damage is corrected, and result in major problems for the tenants and/or owners.
Because of the impact that failures of these systems have had in the past, design
requirements for piping systems and interfacing equipment have become much more

stringent.
Within a building structure, there are multitudes of different kinds of systems, each with its
own function and requirements, many of which interface with suspended equipment or are
in the immediate proximity of this equipment. Significant effort must be expended to
ensure that motion of the equipment induced by an earthquake will not damage
surrounding systems or the equipment itself.
This chapter of the manual is a “how to” guide and will deal only with the proper
installation and orientation of restraints and not whether or not they are required by
code, which can be researched further in Chapter D2, or by specification.
This chapter also does not address the sizing of restraint hardware. Section D10.1
and Chapter D4 include sections on sizing componentry based on the design
seismic force and the weight of the system being restrained and should be
consulted for this task.
Process equipment is not directly associated with building operating systems and often
has its own set of requirements. If there are no applicable special requirements, this
equipment should be restrained in a similar fashion to the building mechanical systems.
This manual will not address any special requirements for non-building processes.
BASIC PRIMER FOR SUSPENDED EQUIPMENT


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Pros and Cons of Struts Versus Cables
Both cables and struts have their place in the restraint of equipment. In order to minimize
costs and speed up installation, the differences between the two should be understood.
When restraining equipment there is typically no difference in the number of restraints

needed. This is unlike piping or ductwork where normally a single strut can replace 2
cable assemblies. The difference between equipment and piping/ductwork is that the
equipment is small enough that in addition to swinging laterally from a seismic input, it can
easily rotate. 2 struts acting at 90 degrees to one another cannot resist this rotation.
Under some cases it can be resisted using 3 struts properly aligned, but unless carefully

reviewed a minimum of 4 struts are recommended.
The obvious advantage to struts is that, when space is at a premium, cables angling up to
the ceiling on each side of a piece of equipment may take more space than is available.
Struts can be fitted to one side only, allowing a more narrow packaging arrangement.
There are three significant advantages of cables, where they can be used. First, they
cannot increase the tensile forces in the hanger rod that results from the weight load, so
rod and rod anchorage capacities are not impacted. Second, they are easily set to the
proper length. And third, they are well suited to isolated equipment applications.
To better explain the differences between the systems, it is necessary to look at how
seismic forces are resisted with cables and struts. Shown below are sketches of both
cable-restrained and strut-restrained equipment.
Cable Restrained


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Strut Restrained

The key factor to note is that cables can only be loaded in tension. This means that
seismic forces can only generate compressive loads in the hanger rod. Seismic forces
can, however, load the strut in compression resulting in a tensile load on the hanger rod.
This tensile load is in addition to any deadweight load that may already be supported by
the hanger and is often significantly higher than the original load. This has the potential to
rip the hanger rod out of the support structure and must be considered when sizing
components.
Because of this added tensile component and the resulting impact on the necessary
hanger rod size, most strut manufacturers limit the maximum allowable strut angle (to the
horizontal) to 45 degrees. This is lower than typical allowable angles for cables that often
reach 60 degrees from the horizontal. Although the tables listed in Chapter D4 of this
manual allow the use of higher angles for strut systems, users will find that the penalties
in hanger rod size and anchorage will likely make these higher angles unusable in
practice.
It should also be noted that the hanger rods in tension become seismic elements. This
occurs with struts, but does not with cables. As a result, the system must comply with all
of the anchor requirements specified by ICBO. This includes the use of wedge-type
anchors and embedment depths that are a minimum of 8 anchor diameters. With larger
anchor sizes, floor slab thickness may cause this to become a significant problem.
With both cables and struts, the hanger rods can be loaded in compression. As the
seismic force increases, it eventually overcomes the force of gravity and produces a
buckling load in the hanger rod. It is mandatory in all cases that the rod be able to resist
this force.
There is a wide range of variables involved in determining the need for rod stiffeners to
resist this buckling load. Factors that impact this need are 1) the magnitude of the
compressive force, 2) the weight load carried by the hanger rod, 3) the length of the
hanger rod, 4) the diameter of the hanger rod, and 5) the angle between the restraint strut


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or cable and the horizontal axis.
Tables are included in Chapter D4 of this manual that allow the user to determine if there
is a need for a stiffener and to allow the proper selection if required.
Because uplift occurs, some attention must be given to isolated systems. First, when
using isolators, the location of the isolation element needs to be at the top end of the
hanger rod (close to, but not tight against the ceiling). If placed at the middle of the
hanger rod, the rod/isolator combination will have virtually no resistance to bending and
will quickly buckle under an uplift load.
Second, a limit stop must be fit to the hanger rod, just beneath the hanger such that when

the rod is pushed upward a rigid connection is made between the hanger housing and the
hanger rod that prevents upward motion. This is accomplished by adding a washer and
nut to the hanger rod just below the isolator (see the sketch below).


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Requirements for Suspended Equipment Restraints
Definitions and Locating Requirements
While SMACNA has developed a set of restraint placement criteria based on analytical
review, practical experience, and historical analysis for piping and ductwork, their material
does not address the restraint of equipment. The criterion presented in this manual is
generally based on SMACNA concepts and criteria, except that it is modified to make it
appropriate for use on equipment applications. The only exception to this is that the data
has been extrapolated to higher seismic force levels and hardware capacity limited forces
and is not limited by buckling issues as is the case with piping and ductwork.

With respect to the conceptual restraint arrangement illustrations, many of the SMACNA
concepts are appropriate and are referenced here.
In general, equipment is restrained on a unit by unit basis and the concept of “runs” as
defined in the piping and ductwork sections of the manual are not appropriate. In places
where there are long lengths of pipe or duct integral to the equipment (like radiant
heaters), that portion of the equipment should be restrained in the same manner as piping
or ductwork. More information on this can be found in the piping/ductwork Chapters of the
manual on this.
Also, in some cases, small pieces of equipment may be “hard” mounted into the ductwork.
Under some conditions (see the code section of the manual), these can be treated as part
of the duct and properly restraining the duct will result in acceptable restraint of the
equipment. This is not true if the equipment is connected to the duct using a flexible
material.
Definitions
Lateral A horizontal force acting on the equipment in any direction.
Restraint A device that limits the motion of the equipment in any horizontal direction.
Rod Stiffener A component added to a hanger rod to prevent it from buckling
Restraint Requirements
1) Equipment must be restrained against a lateral force that can act in any direction.
Multiple restraint components may be required to accomplish this task.
2) For long modularized equipment (20 ft or longer), additional restraints should be

installed so the span between the restraints does not exceed 20 ft.


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3) Restraints must be connected to substantial attachment points on the equipment or to
equipment support members that are in turn connected substantially to the equipment.
Hardware in size equal to that identified for the restraint attachment (Chapter D4)
should be used to attach the equipment.
4) All restraints for a given piece of equipment must be the same. (You cannot mix struts
and cables.)
5) With longer hanger rods, rod stiffeners are likely to be required. Refer to the
appropriate table in Chapter D4 to determine: (1) if needed, (2) what size stiffener
material is appropriate, and (3) how frequently it needs to be clamped to the hanger
rod.

6) In addition to possibly requiring rod stiffeners, when struts are used to restrain
equipment, the size of the hanger rod and its anchorage also become critical. Again
refer to the appropriate table in Chapter D4 to determine the minimum allowable size
for the hanger rod and anchor.
7) There is no hanger rod length or component size based exclusion rules for
equipment as there is for piping or ductwork with the following exception. If the
equipment is hard connected to a duct, small enough to be considered part of the
duct (see appropriate code section) and the duct is exempted by one of these rules,
the equipment can also be considered to be exempted.


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Suspended Equipment Restraint Arrangements


on the same job.
the same piece of equipment.
When installing restraints, each individual restraint should be installed perpendicular

(±10 degrees) to the adjacent restraint as viewed from underneath. In addition, the
restraints should be approximately aligned with the center of gravity of the piece of
equipment being restrained. Although it is typical to install restraints at each corner
extending radially outward from the piece of equipment, this arrangement is not
SUSPENDED EQUIPMENT RESTRAINT ARRANGEMENTS


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mandatory. See the sketches below.

(4 Restraint Options, Restraint angles can vary 10 degrees from those shown)
(8 Restraint Options, Restraint angles can vary 10 degrees from those shown)
(4 Strut Option, Restraint angles can vary 10 degrees from those shown)


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In general, when restraining equipment, the component actually being restrained is the
member that supports the equipment rather than the equipment itself. This is normally a
trapeze bar. Because the goal is to restrain the actual equipment, it is necessary that the
restrained element be connected to the equipment in such a way as to transfer the
appropriate forces between the two.
If using the Force Class tables, the minimum bolt size used should equal or exceed the
listed bolt size for a “Bolted” type connection for the restraint (Table 5/5a in section D4.8).
If using a certified calculation as provided by Kinetics Noise Control, the minimum bolt
size will be identified on the calculation document.
Hanging Equipment Restrained with Cables

(Note on these and all sections below, the cables must be oriented in the plan view as
identified earlier in the paper.)
Restraint Examples
For some pieces of equipment that are intended to be suspended, mounting points are
normally provided. An example is an axial flow fan. For these kinds of equipment the
restraints and the supporting hangers are normally connected to these mounting points
directly as shown below. This arrangement works with both isolated and non-isolated
systems. Note that the isolators are mounted with minimal clearance to the structure and
that a travel limiting washer is fitted to the hanger rod just below the isolator in the isolated
arrangement.
Cable Restraints used to restrain an Axial Flow Fan (Non-isolated)


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Cable Restraints used to restrain an Axial Flow Fan (Isolated)
Most equipment however is mounted using a trapeze bar arrangement. There are many
options that exist for the arrangements of restraints used in conjunction with trapeze-
mounted systems. Shown below are several options for both non-isolated and isolated
cable-restrained systems.
\_/ (TOP)
\_/ (BOTTOM)
BOXED
\_/ (TOP)
SUSPENDED
Typical Cable Restraint Arrangements Mounted to a Trapeze (Non-isolated)


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In addition to the conventional \_/ mounting arrangement, where there is sufficient room
above the equipment, and X type of arrangement shown below can often be an attractive
alternative.
X (TOP)
BOXED

X Type Cable Restraint Arrangement Mounted to a Trapeze (Non-isolated)

BOXED
\_/ (TOP)
SUSPENDED
Typical Cable Restraint Arrangements Mounted to a Trapeze (Isolated)


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X (TOP)
TRAPPED
X Type Cable Restraint Arrangements Mounted to a Trapeze (Isolated)

Hanging Equipment Restrained with Struts
(Note on these and all sections below, the cables must be oriented in the plan view as
identified earlier in the paper.)
It is recommended that struts not be used to restrain isolated equipment. Struts will
generate hard connections between the equipment and structure and will greatly reduce
the efficiency of the isolation system. Having said that, in some special situations it may
be possible to design restraint struts with integral isolation elements, but this is tedious
and should be avoided unless drastic measures are required.
Restraint Examples
For a strut-restrained piece of equipment with integral attachment points located away
from the top surface, there is only one common arrangement. It is to connect the restraint
and the support to the attachment point as shown below.
Strut Restraint Arrangement for Axial Fan (Non-Isolated only)
If the connection points for the equipment are on the top surface, the strut can be angled
in the opposite direction as shown below.


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Shown below are 4 options for trapeze-mounted equipment. All are equivalent.

4 Arrangements for the restraint of Trapeze mounted equipment with Struts
Special Cases
Equipment Supported at 2 points
When equipment is supported on only 2 points, caution must be used to ensure that the
restraints are connected in such a way as to prevent lateral motion of the equipment
without allowing it to sway and put undo stress on the hanger rods. Classic examples of
this type of equipment are Unit Heaters.
The condition of concern is illustrated below.


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Possible Sway in Equipment Mounted on 2 Support Hanger Rods
In order to keep this swaying motion from occurring, it is necessary to ensure that on the
axis where swaying can occur, the restraints connect to the equipment at its vertical
center of gravity (approx). This is not necessary on the opposite axis. See Below.
Acceptable Restraint Attachment Elevations for Double Rod Supported Equipment


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Transferring Forces (Suspended Equipment)
conditions in any given installation, suspended systems in general are prone to problems
in this area.
cable ends together or anchor cables or struts to steel members, wood members, and

rationale.
Exceptions:
B) Toothed strut nuts used in conjunction with a purpose-designed strut material
is very low.)
2) Anchors used for the support of overhead equipment cannot also be used for the
anchorage of seismic restraints. (Rationale: The loads used to size hanger rods and
anchors are based on the weight loads generated by the piping system. Seismic
3) Anchors to concrete must comply with minimum edge distance, spacing, and slab
concrete beams.)
4) Screws attached to wood must comply with minimum edge distance, spacing, and
TRANSFERRING FORCES (SUSPENDED EQUIPMENT)


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result.)
TRANSFERRING FORCES (SUSPENDED EQUIPMENT)


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Cable Clamp Details

Swaged Connector
CABLE CLAMP DETAILS


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SADDLE
CABLE CLIPS
U-Bolt Cable Clips

CORRECT NOT LIKE

INSTALLATION THIS
assembly.
Minimum Minimum
Amount of Rope
Turnback/Inches
1/8 3 3-3/4 3
3/16 3 3-3/4 4.5
1/4 3 4-3/4 15
3/8 3 6-1/2 30
1/2 4 11-1/2 45
CABLE CLAMP DETAILS


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Gripple Connector

as shown.

CABLE CLAMP DETAILS


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DIRECTION OF ARROW

THAT SHOWN)
CONCRETE OR STEEL
STRUCTURE BY OTHERS

GRIPPLE.

CABLE CLAMP DETAILS


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APPROX
1-1/2 CABLE
DIA. PRESET

PRESET DIMENSION
MEASUREMENT
LOCATION

TO REMOVE REMAINING
SLACK FROM CABLE.
CABLE CLAMP DETAILS


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Cable Thimbles

Cable Thimble

CABLE CLAMP DETAILS


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applications.
CABLE CLAMP DETAILS


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Suspended Equipment Attachment Details
Equipment is normally supported individually but on rare occasions can be grouped
together and supported on a trapeze structure. Restraints can be installed in the same
manner. When installing restraints, however, it is critical that (except for horizontally
oriented restraint members) they be located in the immediate proximity of a vertical
hanger rod, as the support is required to absorb vertical forces that are developed during
the restraint process.
If the equipment is isolated, cable restraints need to be used in lieu of struts to prevent the
transfer of vibration through the strut into the structure. For non-isolated arrangements,

where cables are illustrated, they can be replaced with a single strut mounted in a similar
fashion.
Equipment with integral support points suspended on Hangers
All pieces of equipment should be suspended on a minimum of two hanger rods and
should be fitted with a minimum of four cable or four strut restraint members.
Common mounting arrangements involve four or more supports and four restraints
oriented as described in Section D10.4.2 A typical detail for an Axial Fan is shown below.
Note that on this isolated case, the spring isolators are mounted close to, but not in direct
contact with the supporting structure. In addition, the hanger rods are fitted with a nut and
washer directly below the hanger box that will limit the maximum upward travel of the rod
(and thus the equipment) to ¼”
When using the double rod arrangement, restraints must connect at an elevation that will
preclude swaying of the equipment. See also section D10.4.2 for more information on
this.
SUSPENDED EQUIPMENT ATTACHMENT DETAILS


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Right and Wrong was to restrain equipment supported on 2 hanger Rods
It is likely that equipment supplied for the installation is not equipped with mounting points
that are aligned with the horizontal CG. If this is the case, additional restraint points will
have to be added by the installation contractor to facilitate this connection.
Restraint Arrangements for Equipment Supported on a Trapeze
Where there is no direct provision on equipment to allow its suspension directly, it can be
supported on trapeze bars. Depending on the installation, it may be preferable to attach
restraints to the top of the equipment rather than to the bottom. This can be done, but
there are two key items that must be addressed when fitting the restraints.
1) The bar that is being laterally restrained must be the bar that is bolted or welded to
the equipment. It is not appropriate to sandwich the equipment between two trapeze
bars, bolt that equipment to the bottom one and restraint the top one. It the top bar is
connected to the restraints, it must also be hard connected to the equipment.
2) A positive connection between the restraint cable or strut and the support hanger rod
(that can withstand both tensile and compressive loads) is required. This means that
the trapeze bar must be locked in place on the hanger rod with nuts both above and
below the trapeze bar. In addition, it means that all components that are between the
connection point of the restraint and the connection point of the hanger must be
positively interconnected.


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When restraining large pieces of equipment, some caution should be exercised when
selecting the trapeze bar to ensure that it has adequate capacity to transfer the horizontal
load from the equipment to the restraint connections. This is particularly true when using
some channel type strut arrangements which can be significantly stiffer in the vertical axis
than they are in the horizontal (see illustration below.) These components are normally
selected based on the deadweight load, but in some cases with current code
requirements, horizontal loads may be 3 to 4 times higher. Because the range of
applications for trapeze bars is limitless, details will not be addressed here, but should be
reviewed by a competent design professional.

Equipment Connections to Trapeze Bars
When installing restraints on large units that use 3 or more trapeze bars for support,
typically not all support points will require treatment. For those trapeze bars that are not
laterally restrained, no special connection treatment is required. Where lateral restraint is
provided at a location, motion between the equipment and the trapeze bar must be
prevented.
This is normally accomplished with the use of hardware that is similar in size to that used
to secure the restraint to the trapeze bar.
Connections should not be made to sheet metal or other non-structural materials in the
equipment without the prior consent of the equipment manufacturer. It should not be
assumed that these are designed to withstand seismic loads and as such, without
confirmation that they are adequate, should be ignored when arranging restraints.
Cable and Strut Hardware Attachment Options for use on equipment

with integral connection points
A typical equipment installation begins with suspending the equipment, and then returning
later and adding restraints. While this eliminates the need to deal with restraints when


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actually hanging the equipment, it normally results in more time expended, and possible
rework, during the restraint installation phase. Increasing the diameter of hanger rods for
strut-restrained systems, relocation or duplication of supports for more accessible restraint
installation, and dismantling and reassembling hanger components to make appropriate
connections are the three primary examples of this.
dismantle and reassemble previously installed supports.

between the strut and the ground is limited to 45 degrees. See the sketches below.
As an option to the CCA clip, a KSCU clip can be used for side-mounted cable restraint
applications as shown below.
Side-Mounted KSUA Clips with Cable Connections


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The KSCA is the most versatile clip manufactured by Kinetics Noise Control. In
applications involving connections to hanger rods, it offers the ability to directly connect to
the hanger rod, offering a significant savings in installation time and cost. Shown here is
both an “inline” arrangement for single axis restraint and a “V” arrangement where biaxial
restraint is needed.

The KSCA is not suitable for extremely heavy-duty applications. This would encompass
larger pieces of equipment in high seismic areas. However, it is appropriate for most
applications. See the tables in Chapter D4 in this manual for sizing components.
One of the most common materials for trapezed support of equipment is formed strut-type
channel (eg. Unitstrut). Connections to these materials, if using strut nuts, require the use
of toothed nuts. Smooth nuts do not provide adequate resistance against friction and as
such are not acceptable. All nuts must be tightened to their full-rated torque.


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Both clamps feature two-part construction and “no tool required” installation. The KSRC-
P is comprised of a flexible band punched with a number of slots that is fit to a clamp body
with an integral seat for the hanger rod. Based on the size of the pipe stiffener and the
hanger rod, the appropriate slot in the clamp band can be used for preliminary


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for Suspended Equipment Restraints
When restraining suspended equipment to a structure, there are several different
construction options that impact the restraint selection. Primary among these are the
interface with masonry- or concrete-, steel-, and wood-framed structures. Within each of
these are subgroups that can impact the restraint selection as well.

the structure.
placement.
relative motion between the floor and ceiling of a 10 ft tall room would be about ½” . As a
same surface (mount to ceiling/restrain to ceiling). As a worst case, no more than ¼“
STRUCTURAL ATTACHMENT DETAILS / SUSPENDED EQUIP RESTRAINTS


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DUBLIN, OHIO, USA • MISSISSAUGA, ONTARIO, CANADA
World Wide Web:
Email:
www.kineticsnoise.com
sales@kineticsnoise.com .5.4 MEMBER


reinforcement.
components.
Seismic
5:1 Rating
document.


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Ceiling Connections

KSCA Clip with Single ¼to ½Anchor
KSCU Clips for ¼Through ½Anchors


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(Chapter P10).


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PAGE 6OF 18 RELEASE DATE: 05/05/04

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Through Bolted Connection
Because of the materials lesser strengths, there are limited methods of attachment to
element.


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wall unit.



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Filled Umbrella-Type Anchor for ¼and ½Bolt Sizes
trusses.
Some cautions are appropriate when connecting to these elements, as their primary


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truss without substantial “ X” bracing in the immediate area of the restraint attachment


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“ X” bracing is normally not required when restraints are connected to the top chord of an


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Shown below is Kinetics Noise Control’ s KSBC beam clamp.



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Connections to Wood

a through bolt.


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shown below.

Two Anchor Mounting using a Strut Channel


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KSCA Clips Mounted with Single 1/4 to 1/2 Lag Bolts
KSCU Clips for 1/4 and 1/2 Diameter Lag Screws


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Conclusion
been shown for each option. Except for cases where a connection obviously won’ t fit, the
ability to “ mix and match” the various end connection combinations shown can be
assumed.


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Note: The options shown below illustrate equipment viewed on a single axis,
Equivalent restraint is however needed on both principle axies.
Long, Narrow Spaces

Probably the most common issue in the field is how to deal with restraints in long, narrow
spaces. Often in these kinds of spaces there is not enough room to angle restraints up to
the ceiling structure. Frequently the walls are not structural and do not offer a surface to
which to anchor.
When evaluating these kinds of spaces, the first issue is to determine if either of the walls
bordering the space are structural. If they one or both are structural, they can offer a
surface to which the restraints can often be attached. For structural walls, any relative
displacement issues between the wall and the structure supporting the pipe must be
identified. The maximum permitted relative displacement is ¼ inch, which for most
structures correspond to a difference in elevation of approximately 2 feet (see also the
structural attachment section of this chapter).
Trapeze-Mounted Equipment Restrained to Structural Wall

or Column with a Strut


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“X” or Diagonally Braced Restraint Arrangements


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In congested areas, It may be possible to restrain a piece of equipment as well as an

associated distribution system with one set of restraints. Care should be used in doing
this to ensure that the the components restrained together have similar properties. For
example:
1) Ductwork can be restained with small AHU units or VAV boxes.
2) Pumps can be restrained with piping, valves or other piping components
3) Piping should not be restrained with AHU’s
4) Ductwork should not be restrained with pumps.
5) Isolated systems must be restrained with other isolated systems
6) If piping or ductwork does not require restraint because of size or proximity to the
ceiling, it cannot be connected to a piece of equipment that does.
When selecting restraints, the restraints must be adequate in capacity to resist the total
load generated by both the equipment and distribution system. These forces can be
determined independently using the Force Class (D4) or other methods and then the
results are simply added together to select components.


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Piggyback Restraint Arrangement
It is possible under some conditions to brace one trapeze bar to the other, and then
restrain the second trapeze bar to the structure. This is shown below:
Double-Tier Restraint Arrangement


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Restraints for Equipment Mounted Well Below the Support Structure
that it is not a good idea to support the equipment from one structural element and
restrain it using another structural element that will undergo significantly different motions.
Restraints fit in this fashion will likely fail or cause the equipment supports to fail. Neither
of these outcomes is desirable.
About the only solution to this is to add a support structure for the equipment that is
located either just above or just below the level of that equipment. The equipment can
then be both attached and restrained to this structure.

forces into the supporting structure.


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TABLE OF CONTENTS
ARCHITECTURAL ELEMENT RESTRIANT SYSTEMS

Floating Floor Systems
Floating Floor Seismic Restraint Design D.11.1
Isolated Ceiling Systems
Isolated Ceiling Seismic Restraint Design D.11.2
Isolated Wall Systems
Isolated Wall Seismic Restraint Design D.11.3
TABLE OF CONTENTS
ARCHITECTURAL ELEMENT RESTRAINT SYSTEMS RELEASE DATE: 10/28/04

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Floating Floor Seismic Restraint Design
Floating floors, by nature of their design, can move horizontally when subjected to
earthquakes. Large lateral movements could generate instability in the isolation pads or
springs and must be prevented. The amount and type of restraint required is a function of
the design earthquake and the properties of both the isolation system and the floor
design.
Restraint Types

There are two basic types of floating floor seismic restraints – perimeter and interior. A
perimeter isolation system consists of shock-absorbing pads spaced around the perimeter
of the floor and attached to structural supports. These pads prevent direct contact
between the floating floor and the supporting structural elements and their flexibility
reduces the impact load on the floor and provides some damping for the horizontal
motion. Ideally, the structural support will be integral with the building structural system,
consisting of a structural wall or curb around the floor perimeter. Alternatively, the support
system can be installed after the structure is complete by anchoring structural angles to
the structural system. Both types of restraints are shown in Figures 1 and 2.
Interior restraints are embedded within the floating floor. Each restraint restricts seismic
motion in all horizontal directions, reducing the number of restraints required. Large floors
often require internal restraints to prevent buckling of the floor during an earthquake.
Another common application is for a floor without perimeter supports where the use of
angles is not desired. Figures 3 and 4 show typical installations of internal seismic
restraints.
Restraint Selection
The choice of internal versus external seismic restraint most often depends upon the size
of the floor to be restrained (preventing buckling in the floor system) and the presence or
absence of a perimeter structural support. Kinetics Noise Control or the Structural
Engineer or Architect of Record for the project should determine the buckling
characteristics of the floor.
If a perimeter system is selected, the ability of any supporting structure (curb or wall) to
carry the applied seismic load must be determined by the Structural Engineer of Record.
If no adequate support is available, a support can be designed and supplied by Kinetics.
The perimeter isolation system usually consists of twelve-inch wide neoprene pads
spaced five to six feet on center, with the actual spacing determined by calculation.
Kinetics PIB is placed between the pads to eliminate any flanking path for noise.
Internal restraints are used when they are required to prevent buckling of the floor or
FLOATING FLOOR SEISMIC RESTRAINT DESIGN


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when no adequate perimeter support is available. The restraints are placed before the
floor is formed in either the final position (RIM-type floor) or on the structural slab (lift-slab
system). The outer portion of the restraint is attached to the floating floor while the inner
portion is attached to the structural slab. Neoprene pads integral to the support provide
the impact cushioning and damping required for proper restraint.
STRUCTURAL SUPPORT (WALL OR CURB)

KINETICS NEOPRENE SEISMIC RESTRAINT
KINETICS ISOLATION SYSTEM (RIM SHOWN)

BUILT-UP FLOATING FLOOR
STRUCTURAL FLOOR
Figure 1. Floating Floor Perimeter Isolation w/Structural Support.
KINETICS STRUCTURAL SUPPORT
KINETICS NEOPRENE SEISM IC RESTRAINT

KINETICS ISOLATION SYSTEM (RI M SHOWN)
BUILT-UP FLOATING FLOOR
STRUCTURAL FLOOR
Figure 2. Floating Floor Perimeter Isolation w/Kinetics Structural Support.

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a) Initial Position b) Raised Position
Figure 3. Internal Restraint for Lift-Slab System.
Figure 4. Internal Restraint for Roll-Out System.


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Isolated Ceiling Seismic Restraint Design
Isolated ceilings typically weigh between 2 and 7.5 pounds per square ft and are made of
1, 2 or 3 layers of drywall. Over larger areas, the total weight of a ceiling system can
become significant and the resulting seismic forces can be significant as well. In addition,
it is not uncommon for ceilings to have a stepped or otherwise non-flat profile that can
limit the ability to transfer these forces out to the perimeter. Even where this is not the
case, significant crushing can occur along the perimeter on even moderately sized
ceilings if no centralized restraint system is provided. Because of this, for ceilings either
whose length or width exceeds 15 ft, internal seismic restraint elements are
recommended.

Even on smaller ceilings in some cases, equipment or light fixtures can add to the seismic
loading that must be resisted and requires that appropriately sized restraints be fitted.
Restraint Types
Typically cable restraint systems are used to transfer seismic forces from the isolated
ceiling to the structure in much the same way as with piping or duct systems. Because
the ceilings are isolated, there is a need for cables rather than struts. An added issue
when fitting restraint cables is that the cables must typically be installed and adjusted prior
to the installation of the ceiling. As the ceiling adds significant weight, the springs that
support it will deflect a noticeable additional amount under that weight. Care must be
taken to ensure that this added deflection does not take all of the clearance out of the
restraint cables and in so doing, generate a mechanical “short” for vibrations.
In some cases, seismically rated, housed ceiling isolators can be used, These are tolerant
of the added deflection which occurs with the addition of the drywall. These however may
not be suitable for all applications. More commonly conventional cable restraints are used
with special attention given to ensure that no mechanical shorts will occur.
Seismically Rated KSCH Ceiling Support Isolator


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This isolator bolts directly to wood or concrete and offers positive seismic restraint for a
broad range of applications. Included is a saddle that fully contains the CR channel
commonly used to support isolated drywall ceiling systems. This saddle prevents side to
side motion of the channel in its basic configuration. For use in seismic applications, it
must be fitted with an optional #10 screw to prevent the channel from sliding through the
saddle. See also the picture below.

ADDED #10 SCREW
These Isolators are capable of supporting loads up to 140 lb per isolator while at the same
time offer a horizontal restraint capacity of 100 lb each.
Typical KSCH Installation


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Seismically Rated ICW Ceiling Support Hanger

Where the isolated ceiling is suspended below the structure a significant distance, the
ICW Seismic Isolator can often be used. Unless the ceiling grid is tight up against the
underside of the Isolator, it is necessary to incorporate 2mm KSCU cable assemblies to
protect the hanger rod as shown below.
The cable restraint assemblies must connect to the hanger rod within ½” of the underside
of the ICW restraint bracket as shown, but the actual exposed length of the hanger rod
can be as much as 12”. Connections to the ceiling grid must be with a ¼” bolt (min).


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This restraint device is rated for 60 lb in any direction.
Restraining Ceiling Systems with Cables
Ceiling systems can be restrained using cable restraints in fashion similar to that shown
above, but with the restraints connected directly to structure. When this is done, the
“Force Class” rules in chapter D4 of this manual apply.
When installed, it should be assumed that the ceiling will drop ½” - 1” for most systems
and provisions must be made in the cable tightness to accommodate this. It is generally
recommended that the cable be put in on a shallow slope not to exceed 15 degrees from
the horizontal. In addition the grid should be deflected downward manually when
installing the cables to approximately the expected deflection amount. In that condition,
the cable should be slightly loose (1/16” to 3/16” lateral motion allowed).
In addition, the isolation hangers should be mounted close to, but not in contact with the
underside of the ceiling structure. Maximum clearance under load should not exceed
1/8”.
The recommended restraint kit for ceiling restraint is the 2mm KSCU kit. Each kit
contains 2 cables and 2 kits are required at each restraint location. Maximum lateral
capacity at each restraint location for this kit is 200 lb.


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Isolated Wall Seismic Restraint Design
Proper installation of isolated walls requires that the wall not only be resiliently supported,
but that they are also resiliently stabilized. Because the walls are not part of the building
structure, they do not have a membrane to support the upper edges. This makes them
inherently unstable. They are also subject to lateral loads from contact with other objects
or due to the attachment of wall mounted components to them. The requirement for
stabilization is compounded in seismic areas where the walls can be exposed to
significant lateral acceleration forces.

Because masonry walls require high compressive loads to prevent internal buckling and
because they possess a high level of mass, the requirement for restraint becomes more
critical. The stabilizing compressive load present in a load bearing wall is not present in a
free standing wall rendering them easily susceptible to seismic damage.
To determine the amount of support required by the wall several factors must be taken
into account. These are: 1) the amount of natural support dictated by the room geometry
(corners and intersections), 2) the stability provided by the type of construction, 3) the unit
mass of the isolated wall and 4) the anticipated lateral loading to which the wall may be
subjected.
Beginning with the rooms "natural support", it is safe to assume that any corner or
intersection point that occurs in the isolated wall system where at least 2 of the
intersecting walls extend a distance equal to 50% of the walls height can be considered to
form a natural restraint. For example, a 10 ft x 10 ft room with 8 ft tall isolated walls can
be considered to have 4 naturally supported corners. However, if we consider a wall with
a 6 in long jog in its center, the jog (since it's length is less than 50% of the wall height)
cannot be considered to be a natural support.
The various methods used to construct isolated walls have different levels of resistance
against buckling. For example, a masonry wall that is not subjected to weight bearing
loads is quite weak in buckling, where a masonry wall that is bearing weight can be quite
resistant to it. In non-weight bearing applications, frame construction is generally more
resistant to vertical buckling loads than masonry. On the other hand, frame construction
is also generally weaker than masonry walls when evaluating the transfer of loads along
the length of the wall. This is because, apart from the top and bottom, the framing
members do not normally run in the horizontal axis.
The surface mass of a wall works in conjunction with seismic accelerations to generate
buckling and toppling forces. Lower surface mass framed walls are much less subject to
damage from seismic loads than are heavy masonry ones.
Floating walls subjected to horizontal loads can buckle or topple in the vertical plane or

PAGE 1 of 5 RELEASE DATE: 11/30/04

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can buckle along their length. Illustrations of the vertical failure modes are shown below.
The first case (buckling) is the result of the wall being restrained top and bottom but with
too great a vertical center distance between restraints. The second (toppling) is the result
of inadequate restraint at the top.
BUCKLING TOPPLING
AT CENTER

The buckling mode along the walls length is similar to the buckling case above except that
it occurs in the horizontal plane. It most commonly occurs along the top edge of a wall
where there is no positive continuous restraint fitted and where the horizontal distance
between localized restraints is excessive.
All walls must be designed to resist the anticipated seismic forces (as a minimum) and if
there are known or anticipated forces that may result from other factors which exceed the
seismic loads, they must be identified and used for sizing the appropriate restraint
devices. This document will identify the restraints necessary based on seismic
requirements only.
In the case of seismic events, the driving force is created by horizontal accelerations
acting on the mass of the wall. Resisting this loading are the restraints and the buckling
strength of the wall itself. The wall's buckling strength and mass can be determined for
commonly used building cross sections and using this, the wall's natural ability to
withstand horizontal accelerations can be determined. This resistance/force relationship
can then be used to determine the maximum allowable span length between restraints.
Once the spacing is determined, the actual load that the restraint must be capable of
handling can be quickly determined by dividing the supported wall mass among the
supporting restraints and applying the appropriate acceleration factor to it.
As wall restraints/isolators include no running clearance, these devices must be capable

of developing this force while still maintaining a low enough natural frequency to ensure


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the isolation characteristics of the wall.
As the natural frequency of a system is a function of its supported mass and spring rate
(measured as deflection if the spring is oriented vertically). A restraint should be selected
based on its having the desired spring rate in the unloaded condition. It is also desirable
to have a relatively short working range to minimize wall motion during a seismic event.
Restraints with a graduated spring rate such as occur in neoprene pads with simple
shapes tend to be ideal for this.
It is always worthy of note to indicate that when isolators are oriented horizontally and are
not affected by gravity, the installed deflection is not part of the design requirement. This

is because natural frequency is a function of mass and spring rate and not of deflection.
Based on the trade-off between the inherent or natural strength of isolated walls of various
constructions and their mass, the following table has been generated. It provides a
recommended maximum spacing for restraints on both the vertical and horizontal axis
based on seismic accelerations and is broken down by wall type. It also lists the
approximate maximum load that the restraint is likely to see.
Seismic Acceleration in G's
Acceleration Factor 2 1 0.75 0.4 0.2 0.1Maximum
Restraint
Type Wall Horiz Vert Horiz Vert Horiz Vert Horiz Vert Horiz Vert Horiz Vert Force
Masonry CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) CD (in) lbs
6" Block/Hollow 22 22 31 31 36 36 49 49 70 70 99 99 509
6" Block/Sand Filled 26 26 36 36 42 42 57 57 81 81 114 114 509
8" Block/Hollow 23 23 33 33 38 38 52 52 73 73 104 104 749
12" Block/Hollow 24 24 34 34 40 40 54 54 77 77 109 109 1232
Frame/Drywall
16" Centers / 1/2" Drywall 22 78 32 111 37 120 50 120 71 120 71 120 61
16" Centers / 1" Drywall 17 60 24 85 28 98 38 120 54 120 77 120 61
16" Centers / 1-1/2" Drywall 14 51 20 72 24 83 32 113 46 120 65 120 61
16" Centers / 5/8" Drywall 21 72 29 102 34 118 46 120 65 120 93 120 61
16" Centers / 1-1/4" Drywall 16 55 22 77 26 89 35 120 50 120 70 120 61
16" Centers / 1-7/8" Drywall 13 46 19 65 21 75 29 102 41 120 59 120 61
24" Centers / 1/2" Drywall 24 67 33 95 39 110 53 120 75 120 75 120 50

24" Centers / 1" Drywall 18 51 25 72 29 83 40 113 56 120 79 120 50
24" Centers / 1-1/2" Drywall 15 42 21 60 24 69 33 94 47 120 66 120 50
24" Centers / 5/8" Drywall 22 62 31 87 35 101 48 120 68 120 97 120 50
24" Centers / 1-1/4" Drywall 16 46 23 65 26 75 36 102 51 120 72 120 50
24" Centers / 1-7/8" Drywall 13 38 19 54 22 62 30 85 42 120 60 120 50
To ensure that the wall is not damaged when subjected to the max loading condition, total
design deflection in the restraint device should be limited to 1/4" (max).


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The following assumptions were used in compiling these tables:
The masonry construction assumes a tensile strength of 275 PSI in the mortar.
The frame construction assumes the use of 20 ga metal 2 x 4 studs. It also requires that
if the frame wall exceeds 120" in height, 2-20 ga metal 2 x 4 studs are interlocked and
sandwiched between 2-20 ga 2 x 4 metal framing channels. These must run horizontally
along the walls length and are oriented to align the ends of the upper and lower vertically
oriented studs. For all frame walls a single 20 ga metal 2 x 4 stud is welded or screwed to
a 20 ga 2 x 4 metal framing channel to form the top plate of the wall.

MIN FRAME WALL
MIN FRAME WALL
MID SPAN
HEADER
STIFFENER
CONSTRUCTION
CONSTRUCTION
Wall Top and Bottom Restraints
Isolated Masonry walls are normally set into a pocket formed by extending the recess in
the structural slab allowed for installation of a floating floor beyond the perimeter of the
floating floor itself. When used, this gap is sized to allow an isolated wall to penetrate the
floating floor and sit on its own set of support pads. As an option, masonry walls can also
be set onto the perimeter of the floating floor and doweled to it in a fashion that can resist
seismic shear loads at the wall’s base.
Framed walls are frequently supported either on the perimeter of the floating floor as
mentioned above or are mounted on their own set of isolation pads that are spaced at
regular intervals down the length of the base rail. In either case, the anchors used to
connect the wall to the floor must be sized to resist the seismic shear loads that can occur
at the base of the wall. Normal spacings as specified by Kinetics Noise Control are
adequate for this task in all seismic conditions
As the isolated wall is intended to reduce the flow of noise from one space to another, the
tops of these walls will normally abut the underside of a floor or ceiling element. These
connections should be sealed to resist the flow of sound and frequently this is
accomplished via the use of rubber faced angles that hard attach to the structure and
cradle the top of the wall. If these are used for restraint purposes, they must be sized
based on the expected load. Kinetics Noise Control offers the IPRB, neoprene faced
angle brackets that are frequently used for this task.


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Seismic Sway Braces for Masonry
For the interior expanse of isolated walls or where the IPRB does not possess adequate
capacity on its own to restrain the top, there are several products that can be used. The
Kinetics PSB sway brace is commonly used for the restraint of isolated walls made of
masonry. These are rated with capacities up to 2000 lb.

PSB Sway Brace
An additional option for lighter duty applications is the KWSB. This is lighter duty and is
made to connect to the framing members that make up the structure of the isolated wall.
Capacities on KWSB go up to 50 lb.
Probably the best solution for gauge material is the Isomax wall clip. This is designed to
both support a wall and when spaced in a 24” x 48” array, can provide adequate restraint
for walls made up of as much as 3 layers of 5/8” drywall in applications as high as .5 G.
The Seismic rating can increase with reduced spacing if need be.
IsoMax Wall Isolation Clip


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CHAPTER D12
RECOMMENDED SEISMIC SPECIFICATIONS
TABLE OF CONTENTS

KINETICS Long Form Seismic Specification D12.1

RECOMMENDED SEISMIC SPECIFICATIONS RELEASE DATE: 09/20/04

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KINETICS LONG FORM SEISMIC SPECIFICATION
1.0 General
1.01 Related Work Specified Elsewhere

(Vibration Isolation portion of specs, fill in as required)
1.02 Definitions
1) Av: Effective peak velocity related acceleration coefficient BOCA, SBC Code.
2) S1: Mapped Long Period Seismic acceleration coefficient IBC, TI-809-04 Code.

3) Ss: Mapped Short Period Seismic acceleration coefficient IBC, TI-809-04 Code.
4) v: Zonal Velocity coefficient NBC-Canada
5) SMACNA: (Sheet Metal and Air Conditioning Contractors National Association) has
developed Guidelines for the installation of restraints for piping and duct systems.
6) VISCMA: (Vibration Isolation and Seismic Control Manufactures Association) has
developed Testing and Rating Standards for Seismic Restraint Components that
comply with Code and ASHRAE based requirements.
7) Z: Seismic Zone defines Seismic Coefficient Ca used by UBC Code.
1.03 Performance Requirements
1) Design Ground Acceleration Coefficient (Av, Ss, v or Z depending on Code =X.XX )

2) (If IBC or TI-809-04) Design Long Period Ground Acceleration Coefficient (S1
=X.XX )
3) Design Soil Type = (Sa, Sb, Sc, Sd) as appropriate. (If NBC Canada, the Foundation
Factor)
4) Importance or Performance Factor appropriate to structure = X.XX
5) If UBC Zone 4, Proximity to Fault and, if less than 10km, Fault Type
6) Equipment Schedule (IBC, TI-808-04, 97UBC) The Mechanical Engineer of record
will provide a comprehensive Equipment Schedule indication individual equipment
importance factors, Ip, (including equipment whose importance factor, Ip, may be
increased by proximity to essential life safety or hazardous components),
equipment elevation both in the structure and(if floor mounted, relative to the floor),
roof elevation and structural interface material, i.e., anchored to concrete, bolted or
welded to steel.
7) Schedule or drawings indicating critical (Ip=1.5) Duct/Piping systems, including
systems whose importance factor may be increased by proximity to critical
components.
1.04 Submittals
1) Product Data: Include Seismic Rating Curve for each seismically rated isolator or


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restraint component
2) Samples: The contractor shall submit samples of specified seismic snubber
devices upon request of the engineer for approval
3) Shop Drawings: Include the following:
A) Design Calculations: Calculate requirements for selecting vibration
isolators and seismic restraints and for designing vibration isolation
bases. Certification documents to be signed and sealed by a qualified
Professional Engineer with at least 5 years experience in the design of
seismic restraints.
B) Vibration Isolation Bases: Dimensional drawings including anchorage
and attachments to structure and to supported equipment. Include

auxiliary motor slides and rails, base weights, equipment static loads.
C) Seismic-Restraint Details: Detail submittal drawings of seismic restraints
and snubbers. Show anchorage details and indicate quantity, diameter,
and depth of penetration of anchors.
D) Submittals for Interlocking Snubbers: Include ratings for horizontal,
vertical and combined loads.
E) Equipment Manufacturer Seismic Qualification Certification: The
Equipment Manufacturer must submit certification that each piece of
provided equipment will withstand seismic forces identified in
"Performance Requirements" Article above. Include the following:
1) Basis for Certification: Indicate whether the “withstand”

certification is based on actual test of assembled components or
on calculations.
2) Indicate the equipment is certified to be durable enough to:
A) structurally resist the design forces and/or
B) will also remain functional after the seismic event.
F) Dimensioned Outline Drawings of Equipment Unit: Identify center of

gravity and locate and describe mounting and anchorage provisions.
G) Detailed description of the assumed equipment anchorage devices on

which the certification is based.
1.05 Work Furnished But Not Installed
1) The materials and systems specified in this section shall be purchased by the
mechanical contractor from a single seismic snubber restraint materials
manufacturer to assure sole source responsibility for the performance of the seismic
restraints used.


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2) The materials and systems specified in this section can, at the contractor’
s option,
be installed by the subcontractor who installs the mechanical equipment, piping, or
ductwork.
1.06 Coordination
1) Coordinate size, shape, reinforcement and locate cast in place anchor-bolt inserts
for concrete Inertia bases. 3000 psi min Concrete and/or formwork as needed is
provided by others.
2) Coordinate design of roof curbs and equipment supports to be compatible with
equipment parameters.
1.07 Description of System

1) It shall be understood that the requirements of this seismic restraint section are in
addition to other requirements as specified elsewhere for the support and
attachment of equipment and mechanical services, and for the vibration isolation of
same equipment. Nothing on the project drawings or specifications shall be
interpreted as justification to waive the requirements of this seismic restraint section.
2) The work under this section shall include furnishing all labor, materials, tools,
appliances, and equipment, and performing all operations necessary for the
complete execution of the installation of seismic snubber restraint assemblies as
shown, detailed, and/or scheduled on the drawing and/or specified in this section of
the specifications
3) All seismic snubber restraint assemblies shall meet the following minimum
requirements:
A) The snubber shall include a high quality elastomeric element that will
ensure that no un-cushioned shock can occur.
B) It shall be possible to visually inspect the resilient material for damage
and replace it if necessary.
C) Resilient material used in snubber assemblies to be a minimum of 0.25”
(6 mm) thick.
D) Resilient material used in snubber grommets to be a minimum of 0.12”
(3 mm) thick.
E) All Interlocking Snubbers to include a maximum air gap of .25 in (6mm).
F) Assembly must be designed to offer seismic restraint in all directions,
unless otherwise noted below.
G) Seismic restraint capacities to be verified by an independent test
laboratory or certified by an experienced registered Professional
Engineer to ensure that the design intent of this specification is realized.
4) Vibration Isolation Bases: Dimensional drawings including anchorage and
attachments to structure and to supported equipment. Include auxiliary motor slides
1.08 System Design


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1) Seismic snubber manufacturer shall be responsible for the structural design of
attachment hardware as required to attach snubbers to both the equipment and
supporting structure on vibration isolated equipment, or to directly attach equipment
to the building structure for non-isolated equipment.
2) The contractor shall furnish a complete set of approved shop drawings of all
mechanical and electrical equipment which is to be restrained to the seismic
restraint manufacturer, from which the selection and design of seismic restraint
devices and/or attachment hardware will be completed. The shop drawings
furnished shall include, at a minimum, basic equipment layout, length and width
dimensions, installed operating weights of the equipment to be restrained and the
distribution of weight at the restraint points.

3) All piping and ductwork is to be restrained to meet code requirements. Spacing
between restraints is not to exceed the allowable spacing listed in the latest revision
of the SMACNA manual (Sheet Metal and Air Conditioning Contractors National
Association, Inc.) “Seismic Restraint Manual Guidelines for Mechanical Systems”,
Second Edition, 1998. At a minimum, the seismic restraint manufacturer will provide
documentation on maximum restraint spacing for various cable sizes and anchors,
as well as ‘ worst case’reaction loads at restraint locations. In addition, seismic
restraint manufacturer will provide support documentation containing adequate
information to allow the installation contractor to make reasonable field modifications
to suit special case conditions.
4) The contractor shall ensure that all housekeeping pads used are adequately
reinforced and are properly attached to the building structural flooring, so to
withstand anticipated seismic forces. In addition, the size of the housekeeping pad
is to be coordinated with the seismic restraint manufacturer so to ensure that
adequate edge distances exist in order to obtain desired design anchor capabilities.
1.09 Alternate Systems
1) Provisions of the General Conditions and Supplemental Conditions of the

specifications shall govern the use of alternate systems to those specified.
2) Manufacturers not listed as approved in “Part 2 Materials” of this section must
secure approval to bid a minimum of ten (10) days prior to the project bid date.
3) Uncertified internal equipment seismic restraint systems are disallowed for use on
this project.
1.10 Installation
1) Installation of all seismic restraint materials specified herein shall be accomplished

following the manufacturer’ s written instructions. Installation instructions shall be
submitted to the engineer for approval prior to the beginning of the work.
2.0 Materials
2.01 Source of Materials


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1) All seismic snubbers and combination snubber / vibration isolation materials
specified herein shall be provided by a single manufacturer to assure sole source
responsibility for the proper performance of the materials used. Manufacturer is to
be a member of VISCMA (Vibration Isolation and Seismic Control Manufacturers
Association).
2) Mechanical anchor types and sizes are to be per the design data as provided by the
seismic restraint manufacturer.
3) Materials and systems specified herein and detailed or scheduled on the drawings
are based upon materials manufactured by Kinetics Noise Control, Inc. Materials
and systems provided by other manufacturers are acceptable, provided that they
meet all requirements as listed in this specification.

4) Where not protected by a shield, resilient materials shall be easy to visually inspect
for damage.
2.02 Factory Finishes
1) Manufacturer's standard prime-coat finish ready for field painting.

2) Finish: Manufacturer's standard paint applied to factory-assembled and -tested
equipment before shipping.
A) Powder coating on springs and housings.
B) All hardware shall be electrogalvanized. Hot-dip galvanize or powder
coat metal housings for exterior use.
C) Enamel or powder coat metal components on isolators for interior use.
D) Color-code or otherwise mark vibration isolation and seismic-control
devices to indicate capacity range.
2.03 Seismic Snubber Types
Isolator / Snubber Types contained herein are per ASHRAE (American Society of
Heating, Refrigerating and Air-Conditioning Engineers, Inc.) Handbook, 2003 HVAC
Applications, Chapter 54 “Seismic and Wind Restraint Design”, Pages 12 and 13.
1) Type A): Coil Spring Isolator Incorporated Within A Ductile Iron Or Cast
Aluminum Housing
A) Cast iron or aluminum housings are brittle when subjected to shock
loading and are therefore not approved for seismic restraint
applications.
2) Type B): Coil Spring Isolator Incorporated Within A Steel Housing
A) Spring isolators shall be seismic control restrained spring isolators,
incorporating a single or multiple coil spring element, having all of the
characteristics of free standing coil spring isolators as specified in the
vibration isolation portion of this specification. Springs shall be
restrained using a housing engineered to limit both lateral and vertical


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movement of the supported equipment during an earthquake without
degrading the vibration isolation capabilities of the spring during normal
equipment operating conditions.
B) Vibration isolators shall incorporate a steel housing and neoprene
snubbing grommet system designed to limit motion to no more than ¼”
(6 mm) in any direction and to prevent any direct metal-to-metal contact
between the supported member and the fixed restraint housing. The
restraining system shall be designed to withstand the seismic design
forces in any lateral or vertical direction without yield or failure. Where
the capacity of the anchorage hardware in concrete is inadequate for
the required seismic loadings, a steel adapter base plate to allow the
addition of more or larger anchors will be fitted to fulfill these

requirements. In addition to the primary isolation coil spring, the load
path will include a minimum ¼”(6 mm) thick neoprene pad.
C) Spring elements shall be color coded or otherwise easily identified.
Springs shall have a lateral stiffness greater than 1.2 times the rated
vertical stiffness and shall be designed to provide a minimum of 50%
overload capacity. Non-welded spring elements shall be epoxy powder
coated and shall have a minimum of a 1000 hour rating when tested in
accordance with ASTM B-117.
D) To facilitate servicing, the isolator will be designed in such a way that
the coil spring element can be removed without the requirement to lift or
otherwise disturb the supported equipment.
E) Spring isolators shall be Model FHS as manufactured by Kinetics Noise
Control, or by other manufacturers who can meet the requirements as
listed in sections 1.04 through 1.09 inclusive, and sections 2.01, 2.02
and 2.03 (2).
3) Type C): Coil Spring Isolator Incorporated Within A Steel Housing
A) Spring isolators shall be seismic control restrained spring isolators,
incorporating one or more coil spring elements, having all of the
characteristics of free standing coil spring isolators per the vibration
isolation section of this specification, for equipment which is subject to
load variations and/or large external forces. Isolators shall consist of
one or more laterally stable steel coil springs assembled into fabricated
welded steel housings designed to limit movement of the supported
equipment in all directions.
B) Housing assembly shall be made of fabricated steel members and shall
consist of a top load plate complete with adjusting and leveling bolts,
adjustable vertical restraints, isolation washers, and a bottom load plate
with internal non-skid isolation pads and holes for anchoring the housing
to the supporting structure. Housing shall be hot dipped galvanized for
outdoor corrosion resistance. Housing shall be designed to provide a
constant free and operating height within 1/8”(3 mm).
C) The isolator housing shall be designed to withstand the project design


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seismic forces in all directions.
D) Coil spring elements shall be selected to provide static deflections as
shown on the vibration isolation schedule or as indicated or required in
the project documents. Spring elements shall be color coded or
otherwise easily identified. Springs shall have a lateral stiffness greater
than 1.2 times the rated vertical stiffness and shall be designed to
provide a minimum of 50% overload capacity. Non-welded spring
elements shall be epoxy powder coated and shall have a minimum of a
1000 hour rating when tested in accordance with ASTM B-117.
E) Spring isolators shall be Model FLSS as manufactured by Kinetics Noise

and 2.03 (3)
4) Type D): Coil Spring Isolator Incorporated With Integral Seismic Restraint
A) Spring isolators shall be single or multiple coil spring elements which
have all of the characteristics of free standing coil spring isolators as
specified in the vibration isolation portion of this specification,
incorporating lateral and vertically restrained seismic housing
assemblies. Spring elements shall be readily replaceable without the
need to lift or remove the supported equipment.
B) Restraint housing shall be sized to meet or exceed the force
requirements of the application and shall have the capability of
accepting coil springs of various sizes, capacities, and deflections as
required to meet the required isolation criteria. All spring forces shall be
contained within the coil / housing assembly, and the restraint anchoring
hardware shall not be exposed to spring generated forces under
conditions of no seismic force. Spring element leveling adjustment shall
be accessible from above and suitable for use with a conventional
pneumatic or electric impact wrench.
C) Restraint element shall incorporate a steel housing with elastomeric
elements at all dynamic contact points. Elastomeric elements shall be
replaceable. Restraint shall allow ¼”(6 mm) free motion in any direction
from the neutral position. Restraint shall have an overturning factor
(ratio of effective lateral snubber height to short axis anchor spacing) of
0.33 or less to ensure optimum anchorage capacity.
D) Spring isolators shall be Model FMS as manufactured by Kinetics Noise
and 2.03 (4).
5) Type E): All Direction Neoprene Isolator
A) Vibration Isolators shall be neoprene, molded from oil resistant
compounds, designed to operate within the strain limits of the isolator so
to provide the maximum isolation and longest life expectancy possible


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using neoprene compounds. Isolators shall include encapsulated cast-
in-place top steel load transfer plate for bolting to equipment and a steel
base plate with anchor holes for bolting to the supporting structure.
Ductile iron or cast aluminum components are not acceptable
alternatives and shall not be used due to brittleness when subjected to
shock loading.
B) Isolator shall be capable of withstanding the design seismic loads in all
directions with no metal-to-metal contact.
C) Isolator shall have minimum operating static deflections as shown on the
project Vibration Isolation Schedule or as otherwise indicated in the
project documents and shall not exceed published load capacities.

D) Neoprene isolators shall be Model RQ as manufactured by Kinetics
Noise Control, or by other manufacturers who can meet the
requirements as listed in sections 1.04 through 1.09 inclusive, and
sections 2.01, 2.02 and 2.03 (5)
6) Type F): Light Capacity All Direction 3-Axis External Seismic Snubber
Assembly
A) Equipment shall be restrained against excessive movement during a
seismic event by the use of 3-axis resilient snubbers, designed to
withstand the project required seismic forces. A minimum of two (2)
snubbers are to be used at each equipment installation, oriented to
effectively restrain the isolated equipment in all three directions, and
additional snubbers shall be used as required by seismic design
conditions.
B) Snubbers shall be of interlocking steel construction and shall be
attached to the equipment structure and equipment in a manner
consistent with anticipated design loads. Snubbers shall limit lateral and
vertical equipment movement at each snubber location to a maximum of
¼”(6 mm) in any direction.
C) Snubbers shall include a minimum ¼”(6 mm) thick resilient neoprene
pads to cushion any impact and to avoid any potential for metal-to-metal
contact. Maximum neoprene bearing pressure shall not exceed 1500
pounds / sq. inch (10.4 N / sq. mm). Snubber shall be capable of
withstanding an externally applied seismic force of up to 3,000 pounds
(1360 kg.) in any direction. Snubber shall be installed only after the
isolated equipment is mounted, piped, and operating so as to ensure
that no contact occurs during normal equipment operation.
D) Three-axis seismic snubbers shall be Model HS-5 as manufactured by
Kinetics Noise Control, or by other manufacturers who can meet the
requirements as listed in sections 1.04 through 1.09 inclusive, and 2.01,
2.02 and 2.03 (6)
7) Type G): Lateral 2-Axis External Seismic Snubber Assembly
A) Equipment shall be restrained against excessive lateral movement


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during a seismic event by the use of 2-axis horizontal resilient snubbers,
designed to withstand the project required seismic forces. A minimum
of two (2) snubbers are to be used at each equipment installation,
oriented to effectively restrain the isolated equipment in all horizontal
directions, and additional snubbers shall be used as required by seismic
design conditions.
B) Snubbers shall be of interlocking steel construction and shall be
consistent with anticipated design loads. Snubbers shall limit lateral
equipment movement at each snubber location to a maximum of ¼”(6
mm).
C) Snubbers shall include a minimum of ¼”(6 mm) thick resilient neoprene

pads to cushion any impact and to avoid any potential for metal-to-metal
contact. Snubber shall be installed only after the isolated equipment is
mounted, piped, and operating so as to ensure that no contact occurs
during normal equipment operation.
D) Two-axis lateral seismic snubbers shall be Model HS-2 as manufactured
by Kinetics Noise Control, or by other manufacturers who can meet the
sections 2.01, 2.02 and 2.03 (7)
8) Type H): Heavy Capacity All Direction 3-Axis External Seismic Snubber
Assembly
A) Equipment shall be restrained against excessive vertical and horizontal
movement during a seismic event by the use of 3-axis resilient
snubbers, designed to withstand the project required seismic forces. A
minimum of two (2) snubbers are to be used at each equipment
installation, oriented to effectively restrain the isolated equipment in all
three directions, and additional snubbers shall be used as required by
seismic design conditions.
B) Snubbers shall be of welded interlocking steel construction and shall be
consistent with anticipated design loads. Snubbers shall limit lateral and
vertical equipment movement at each snubber location to a maximum of
¼”(6 mm) in any direction.
C) Snubbers shall include resilient neoprene pads with a minimum
thickness of ¼”(6 mm) to cushion any impact and to avoid any potential
for metal-to-metal contact. Snubber shall be capable of withstanding an
externally applied seismic force of up to 10,000 pounds (4,540 kg.) in
any direction. Snubber shall be installed only after the isolated
equipment is mounted, piped, and operating so as to ensure that no
contact occurs during normal equipment operation.
D) Three-axis seismic snubbers shall be Model HS-7 as manufactured by


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sections 2.01, 2.02 and 2.03 (8)
9) Type I): Horizontal 1-Axis External Seismic Snubber Assembly

A) Equipment shall be restrained against excessive horizontal one-axis
movement during a seismic event by the use of single-axis resilient
snubbers, designed to withstand the project required seismic forces. A
minimum of four (4) snubbers are to be used at each equipment
installation, oriented to effectively restrain the isolated equipment in all
lateral directions.
B) Snubbers shall be of steel construction and shall be attached to the
equipment structure and equipment in a manner consistent with

anticipated design loads. Snubbers shall limit lateral equipment
movement at each snubber location in the direction of impact to a
maximum of ¼”(6 mm).
C) Snubbers shall include resilient neoprene pads with a minimum
thickness of ¼”(6 mm) to cushion any impact and to avoid any potential
for metal-to-metal contact. Snubber shall be installed only after the
isolated equipment is mounted, piped, and operating so as to eliminate
any contact during normal equipment operation.
D) Single-axis seismic snubbers shall be Model HS-1 as manufactured by
sections 2.01, 2.02 and 2.03 (9)
10) Type J): Cable Restraints For Suspended Piping and Ductwork
A) Seismic wire rope cable restraints shall consist of steel wire strand
cables, sized to resist project seismic loads, arranged to offer seismic
restraint capabilities for piping, ductwork, and suspended equipment in
all lateral directions.
B) Building and equipment attachment brackets at each end of the cable
shall be designed to permit free cable movement in all directions up to a
45 degree misalignment. Protective thimbles shall be used at sharp
connection points as required to eliminate potential for dynamic cable
wear and strand breakage.
C) Restraints shall be sized to the capacity of the cable or to the capacity of
the anchorage, whichever is the lesser.
D) Seismic wire rope connections shall be made using overlap wire rope
“U”clips or seismically rated tool-less wedge insert lock connectors.
E) Vertical suspension rods shall be braced as required to avoid potential
for buckling due to vertical ‘
up’forces. Braces shall be structural steel
angle uniquely selected to be of sufficient strength to prevent support
rod bending. Brace shall be attached to the vertical suspension rod by a
series of adjustable clips. Clips shall be capable of securely locking
brace to suspension rod without the need for hand tools.


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F) Where clevis hanger brackets are used for seismic restraint attachment,
they will be fitted with clevis internal braces to prevent buckling of the
hanger brackets.
G) Seismic cable shall be as manufactured by Kinetics Noise Control, or by
other manufacturers who can meet the requirements as listed in
sections 1.03 through 1.07 inclusive, and sections 2.01, 2.02 and 2.03
(10)
H) Seismic cable building and equipment attachment brackets shall be
Model KSCA, KSCU or KSCC as manufactured by Kinetics Noise

and 2.03 (10).
I) Seismic cable concrete anchor bolts shall be (Model KCAB Wedge) /
(Model KUAB Undercut) as manufactured by Kinetics Noise Control, or
by other manufacturers who can meet the requirements as listed in
sections 1.04 through 1.09 inclusive, and sections 2.01, 2.02 and 2.03
(10).
J) Seismic wire rope connectors shall be (Model KWRC - ‘ U’clamp) /
(Model KWGC - Tool-less wedge lock) as manufactured by Kinetics
Noise Control, or by other manufacturers who can meet the
sections 2.01, 2.02 and 2.03 (10).
K) Seismic vertical suspension stiffener rod clips shall be Model KHRC as
manufactured by Kinetics Noise Control, or by other manufacturers who
can meet the requirements as listed in sections 1.04 through 1.09
inclusive, and sections 2.01, 2.02 and 2.03 (10).
L) Clevis Internal Braces shall be Model KHHB as manufactured by
sections 2.01, 2.02 and 2.03 (10).
3.0 Execution
3.01 Installation
1) Installation of all seismic restraint materials specified in this section shall be

accomplished as per the manufacturer’ s written instructions.
2) Upon completion of installation of all seismic restraint materials and before start up
of restrained equipment, all debris shall be cleaned from beneath all protected
equipment, leaving equipment free to contact snubbers.
3) No rigid connections between the equipment and the building structure shall be
made which degrades the seismic restraint system herein specified. All electrical
conduit to restrained equipment shall be looped to allow free motion of equipment
without damage to the electrical wiring.


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4) Adjust isolators after piping systems have been filled and equipment is at operating
weight.
5) Adjust limit stops on restrained spring isolators to mount equipment at normal
operating height. After equipment installation is complete, adjust limit stops so they
are out of contact during normal operation.
6) Adjust snubbers according to manufacturer's written recommendations.
7) Adjust seismic restraints to permit free movement of equipment within normal mode
of operation.
8) Torque anchor bolts according to equipment manufacturer's written
recommendations to resist seismic forces

3.02 Execution
1) Shackle piping to the trapeze when restraining trapeze mounted piping, conduit and
ductwork. Install cables so they do not bend across sharp edges of adjacent
equipment or building structure.
2) Install steel angles to stiffen hanger rods and prevent buckling where appropriate.
Clamp with adjustable steel clamps to hanger rods. Requirements apply equally to
hanging equipment. Do not weld angles to rods
3) If there is greater than a 1/8”diameter mismatch between anchorage hardware and
hole diameter, reduce clearance in hole with epoxy grout or flanged neoprene
bushings.
4) Housekeeping Pads must be adequately reinforced and adequately thick for proper
embedment of equipment anchors. Refer also to written restraint manufacturers
instructions.
A) Install dowel rods to connect concrete base to concrete floor. Unless
otherwise indicated, install dowel rods on 18-inch (450-mm) centers
around the full perimeter of the base.
B) Install adequate reinforcement in the concrete base to ensure its
integrity in a seismic event.
C) Install wedge type anchors into concrete base. If base thickness is
inadequate for full anchor embedment, install epoxy-coated anchor bolts
that extend through concrete base and adequately anchor into structural
concrete floor.
D) Place and secure anchorage devices. Use setting drawings, templates,
diagrams, instructions, and directions furnished with items to be
embedded.
E) Install anchor bolts to elevations required for proper attachment to
supported equipment.
F) Install anchor bolts according to anchor bolt manufacturer's written
instructions.


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3.03 Inspection
1) The contractor shall notify the local representative of the seismic restraint materials
manufacturer prior to installing any seismic restraint devices. The contractor shall
seek the representative’ s guidance in any installation procedures with which he is
unfamiliar.
2) Upon completion of the installation of all seismic restraint devices herein specified,
the local representative of the seismic snubbers manufacturer shall, at the
contractors request, inspect the completed system and report in writing any
installation errors, improperly selected snubber devices, or other fault in the system
which could affect the performance of the system.

3) The installing contractor shall submit a report upon request to the building architect
and/or engineer, including the manufacturer’ s representative’ s final report,
indicating that all seismic restraint material has been properly installed, or steps to
be taken by the contractor to properly complete the seismic restraint work as per
the specifications.
4.0 Seismic Restraint for Piping and Ductwork
4.01 Piping
1) Seismically restrain all piping listed below. Use Type J Cable Restraints for all
piping supported by vibration isolation hanger assemblies, including:
A) Natural gas piping, medical gas piping, vacuum piping, petroleum based
liquid piping, and compressed air piping equal to or greater than 1”(25
mm) in inside diameter.
B) Brace remainder of piping to code requirements (IBC or TI-809-04)) or in
conformance with SMACNA (Sheet Metal and Air Conditioning
Contractors National Association, Inc.) “Seismic Restraint Manual
Guidelines for Mechanical Systems”, Second Edition (Remaining
Codes)
4.02 Ductwork
1) Seismically restrain all ductwork listed below. Use Type J Cable Restraints for all
ductwork supported by vibration isolation hanger assemblies, including:
A) All rectangular and oval ducts with cross sectional area equal to or
greater than 6 sq. ft. (0.55 sq. meters).
B) All round ducts with diameters equal to or greater than 32”(812 mm).
C) Brace remaining ductwork to code requirements (IBC or TI-809-04)) or
in conformance with SMACNA (Sheet Metal and Air Conditioning
Codes)
4.03 Conduit


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1) Seismically restrain all electrical conduit listed below. Use Type J Cable Restraints
for all conduit supported by vibration isolation hanger assemblies, including:
A) All round ducts with diameters equal to or greater than 32”(812 mm).
B) Brace all conduit to code requirements (IBC or TI-809-04) or in
conformance with SMACNA (Sheet Metal and Air Conditioning
Codes).
4.04 Fire Protection Piping

1) Fire protection, sprinkler piping, and related equipment is considered as “Life Safety
Equipment”and is to be seismically restrained per guidelines as published by NFPA
(National Fire Protection Association).
End of Section


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structure (12”) to eliminate the need for restraint.

(Refer to the building code review

KINETICS™ Seismic Design Manual

DEFINITIONS AND LOCATING REQUIREMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

KINETICS™ Seismic Design Manual

Due to variations in the installation conditions such as structural clearance, locations of

When installing restraints, lateral restraints should be installed perpendicular

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

Force Class I II III IV V VI

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Kinetics Noise Control © 2003

Lateral Restraint Examples

KINETICS™ Seismic Design Manual

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

\_/ (BOTTOM) \_/ (TOP)

KINETICS™ Seismic Design Manual

Lateral Cable Restraints Mounted to a Trapeze (Non-isolated)

\_/ (BOTTOM) \_/ (TOP)

\_/ (BOTTOM) \_/ (TOP)

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Kinetics Noise Control © 2003

Lateral Cable Restraints Mounted to a Trapeze (Isolated)

KINETICS™ Seismic Design Manual

Various Acceptable Axial Restraint Arrangements

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

V (TOP) GAUGE BRACKET

KINETICS™ Seismic Design Manual

Axial Cable Restraints (Non-isolated)

V (TOP) GAUGE BRACKET

Axial Cable Restraints (Isolated)

Hanging Systems Restrained with Struts

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

Lateral Restraint Examples

KINETICS™ Seismic Design Manual

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

Axial Restraint Examples

KINETICS™ Seismic Design Manual

Ductwork Axially Restrained with Struts

CEILING-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control © 2003

KINETICS ™ Seismic Design Manual

When installing restraints, lateral restraints should be installed perpendicular

Lateral Restraint Axial Restraint

FLOOR- OR ROOF-SUPPORTED DUCT RESTRAINT ARRANGEMENTS

Toll Free (USA only): 800-959-1229 DOCUMENT:

Kinetics Noise Control ©2003