FEMA - P-58-5 - Seismic Performance Buildings
FEMA - P-58-5 - Seismic Performance Buildings
FEMA - P-58-5 - Seismic Performance Buildings
Assessment of Buildings
Volume 5 – Expected Seismic Performance of
Code-Conforming Buildings
Prepared for
FEDERAL EMERGENCY MANAGEMENT AGENCY
Michael Mahoney, Project Officer
Robert D. Hanson, Technical Monitor
Washington, D.C.
Notice
Any opinions, findings, conclusions, or recommendations expressed in this publication do not
necessarily reflect the views of the Applied Technology Council (ATC), the Department of
Homeland Security (DHS), or the Federal Emergency Management Agency (FEMA).
Additionally, neither ATC, DHS, FEMA, nor any of their employees, makes any warranty,
expressed or implied, nor assumes any legal liability or responsibility for the accuracy,
completeness, or usefulness of any information, product, or process included in this publication.
Users of information from this publication assume all liability arising from such use.
Cover photograph – Buildings comprising the San Francisco skyline, circa 2018 (courtesy of Magnusson
Klemencic Associates/ Steve Proehl).
Foreword
PBSD is a concept that permits the design and construction of buildings with
a realistic and reliable understanding of the risk to life, occupancy, and
economic loss that may occur as a result of future earthquakes. PBSD is
based on an assessment of a building’s design to determine the probability of
experiencing different types of losses, considering the range of potential
earthquakes that may affect the structure. This allows a building owner or
regulator to select the desired performance goal for their building.
Current building codes are prescriptive in nature and are principally intended
to provide a life-safety level of protection when a design-level event, such as
an earthquake, occurs. While building codes are intended to produce
structures that meet a life-safety performance level for a specified level of
ground shaking, they do not provide designers with a means to determine if
other performance levels would be achieved. During a design level
earthquake, a code-designed building could achieve the goal of preventing
loss of life or life-threatening injury to building occupants, but could still
sustain extensive structural and nonstructural damage and be out of service
for an extended period of time. In some cases, the damage may be too costly
to repair, leaving demolition as the only option.
FEMA wishes to express its sincere gratitude to all who were involved in this
project and in the development of the FEMA P-58 Phase 2 methodology. It
is not possible to acknowledge the entire development team here. However,
In 2001, the Applied Technology Council (ATC) was awarded the first in a
series of contracts with the Federal Emergency Management Agency
(FEMA) to develop Next-Generation Performance-Based Seismic Design
Guidelines for New and Existing Buildings. These would become known as
the ATC-58 series of projects. The overall program was separated into two
major phases of work: Phase 1 – Developing a Methodology for Assessing
the Seismic Performance of Buildings; and Phase 2 – Developing
Performance-Based Seismic Design Procedures and Guidelines.
The FEMA P-58 series of products is the result of the collaborative effort of
more than 200 individuals, across all phases of work, that were involved in
the development of the underlying methodology and subsequent products and
reports. ATC is particularly indebted to the Phase 2 leadership of Ron
Hamburger (Project Technical Director), John Gillengerten (Performance
Products Team Leader), John Hooper (Products Update Team Leader), Laura
Samant (Stakeholder Products Team Leader), and the members of the Project
Management Committee, including Bill Holmes (Steering Committee Chair),
Steve Mahin, Jack Moehle, Khalid Mosalam, and Steve Winkel.
ATC would also like to thank the members of the Project Steering
Committee, the Performance Products Team, the Products Update Team, the
Stakeholder Products Team, and the many consultants who assisted these
teams as part of the Phase 2 work effort. The names of individuals who
served on these groups, along with their affiliations, are provided in the list
of Project Participants at the end of this report.
This report, one in the collection of reports comprising the FEMA P-58,
Seismic Performance Assessment of Buildings, Methodology and
Implementation, is dedicated to the memory of Stephen A. Mahin, longtime
faculty member at the University of California, Berkeley.
Foreword....................................................................................................... iii
Preface.......................................................................................................... vii
Dedication ..................................................................................................... ix
Figure 2-1 Typical plan for steel and reinforced concrete special
moment-resisting frame (SMRF) archetypes ..................... 2-6
Figure 2-3 Typical plan for special reinforced concrete shear wall
(SRCSW) archetypes ......................................................... 2-7
Figure 4-1 Design space for mid-rise, Steel SCBF, Risk Category
II archetype, showing drift levels for displacement-
controlled nonstructural component fragilities .................. 4-7
Figure C-2 Stiffness and strength input interface and design space
graphic on the User Interface tab .......................................C-4
Table 2-5 Design Space Limits for Lateral Strength and Stiffness,
Risk Category II Archetypes............................................ 2-13
Table 2-6 Design Space Limits for Lateral Strength and Stiffness,
Risk Category IV Archetypes .......................................... 2-13
Table 3-2 Design Parameters at Each Seismic Hazard Level ............ 3-2
This report is the fifth in a series of volumes comprising the FEMA P-58,
Seismic Performance Assessment of Buildings, Methodology and
Implementation (FEMA, 2012; 2018). This volume describes the work
performed to quantify the seismic performance capability of typical buildings
designed to current building code requirements, the resulting performance of
code-conforming buildings in terms of FEMA P-58 probabilistic
performance metrics, and a framework for future recommended performance
objectives based on findings from this work.
1.1 Background
In 2012, the Applied Technology Council (ATC), under contract with the
Federal Emergency Management Agency (FEMA), completed the
development of next-generation seismic performance assessment procedures.
Collectively referred to as FEMA P-58, Seismic Performance Assessment of
Buildings, Methodology and Implementation, the fundamental products in
this series included:
• FEMA P-58-1, Seismic Performance Assessment of Buildings,
Volume 1 – Methodology (FEMA, 2012a)
• FEMA P-58-2, Seismic Performance Assessment of Buildings,
Volume 2 – Implementation Guide (FEMA, 2012b)
• FEMA P-58-3, Seismic Performance Assessment of Buildings,
Volume 3 – Supporting Electronic Materials and Background
Documentation (FEMA, 2012c)
This work was the result of a series of FEMA-funded efforts to develop next-
generation performance-based seismic design guidelines for new and existing
buildings, which were initiated in 2001, and would become known as the
ATC-58 series of projects. The overall program of development was based
on the FEMA 349, Action Plan for Performance-Based Seismic Design
(FEMA, 2000), developed by the Earthquake Engineering Research Institute
(EERI), and subsequently modified and published as FEMA 445, Next-
Generation Performance-Based Seismic Design Guidelines, Program Plan
for New and Existing Buildings (FEMA, 2006). This program outlined two
major phases of work: Phase 1 – Developing a Methodology for Assessing
the Seismic Performance of Buildings; and Phase 2 – Developing
Performance-Based Seismic Design Procedures and Guidelines.
Work on Phase 1 was completed in 2012 with the publication of the initial
FEMA P-58 series of volumes. Work on Phase 2 was initiated in the same
year.
1.2 Purpose
The purpose of the Phase 2 work was to utilize the FEMA P-58 assessment
methodology developed under Phase 1 to establish recommendations for
specifying seismic performance objectives in terms of FEMA P-58
performance metrics, and to develop guidelines for effectively designing
buildings to achieve the desired performance using FEMA P-58 procedures.
This included guidance and recommendations to:
• assist decision-makers in selecting appropriate performance objectives
for buildings of different occupancies;
• assist structural engineers in identifying appropriate structural and
nonstructural design strategies to achieve specific performance
objectives; and
• assist structural engineers in efficiently developing preliminary designs
with minimal iteration during the design process.
Work conducted under Phase 2 has updated and expanded the FEMA P-58,
Seismic Performance of Buildings, Methodology and Implementation series
of volumes to include the following:
• FEMA P-58-1, Seismic Performance Assessment of Buildings,
Volume 1 – Methodology, Second Edition (FEMA, 2018a)
• FEMA P-58-2, Seismic Performance Assessment of Buildings,
Volume 2 – Implementation Guide, Second Edition (FEMA, 2018b)
• FEMA P-58-3, Seismic Performance Assessment of Buildings,
Volume 3 – Supporting Electronic Materials and Background
Documentation, Third Edition (FEMA, 2018c)
• FEMA P-58-4, Seismic Performance Assessment of Buildings,
Volume 4 – Methodology for Assessing Environmental Impacts
(FEMA, 2018d)
• FEMA P-58-5, Seismic Performance Assessment of Buildings,
Volume 5 – Expected Seismic Performance of Code-Conforming
Buildings (FEMA, 2018e)
• FEMA P-58-6, Guidelines for Performance-Based Seismic Design of
Buildings (FEMA, 2018f)
• FEMA P-58-7, Building the Performance You Need, A Guide to State-of-
the-Art Tools for Seismic Design and Assessment (FEMA, 2018g)
Beyond safety objectives, the SEAOC Blue Book acknowledged that some
seismic design requirements were also intended to minimize property
damage and preserve functionality in cases such as essential, or otherwise
important structures. In the National Earthquake Hazards Reduction
Program (NEHRP) Recommended Provisions for the Development of Seismic
Regulations for New Buildings (FEMA, 1988), the stated performance intent
of the Provisions was to “minimize hazard to life for all buildings,” “increase
the expected performance of higher occupancy structures,” and “improve the
capability of essential facilities to function during and after an earthquake.”
This remained the basic underlying philosophy of the Provisions until the
2009 Edition (FEMA, 2009a), when the performance statement was revised
to also include consideration of minimizing structural and nonstructural
repair costs “where practical to do so.”
References and a list of project participants are provided at the end of this
report.
2.1 Overview
Some aspects, such as Risk Category and Seismic Design Category are
dictated by the building code, and other aspects, such as site characterization
and seismic hazard level, are completely outside the control of the structural
engineer. Each building project, however, is unique and in some cases the
structural engineer may have more or less influence over a particular design
consideration.
Table 2-2 shows design considerations that were parametrically varied in the
archetype designs. Design considerations that were anticipated to have a
high impact on performance were primary factors considered in this study,
Figure 2-2 Typical plan for steel buckling-restrained braced frame (BRBF)
and special concentrically braced frame (SCBF) archetypes.
Building occupancy determines the type and quantity of contents, and the
number of people that will be present (and when), within a building.
Building occupancy, along with risk and importance, influences the seismic
design force level. Risk Categories are a categorization of buildings based
on use (or occupancy) and the risk associated with unacceptable
performance. Risk Categories are used to reduce permissible story drifts,
trigger increased construction quality assurance requirements, and assign
importance factors that increase seismic design loading. Buildings and other
structures that represent a low risk to human life are assigned Risk
Category I; standard occupancy structures are assigned Risk Category II;
hazardous or otherwise important facilities are assigned Risk Category III;
and essential facilities are assigned Risk Category IV.
Office and healthcare occupancies also differ in the types and quantities of
nonstructural components and systems assumed to be present in the building.
In addition to architectural, mechanical, electrical, and plumbing components
in office archetypes, healthcare archetypes are populated with representative
fixed and mobile medical equipment typically found in acute care hospitals.
All structures must conform to the minimum strength, stiffness, and seismic
detailing requirements of the building code. In theory, all buildings could be
designed to just meet the minimum base shear strength and maximum
allowable drift limits specified for the selected system, configuration, height,
and Risk Category. In practice, however, most structures exceed code
minimums in one way or another, and for a variety of reasons.
Because designs that exceed code minimums are not controlled by code
requirements, the possible range of designs is theoretically infinite. To
determine a set of reasonable bounds on strength and stiffness, a workshop
was convened to gain insight from practicing structural engineers on typical
characteristics associated with code-conforming seismic force-resisting
systems. In this workshop, engineers from multiple design firms, in diverse
areas of seismic design practice, were asked to provide guidance on the
probable range of strength and stiffness, relative to code-specified
minimums, that code-conforming buildings might have, given other factors.
A typical design space is shown in Figure 2-5, which illustrates typical upper
and lower bound assumptions for strength and stiffness. Lateral stiffness, in
terms of story drift ratio, is presented on the horizontal axis, and lateral
strength, as a multiple of the minimum design base shear strength, is
presented on the vertical axis. Thirteen points are used to characterize
archetypes with different strength and stiffness combinations throughout the
design space.
The four corners of the design space represent the limits of the combinations
of lateral strength and stiffness considered in the study. Point 1 represents a
structure with a low design story drift ratio and the minimum permitted
lateral strength. Point 2 represents the theoretical code-minimum design,
which is a structure having the maximum practical design story drift ratio
and the code-minimum lateral strength. Point 3 represents the stiffest,
strongest structure considered in the study. Point 4 represents a flexible
structure having the maximum practical design story drift ratio and a high
level of lateral strength. Different systems have different upper and lower
bound assumptions for strength and stiffness. Limits for the design space of
each system are summarized in Table 2-5 and Table 2-6.
Table 2-6 Design Space Limits for Lateral Strength and Stiffness, Risk
Category IV Archetypes
Maximum
Strength Code
(Multiple of Maximum
Code Minimum Maximum Allowable
Seismic Force-Resisting Design Drift Ratio Drift Ratio Drift Ratio
System Base Shear) (%) (%) (%)
Low-Rise Archetypes
Steel SMRF 3.0 1% 1.5% 1.5%
RC SMRF 2.0 1% 1.5% 1.5%
Steel BRBF 2.0 0.5% 1.5% 1.5%
Steel SCBF 2.0 0.25% 1% 1.5%
Special RCSW 3.0 0.25% 1% 1.5%
Mid-Rise Archetypes (1)
The parametric variation of strength and stiffness within the design space
includes combinations of lateral strength and stiffness that might not be
realistic for some systems. However, all points within the boundaries of the
design space are considered necessary to characterize the performance of the
range of parameters considered to be code-conforming for each system.
The generic design space in Figure 2-6, however, is not representative of any
one design space. It is intended to illustrate the relative differences between
representative designs across all systems. The actual dimensions of the
design space and the properties associated with representative designs are
calculated uniquely for each system and summarized in Tables 2-7 and 2-8.
A comparison between actual design space limits and representative design
points for mid-rise, Risk Category II, steel special moment-resisting frame
and buckling-restrained braced frame systems is shown in Figure 2-7.
Table 2-8 Lateral Strength and Drift Ratios for Representative Designs,
Risk Category IV Archetypes
Seismic Force-Resisting Strength (Multiple of Code Drift Ratio
System Minimum Design Base Shear) (%)
Low-Rise Archetypes
Steel SMRF 2.0 1.4%
RC SMRF 1.5 1.4%
Steel BRBF 1.5 1.17%
Steel SCBF 1.125 0.63%
Special RCSW 2.0 0.44%
Mid-Rise Archetypes(1)
Steel SMRF 2.0 0.9%
RC SMRF 1.5 0.9%
Steel BRBF 1.5 0.83%
Steel SCBF 1.125 0.63%
Special RCSW 2.0 0.44%
Notes: (1)
Risk Category IV archetypes do not have high-rise variants.
Archetypes are defined by lateral system type, height, lateral strength, lateral
stiffness, occupancy, and design ground motion. Archetypes were designed
for five different seismic force-resisting systems, two Risk Categories, and
three levels of seismic hazard. Table 2-9 summarizes the combinations of
Steel SMRF II ■ ■ ■
(195 archetypes) IV ■ ■
RC SMRF II ■ ■ ■
(195 archetypes) IV ■ ■
Steel SCBF II ■ ■ ■
(195 archetypes) IV ■ ■
Special RCSW II ■ ■ ■
(195 archetypes) IV ■ ■
Steel SMRF II ■ ■
(156 archetypes) IV ■ ■
RC SMRF II ■ ■
(156 archetypes) IV ■ ■
Steel SCBF II ■ ■
(156 archetypes) IV ■ ■
Special RCSW II ■ ■
(156 archetypes) IV ■ ■
For each archetype, a PACT building performance model was created that
includes project information, building information, population data,
component structural and nonstructural fragilities, performance groups,
collapse fragilities, structural analysis results (drift, acceleration, and
velocity), residual drift information, and hazard curves. Assembly of the
building performance models is described in Chapter 4.
2.6 Limitations
Systems were selected from those identified in Table 3-1, along with the
response modification coefficient, R, the system overstrength factor, Ω0, and
deflection amplification factor, Cd, from ASCE/SEI 7-10, Table 12.2-1.
RC SMRF 8 3 5.5
Steel SCBF 6 2 5
The site seismic hazard level was selected from Table 3-2, which summarizes
the short-period, SDS, and 1-second period, SD1, design values at each level.
RC SMRF 2.0
Dynamic properties for each archetype were determined based on the design
story drift at the point of interest in the design space, using an approximate
procedure for estimating mode shape and Rayleigh’s method for estimating
period.
First mode shapes, ϕj1, for each archetype were estimated using an
approximate method presented in Miranda and Taghavi (2005). In this
procedure, buildings are modeled as an equivalent continuum structure
consisting of a flexural cantilever beam and shear cantilever beam pin-
connected by axially rigid links. Estimated mode shapes are functions of the
total height of the building and structural stiffness parameters α and δ, which
control the response of the structure. Value of α represent variations in the
behavior of the structure from a pure flexural response (α = 0), to a pure
Given the seismic force-resisting system, building height, and hazard level,
the bare-frame fundamental period, T1,BF, was calculated such that the
maximum story drift is equal to the design drift at the point of interest in the
design space. Story drift profiles were developed using code lateral forces
and the target drift ratio, and the bare-frame fundamental period
corresponding to the design drift was determined using Rayleigh’s method in
an iterative procedure.
To obtain lateral deflections, δx, the first mode shape was computed using
Miranda and Taghavi (2005). The amplitudes of the fundamental mode
Because the magnitude of the forces, fx, used in the Rayleigh method are a
function of period, an initial estimate of period is needed. For the first
iteration, the code upper limit on period, Tmax, was used:
Tmax = CuTa
∑w h
i =1
i i
k
where V is the seismic base shear, wi and wx are the portions of the total
effective seismic weight of the structure (W) located or assigned to level i or
x, and hi and hx is the height (in feet) from the base to level i or x. Because
the mass distribution of the building is assumed to be uniform, wx = wi =
W/N, where N is the number of stories. Coefficient, k, is a number that
defines the shape of the equivalent lateral force pattern, and depends on the
period of the structure. For structures with a period of 0.5 s or less, k = 1; for
structures with a period of 2.5 s or more, k = 2; and for structures with a
The seismic design base shear V was calculated using ASCE/SEI 7-10,
Equation 12.8-1:
V = CsW
The value of Cs need not exceed the limits given by ASCE/SEI 7-10,
Equation 12.8-3 and Equation 12.8-4:
S D1
CS = for T ≤ TL
T ( R Ie )
S D1TL
CS = for T > TL
T ( R Ie )
2
If S1 is greater than or equal to 0.6g, then Cs shall not be less than the limit
given by ASCE/SEI 7-10, Equation 12.8-6:
S1
CS = 0.5
R Ie
Forces, fx, were then used to calculate a new estimate of period, Tcomputed. The
fundamental circular frequency and the corresponding period using
Rayleigh’s method are:
n
g ∑δ x f x
ωcomputed = n
x =1
∑δ
x =1
2
x wx
2π
Tcomputed =
ωcomputed
where values of the modification factor, MF, for different systems are
summarized in Table 3-6. Period modification factors, MF, are based on
comparisons between computed and measured fundamental periods in
instrumented buildings described in Harris, et al., 2016 (FEMA P-58/BD-
3.7.17 Report).
RC SMRF 0.85
The code minimum base shear strength, Vb, was computed based on
ASCE/SEI 7-10, Equation 12.8-1:
Vb = CsW
ASCE/SEI 7-10 places an upper limit on the building period used to calculate
the design base shear strength. The upper limit period, Tmax, is:
Tmax = CuTa
The first mode spectral acceleration, Sa(T1), was determined based on the
provisions of ASCE/SEI 7-10, Section 11.4.5, using one of the following
equations:
T
S a (T1 ) S DS 0.4 + 0.6 1
= for T1 < T0
T0
S D1
S a (T1 ) = for Ts < T1 < TL
T1
where Sa(T1) is the 5 percent damped spectral acceleration at the lesser of the
effective fundamental period, T1,EFF, and Tmax; SDS is the design spectral
response acceleration parameter in the short period range; SD1 is the design
spectral response acceleration parameter at a period of 1.0 sec; and:
S D1
T0 = 0.2
T1
S D1
TS =
S DS
TL = Long-period transition period
None of the archetypes had periods greater than the long-period transition
period, TL. Because a cap is placed on the fundamental period of a building
for strength checks, the design base shear for lateral strength can be larger
The yield strength, Vy, of a structure can be estimated using plastic analysis
concepts, nonlinear analysis in accordance with ASCE/SEI 41-13, Seismic
Evaluation and Retrofit of Existing Buildings (ASCE, 2017c), or a
combination of the response modification coefficient, R, and the systems
overstrength factor, Ω0, specified in ASCE/SEI 7-10. In this study, the yield
strength was taken as 1.5 times the code minimum base shear strength of the
archetype.
Upper-bound values for the design space overstrength factor, OF, expressed
as a multiple of the code minimum base shear strength, are provided in Table
3-3. For the purpose of determining yield strength, values of OF for
intermediate points in the design space are determined by linear
interpolation.
Yield drift ratios for each system were based on parametric and sensitivity
studies using approximate methods of analysis, as follows:
• An approximate method of analysis (e.g., portal method for frames) was
selected to derive formulas for yield drift in different structural systems.
• Parameters that significantly influence yield drift (e.g., yield strain, ratio
of bay span to story height, ratio of column depth to girder depth, ratio of
yield stress in columns to yield stress in beams, and aspect ratio of walls)
were identified.
• Ranges of probable yield drift were determined by parametric variation
of parameters identified as significant.
An estimate of the yield drift of steel SMRF archetypes was derived using
the portal method of analysis:
εy h L
=∆y α +
3 d c db
where εy is the yield strain of the steel, h is the story height, L is the bay span,
db is the beam depth, dc is the column depth, and 𝛼𝛼 is the ratio of the stress in
the column to the yield stress in the beam.
To select the yield drift ratio, the yield stress of the steel was varied from 50
ksi to 55 ksi, the bay span to story height ratio (L/h) was varied from 1 to 2,
the column depth to beam depth ratio (dc/db) was varied from 0.5 to 0.75, and
the ratio of the stress in the column to the yield stress in the beam was varied
from 0.7 to 0.8, resulting in a yield drift estimate in the range from 0.8
percent to 1.3 percent. Sensitivity studies showed negligible change in losses
with changes in the assumed yield drift ratio. As a result, a yield drift ratio
of 1 percent was used for steel SMRF archetypes across the entire design
space.
An estimate of the yield drift of RC SMRF archetypes was derived using the
portal method of analysis:
εy h L
=∆y α +
6 d c − kd c db − kdb
where εy is the yield strain of the steel, h is the story height, L is the bay span,
db is the beam depth, dc is the column depth, α is the ratio of the stress of the
column steel to the yield stress in the beam steel, kdc is the depth of the
neutral axis of the column, and kdb is the depth of the neutral axis of the
beam at yield. The depth of the neutral axis at yield was calculated as:
kd d
= ( ( nρ )
2
+ 2n ρ − n ρ )
where n is the modular ratio n = (Es/Ec) and ρ is the ratio of longitudinal
reinforcement in the element.
where εy is the yield strain of the steel, h is the story height, and L is the bay
span.
To select the yield drift ratio, the yield stress of the steel was varied from 38
ksi to 46 ksi, and the bay span to story height ratio (L/h) was varied from
1.15 to 2.4 to account for possible brace angles between 40 degrees and 60
degrees. The resulting yield drift estimates varied from 0.26 percent to 0.37
percent. A yield drift ratio of 0.30 percent was used for all steel BRBF
archetypes across the entire design space.
where εy is the yield strain of the steel, h is the story height, and L is the bay
span.
To select the yield drift ratio, the yield stress of the steel was varied from 50
ksi to 55 ksi and bay span to story height ratio (L/h) was varied from 1.15 to
2.4 to account for possible brace angles between 40 degrees and 60 degrees.
where ϕ1,i is the value of the fundamental mode shape of the building
(normalized to 1 at the roof level) at the ith floor level. Story drifts were
calculated from the floor displacements at each story, and the maximum
story drift was taken as the yield drift of the archetype. As a result, a yield
drift ratio of 0.5 percent was selected for all 2-story RCSW archetypes, 0.26
percent was selected for all 5-story RCSW archetypes, and 0.63 percent was
selected for all 12-story RCSW archetypes, across the entire design space.
Median collapse capacities were inferred from the code minimum base shear
strength for each archetype. Using the code minimum base shear strength,
the effective value of the design spectral acceleration at the fundamental
period, SaD, at which the structure satisfies all applicable seismic design
criteria of ASCE/SEI 7-10, was determined using FEMA P-58, Volume 1,
Equation 6-2:
V
S aD = R
W
For all collapse fragilities, a single partial collapse mode was considered,
assuming 30 percent of the floor area collapses. Within the collapsed area,
30 percent of the building population was assumed to be fatalities, and 70
percent was assumed to sustain serious injuries. As regular, well-configured
structures, a dispersion, β, of 0.6 was assumed across all archetypes.
Structural properties at each point in the design space are unique and are
different for each of the 1,755 combinations of system, risk category, hazard
level, building height, and design space point. Because representative
designs are combinations of lateral strength and stiffness judged to be most
typical for each seismic force-resisting system, properties of representative
designs are reported to provide a sense of the structural properties for each
system, and the variation between systems.
Representative designs are not necessarily one of the 13 points in the design
space, and are generally taken as the average of three or four points. Tables
3-7 to 3-11 summarize the range of key structural parameters calculated at
representative design points for SDC D archetypes in each system.
Table 3-7 Range of Structural Properties for Representative Design Points, Steel SMRF Archetypes,
SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 1.25 - 1.45 1.06 - 1.23 0.73 0.021 - 0.025 1.0 0.10 3.7 - 6.1
Low-Rise
IV 0.83 - 0.90 0.70 - 0.76 0.73 0.014 - 0.015 1.0 0.15 - 0.16 5.8 - 9.6
II 1.52 - 1.72 1.29 - 1.46 1.11 0.018 - 0.02 1.0 0.07 2.4 - 4.1
Mid-Rise
IV 0.79 - 0.90 0.67 - 0.77 1.11 0.009 - 0.01 1.0 0.15 - 0.17 6.0 - 10.0
II 2.46 - 2.63 2.09 - 2.24 2.23 0.018 - 0.02 1.0 0.03 - 0.04 1.3 - 2.2
High-Rise
IV - - - - - - -
Table 3-8 Range of Structural Properties for Representative Design Points, RC SMRF Archetypes,
SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 1.25 - 1.45 0.69 - 0.80 0.61 0.021 - 0.025 0.55 0.12 4.0 - 5.2
Low-Rise
IV 0.83 - 0.90 0.45 - 0.49 0.61 0.014 - 0.015 0.55 0.19 6.0 - 7.9
II 1.52 - 1.72 0.83 - 0.94 0.96 0.018 - 0.02 0.55 0.09 - 0.09 2.9 - 3.8
Mid-Rise
IV 0.79 - 0.90 0.44 - 0.50 0.96 0.009 - 0.01 0.55 0.19 6.0 - 7.9
II 2.46 - 2.63 1.35 - 1.45 2.11 0.018 - 0.02 0.55 0.05 - 0.06 1.8 - 2.3
High-Rise
IV - - - - - - -
Table 3-10 Range of Structural Properties for Representative Design Points, Steel SCBF Archetypes,
SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 0.37 - 0.53 0.32 - 0.45 0.32 0.005 - 0.01 0.35 0.17 4.0
Low-Rise
IV 0.35 - 0.48 0.30 - 0.41 0.32 0.004 - 0.008 0.35 0.25 6.0
II 0.47 - 0.73 0.40 - 0.62 0.64 0.005 - 0.01 0.35 0.16 - 0.17 3.9 - 4.0
Mid-Rise
IV 0.44 - 0.60 0.38 - 0.51 0.64 0.004 - 0.008 0.35 0.25 6.0
II 1.21 - 2.05 1.03 - 1.75 1.24 0.009 - 0.016 0.35 0.08 -0.10 1.94 - 2.34
High-Rise
IV - - - - - - -
Table 3-11 Range of Structural Properties for Representative Design Points, Special RCSW Archetypes,
SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 0.21 - 0.33 0.19 - 0.30 0.32 0.003 - 0.006 0.5 0.20 4.5 - 7.5
Low-Rise
IV 0.21 - 0.33 0.19 - 0.30 0.32 0.003 - 0.006 0.5 0.30 6.8 - 11.3
II 0.29 - 0.47 0.26 - 0.42 0.64 0.003 - 0.006 0.26 0.20 4.5 - 7.5
Mid-Rise
IV 0.29 - 0.47 0.26 - 0.42 0.64 0.003 - 0.006 0.26 0.30 6.8 - 11.3
II 1.02 - 1.41 0.92 - 1.27 1.24 0.009 - 0.013 0.63 0.10 - 0.13 2.9 - 4.9
High-Rise
IV - - - - - - -
In the simplified design approach, design story drift ratios are determined by
the point of interest in the design space, and the resulting stiffness, and base
shear are back-calculated using code-based strength and period equations.
Although design story drift ratios are the same at each hazard level, the
designs vary between hazard levels due to differences in design spectra and
the resulting spectral response acceleration parameters SDS and SD1. Because
the required design forces change with hazard, the resulting periods (i.e.,
stiffnesses) must change accordingly to match the specified drift ratios at
different force levels. As a result, properties for Low SDC D archetypes are
weaker and more flexible than SDC D archetypes, and properties for SDC
E/F archetypes are stronger and stiffer than all other archetypes.
Median estimates of story drift ratio, ∆i* , floor acceleration, ai* , and floor
velocity, vi* , were computed using the simplified analysis procedure as
follows:
• The pseudo lateral force, V, was calculated and distributed over the
height of the archetype.
Figure 3-1 Definition of floor levels, story numbers, and floor heights
used in the simplified analysis procedure (FEMA P-58,
Volume 1).
where a is a function of the soil site class (for site class D, a = 60), and S is
the strength ratio given by FEMA P-58, Volume 1, Equation 5-6:
S a (T1 )W
S=
Vy1
where Vy1 is yield strength of the building in first mode response estimated in
Section 3.5, and W is the total seismic weight. If the value of the strength
ratio, S, is less or equal to 1.0, then C1 is taken as 1.0.
When the value of S is less or equal to 1.0, C2 is also taken as 1.0. When S is
greater than 1.0, C2 is computed as:
( S − 1)
2
( S − 1)
2
The first mode effective weight, W1, was calculated from FEMA P-58,
Volume 1, Equation 5-4:
∑ w jφ j12
j =2
where wj is the lumped weight at floor level j, and N is the number of floors
in the building above the base.
where ϕj1, is the jth ordinate of the first mode shape (determined using the
simplified structural analysis procedures in Section 3.3), Г1 is the modal
participation factor, 𝜔𝜔 is the first circular frequency of vibration, and g is the
gravitational constant.
For uniform weight over the building height, the modal participation factor,
Г1, is:
N +1
W1 W1 j =2
∑φ j1
Γ=
1 =
N +1
Lh1 W N +1
∑ N
=j 2=j 2
φ j1 ∑ φ j12
Because W1 may not be taken as less than 80 percent of the effective seismic
weight, the modal participation factor Г1 cannot be less than:
0.8W 0.8N
Γ=
1,min = N +1
Lh1
∑φ
j =2
j1
where Dj and Dj+1 are lateral displacements of the floor levels immediately
above and below the story and hi is the story height of story i.
Story drift ratios were corrected to account for inelastic behavior and higher
mode effects. Estimates of median story drift ratio, ∆*i , for each story i, were
calculated using FEMA P-58, Volume 1, Equation 5-10:
=∆*i H ∆i ( S , T1 , hi , H ) × ∆ i
The values of the coefficients a0 through a5 were obtained from FEMA P-58,
Volume 1, Table 3-7 and Table 3-8, and Saldana and Terzic, 2018 (FEMA
P-58/BD-3.7.21 Report); S is the strength ratio; T1 is the effective
fundamental period including period stiffening effects; and H is the total
building height above the base, as defined in Figure 3-1. If the response is
elastic, HΔi = 1.
At the base of the building, peak floor acceleration is equal to the peak
ground acceleration. At other floor levels, i, the estimated median peak floor
acceleration, ai* , relative to a fixed point in space, was derived from the peak
ground acceleration using FEMA P-58, Volume 1, Equation 5-12:
=ai* Hai ( S , T , hi , H ) × PGA
The values of the coefficients a0 through a5 were obtained from FEMA P-58,
Volume 1, Table 3-7 and Table 3-8, and Saldana and Terzic, 2018 (FEMA
P-58/BD-3.7.21 Report). If the response is elastic, S was taken as 1.0.
At the base of the building, peak floor velocity is equal to the peak ground
velocity, PGV, estimated by dividing the spectral velocity at a period of one
second, Sv(1.0 s), by a factor of 1.65 (Newmark and Hall, 1982; Huang and
Whittaker, 2012).
At other floor levels, i, the estimated median peak floor velocity, vi* , relative
to a fixed point in space, was computed from the peak ground velocity and
reference floor velocity, vsi, using FEMA P-58, Volume 1, Equation 5-16:
=vi* Hvi ( S , T , hi , H ) × vsi
The values of the coefficients a0 through a5 were obtained from FEMA P-58,
Volume 1, Table 3-7 and Table 3-8, and Saldana and Terzic, 2018 (FEMA
P-58/BD-3.7.21 Report). The reference floor velocity, vsi, was determined
from FEMA P-58, Volume 1, Equation 5-18:
T1 Vy1 δ
vsi PGV + 0.3
= ( Γ 1) i
2π W1 / g δr
Structural demands vary at each level in each of the 1,755 archetypes, and
are different for each of the five intensity levels between 20% and 100%
MCE. Because it is not possible to present the entire set of demand vectors
for each archetype, values for representative designs are reported to provide a
sense of the structural demands for each system, and the variation between
systems. Tables 3-13 to 3-17 summarize the range of median drifts,
accelerations, and velocities for representative design points for each system.
Table 3-13 Range of Median Structural Demands for Representative Design Points,
Steel SMRF Archetypes, SDC D, Design Earthquake Level
Story Drift Residual Drift Peak Floor Peak Floor
Risk Ratio, Ratio, Acceleration, Velocity,
Height Category % % g in/sec
II 1.49 - 2.68 0.15 - 0.50 0.47 - 0.52 22.3 - 34.1
Low-Rise
IV 1.03 - 1.73 0.01 - 0.22 0.52 - 0.57 22.8 - 35.4
II 1.09 - 1.85 0.03 - 0.26 0.42 - 0.48 21.5 - 32.7
Mid-Rise
IV 0.60 - 1.03 0.00 - 0.01 0.52 - 0.58 22.5 - 36.7
II 0.36 - 1.34 0.00 - 0.11 0.30 - 0.41 21.0 - 33.0
High-Rise
IV - - - -
Table 3-14 Range of Median Structural Demands for Representative Design Points,
RC SMRF Archetypes, SDC D, Design Earthquake Level
Story Drift Residual Drift Peak Floor Peak Floor
Risk Ratio, Ratio, Acceleration, Velocity,
Height Category % % g in/sec
II 1.04 - 1.83 0.15 - 0.38 0.46 - 0.52 22.7 - 30.9
Low-Rise
IV 0.54 - 1.00 0.00 - 0.14 0.53 - 0.58 22.7 - 30.7
II 0.75 - 1.26 0.06 - 0.21 0.43 - 0.49 22.8 - 30.7
Mid-Rise
IV 0.31 - 0.60 0.00 - 0.01 0.53 - 0.59 22.7 - 31.2
II 0.23 - 0.84 0.00 - 0.09 0.35 - 0.56 22.7 - 32.4
High-Rise
IV - - - -
Table 3-16 Range of Median Structural Demands for Representative Design Points,
Steel SCBF Archetypes, SDC D, Design Earthquake Level
Story Drift Residual Drift Peak Floor Peak Floor
Risk Ratio, Ratio, Acceleration, Velocity,
Height Category % % g in/sec
II 0.51 - 1.13 0.05 - 0.23 0.99 - 1.48 19.1 - 21.4
Low-Rise
IV 0.39 - 0.88 0.01 - 0.16 1.06 - 1.56 21.7 - 24.0
II 0.25 - 0.88 0.00 - 0.16 0.84 - 1.42 20.7 - 24.9
Mid-Rise
IV 0.21 - 0.62 0.00 - 0.08 0.93 - 1.50 23.3 - 27.8
II 0.17 - 1.43 0.00 - 0.38 0.60 - 0.93 35.0 - 125.5
High-Rise
IV - - - -
Table 3-17 Range of Median Structural Demands for Representative Design Points,
Special RCSW Archetypes, SDC D, Design Earthquake Level
Story Drift Residual Drift Peak Floor Peak Floor
Risk Ratio, Ratio, Acceleration, Velocity,
Height Category % % g in/sec
II 0.11 - 0.35 0.00 - 0.00 0.63 - 0.91 21.2 - 26.8
Low-Rise
IV 0.09 - 0.23 0.00 - 0.00 0.37 - 0.93 21.1 - 30.0
II 0.08 - 0.35 0.00 - 0.03 0.59 - 0.90 21.5 - 31.8
Mid-Rise
IV 0.07 - 0.34 0.00 - 0.02 0.63 - 0.92 21.3 - 38.5
II 0.11 - 0.72 0.00 - 0.03 0.42 - 0.99 22.7 - 46.0
High-Rise
IV - - - -
Demands are shown for the SDC D hazard level, at the design earthquake
intensity level, and represent the maximum and minimum values over the
height of multi-story archetypes. Drift, acceleration, and velocity demands at
other hazard levels, and at different intensity levels, are necessarily different,
and not shown here.
Data in the project information section includes the project ID and building
description, regional and date cost multipliers, and the solver random seed
value. Each archetype was assigned the same regional and date cost
multipliers, and the same solver random seed value.
PACT default values for the regional cost and date multipliers were not
adjusted. The results of the performance evaluation are, therefore, based on
repair cost consequence functions for the Northern California region, dated
2011. Because reported repair costs are expressed as a percentage of
replacement cost, the assessment results are generally applicable to any
timeframe.
The solver random seed value is a whole number used to initiate all
sequences of random number generation utilized in the performance
assessment. Setting the value of the random seed to zero will cause PACT to
randomly seed each generation sequence. If a different solver random seed
number is used for multiple runs of a performance model, the results of each
performance assessment will be different, even if there are no changes to the
The replacement cost used for each occupancy and Risk Category is shown
in Table 4-1. The replacement time for all archetypes was set equal to 720
days.
The total loss threshold is the ratio of repair cost to replacement cost that
triggers the decision on whether a building is a total loss. When the total loss
threshold is set to a value less than 1.0, PACT will report that a building is a
total loss in any realization that the loss threshold is exceeded, and damage
data for individual components will not be available. In this study, the total
loss threshold was set equal to 1.0 to avoid truncation of performance data
obtained from the assessments. In practice, building owners may elect to
replace rather than repair a damaged building when repair costs are more
than about 50 percent of the replacement value of the building (i.e., a total
loss threshold of 0.5).
Height factors are applied to each floor and reflect increased repair costs
associated with repair of damage in the upper levels of taller structures.
These factors were set in accordance with suggested values in FEMA P-58,
Volume 2, Table 2-1.
The equivalent continuous occupancy (ECO) population model was used for
all archetypes, and the same population models were assigned to all floors of
a given archetype. The ECO population is a time-weighted average
population theoretically occupying a building on a continual basis. It
represents the number of persons present, on average, throughout the year,
considering all times of day and days of the week, and is expressed as the
number of occupants per 1,000 square feet. Values for equivalent continuous
occupancy for office and healthcare occupancies were calculated based on
information provided in Seligson, 2008 (FEMA P-58/BD-3.7.8 Report). The
default equivalent continuous occupancy (ECO) for office occupancies is
0.944 persons per 1000 sq. ft., and for healthcare occupancies is 3.238
persons per 1000 sq. ft.
Where possible, the quantity of each structural component is the same for all
building performance models in a single design space. If needed, component
sizes were varied within the same family of fragilities to keep the structural
layout the same.
Figure 4-1 shows the design space for a typical mid-rise, steel special
concentric braced frame, Risk Category II archetype. For this archetype,
displacement-controlled component fragilities were proportioned to
accommodate five different design story drift levels: the maximum design
story drift ratio, 0.0125, at points 2, 4, and 13; 0.01 at points 6 and 8; 0.0075
at points 9, 10, and 11; 0.005 at points 5 and 7; and the minimum design
story drift ratio, 0.0025, at points 1, 3, and 12. Displacement-controlled
component fragilities in other archetypes were similarly determined.
Figure 4-1 Design space for mid-rise, Steel SCBF, Risk Category II archetype,
showing drift levels for displacement-controlled nonstructural
component fragilities.
For curtain wall systems that span from floor to floor, Dp is equal to the drift
limit at the point of interest in the design space, Δlimit, and:
Δfallout ≥ 1.25IeΔlimit
A total of 23 different curtain wall drift demands were identified across all
archetype variants. For each point in the design space a curtain wall fragility
was selected from the PACT fragility database such that the median capacity
associated with Δfallout exceeds the drift demand, 1.25IeΔlimit. Selected curtain
wall fragilities, and the associated drift demands, are shown in Table 4-7.
Table 4-7 includes nine curtain wall fragilities that meet or exceed drift
demand requirements. Fragility B2022.032 is a dry-glazed system without
any clearance between the glass and the frame. This fragility represents a
curtain wall that is suitable for installation in buildings with low story drift
demands, and was used where drift demands are less than 0.011. Fragilities
for higher drift demands include an allowance for clearance between the
glass and the frame. To maintain reasonably close correlation (i.e., to avoid
significant over-conservatism) between the design drift demand and the drift
where θi is the median capacity for damage state i, and θiN is the median
capacity for damage state i for an identical stair without a seismic joint. The
dispersion β was taken as 0.50 for all damage states.
The code-based limit state procedures of FEMA P-58, Volume 1, Section 3.8
were used to calculate the median capacity of acceleration controlled
nonstructural components. The median capacity is given by FEMA P-58,
Volume 1, Equation 3-2:
θbrittle = Cq e(2.81β )φ Rn
The design resistance, ϕRn, is taken as the ratio of Fp/Wp, where Wp is the
component operating weight, and Fp is the horizontal design force calculated
using ASCE/SEI 7-10 Section 13.3.1, considering upper and lower limits on
the component design force in ASCE/SEI 7-10 Equations 13.3-2 and 13.3-3.
Tables 4-8 through 4-10 provide values of Fp/Wp based on the short-period
acceleration parameter, SDS, component response modification factor Rp, and
the height of the component in the structure expressed in terms of x/h, where
x is the height of the point of attachment of the component, and h is the
height of the structure. Values in the tables identified with an asterisk
indicate cases in which the ASCE/SEI 7-10 lower limit (Equation 13.3-3)
governed.
Table 4-8 Ratio of Fp/Wp for Acceleration-Controlled Components in Low SDC D, Risk
Category II Archetypes
x/h
Rp 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
1.5 0.15* 0.16 0.19 0.21 0.24 0.27 0.29 0.32 0.35 0.37 0.40
2 0.15* 0.15* 0.15* 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30
2.5 0.15* 0.15* 0.15* 0.15* 0.15* 0.16 0.18 0.19 0.21 0.22 0.24
3.5 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15 0.16 0.17
4.5 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15*
6 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15* 0.15*
Table 4-9 Ratio of Fp/Wp for Acceleration-Controlled Components in SDC D, Risk Category II
Archetypes
x/h
Rp 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
1.5 0.30* 0.32 0.37 0.43 0.48 0.53 0.49 0.64 0.69 0.75 0.80
2 0.30* 0.30* 0.30* 0.32 0.36 0.40 0.44 0.48 0.52 0.56 0.60
2.5 0.30* 0.30* 0.30* 0.30* 0.30* 0.32 0.35 0.38 0.42 0.45 0.48
3.5 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30 0.32 0.34
4.5 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30*
6 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30* 0.30*
Values in the tables are for Risk Category II archetypes (Ie or Ip, equal to
1.0). Values for Risk Category IV archetypes are directly proportional to the
change in importance factor.
Assumed repair and replacement costs were based on list price data for
typical medical equipment available at the time of this study. Replacement
costs consider only the cost of the component, and do not include ancillary
work required to access or reinstall the damaged component. Assumed
repair times ranged from 7 to 180 days, depending on the damage state and
the cost and complexity of the component. Repair/replacement costs and
repair times for medical component fragilities used in this study are
judgement-based estimates, and should be considered to be lower bound
values. Medical equipment fragilities and consequence data used in this
study are provided in Appendix B.
Performance groups are groups of fragilities that are subjected to the same
demands (e.g., story drift, floor acceleration, or velocity), in a particular
direction, at a particular floor level. Nonstructural component fragilities in
office and healthcare occupancies were based on information from the
Normative Quantity Estimation Tool in FEMA P-58, Volume 3, and
additional assumptions described below.
The types and quantities of nonstructural components are the same for Risk
Category II and Risk Category IV archetypes of the same occupancy. The
specific fragilities, however, vary based on risk category, seismic hazard
level, and location of the component in the structure.
Department block diagrams, such as the diagram shown in Figure 4-2, were
developed for low- and mid-rise healthcare archetypes to determine the
location of medical equipment within the building. Although most
healthcare facilities providing a full array of medical services will have a
larger floor plate than the 14,000 square foot floor area assumed for the
archetypes in this study, the floor area for office and healthcare occupancies
was held constant to allow comparisons between occupancies. Typical
proportions of building area devoted to patient beds, surgical services, and
support services, as depicted in the block diagrams, were maintained in low-
and mid-rise healthcare archetypes.
FEMA P-58 performance metrics include repair costs, repair time, casualties,
and probability of incurring an unsafe placard as direct outputs of the
Performance Assessment Calculation Tool (PACT). In addition, data from
PACT realizations were exported and post-processed to derive additional
metrics identified as casualty rates and repairability.
Concurrent with this work, the FEMA P-58 methodology was expanded to
assess the probability of generating environmental impacts, including
embodied energy and carbon. Because environmental metrics were not
available at the time these performance assessments were initiated,
environmental losses were not considered in assessing the expected
performance of code-conforming buildings.
The parametric variation of strength and stiffness within the design space
could include some combinations of lateral strength and stiffness that are not
realistic for some systems. Representative designs are combinations of
lateral strength and lateral stiffness that are judged to be most typical for each
seismic force-resisting system. Where specifically noted, results for seismic
force-resisting systems are reported for buildings with the properties of
representative designs. Performance results for representative designs are
obtained by averaging the results for archetypes at three or four points in the
design space. Points contributing to the performance of representative
designs for each seismic force-resisting system are identified in Table 5-1.
Risk Category IV structures are designed for higher lateral forces and lower
story drift ratios than Risk Category II structures. At lower shaking
intensities, the reduction in median losses for Risk Category IV Steel SMRF
archetypes is attributed mainly to higher design forces used for the design of
nonstructural components, and enhanced detailing for ceilings and pipe, duct,
and electrical distribution systems. At higher shaking intensities (greater
than 67% MCE), Steel SMRF archetypes benefit from more stringent design
story drift criteria, with substantially reduced structural damage and
unrepairable residual drift.
Figure 5-1 Median repair costs for 13 lateral strength/design story drift ratio combinations, Steel SMRF, Risk
Category II and IV, office occupancies, 100% MCE.
The influence of lateral strength and design story drift ratio on median repair
costs for RC SMRF archetypes can be observed in Figure 5-3, which shows
median repair costs on the design space for RC SMRF, Risk Category II,
office archetypes, subjected to 100% MCE shaking intensity, averaged over
all building heights and hazards levels. In the figure, average median repair
costs for RC SMRF archetypes are significantly influenced by both lateral
strength and design story drift ratio, and archetypes with higher lateral
strengths and smaller design story drift ratios have lower average median
repair costs. Reductions are more significant in Risk Category IV, which
clearly shows the effect of more stringent drift requirements.
Figure 5-3 Median repair costs for 13 lateral strength/design story drift ratio combinations, RC SMRF, Risk
Category II and IV, office occupancies, 100% MCE.
Figure 5-4 Probability of incurring an unsafe placard for 13 lateral strength/design story drift ratio
combinations, RC SMRF, Risk Category II and IV, office occupancies, 67% MCE.
Median losses for Steel BRBF systems shown in Table 5-6 reflect a design
space that includes code minimum required lateral strengths and, for high-
Between Risk Categories, losses in Steel BRBF systems are lower, and
repairability of Steel BRBF systems is higher, for Risk Category IV
archetypes relative to Risk Category II archetypes, in both office and
healthcare occupancies. Within a given Risk Category, losses in Steel BRBF
archetypes for healthcare occupancies are somewhat higher than office
occupancies because of the presence of additional, high-value equipment and
increased (24-hour) occupancy associated with healthcare occupancies.
Higher design forces and lower story drift ratios associated with Risk
Category IV design requirements, as well as higher design forces and
enhanced detailing requirements for nonstructural components, have the
effect of reducing structural damage, unrepairable residual drift, and potential
for nonstructural damage in Steel BRBF archetypes.
The effect of changes in design story drift ratio can be seen in Figure 5-5,
which shows median repair costs on the design space for Steel BRBF, Risk
Category II and IV, office archetypes, subjected to design earthquake (67%
MCE) shaking intensity, averaged over all building heights and hazards
levels. In the figure, average median repair costs for Steel BRBF archetypes
are strongly influenced by design story drift ratio, and archetypes with
smaller design story drift ratios have significantly lower average median
repair costs. Reductions due to Risk Category IV criteria are less significant
in comparison with other systems because assumed design story drifts for
certain Steel BRBF archetypes have already been conservatively reduced,
and taken as less than code maxima across the design space.
Figure 5-5 Median repair costs for 13 lateral strength/design story drift ratio combinations, Steel BRBF, Risk
Category II and IV, office occupancies, 67% MCE.
Figure 5-6 Probability of incurring an unsafe placard for 13 lateral strength/design story drift ratio
combinations, Steel BRBF, Risk Category II and IV, office occupancies, 67% MCE.
Figure 5-7 shows repairability on the design space for Steel BRBF, Risk
Category II, office archetypes, subjected to design earthquake (67% MCE)
shaking intensity, averaged over all building heights and hazards levels.
Note that, in contrast with other performance metrics, repairability is a
positive metric and higher values indicate better performance.
Figure 5-7 Repairability for 13 lateral strength/design story drift ratio combinations, Steel BRBF, Risk Category
II and IV, office occupancies, 67% MCE.
Between Risk Categories, losses in Steel SCBF systems are lower, and
repairability of Steel SCBF systems is higher, for Risk Category IV
archetypes relative to Risk Category II archetypes, in both office and
healthcare occupancies. Within a given Risk Category, losses in Steel SCBF
archetypes for healthcare occupancies are somewhat higher than office
occupancies because of the presence of additional, high-value equipment and
increased (24-hour) occupancy associated with healthcare occupancies.
Brace damage is a major contributor to losses in Steel SCBF systems for both
Risk Category II and Risk Category IV archetypes. Other significant
contributors to loss include residual drift, interior flooding, exterior window
Figure 5-8 shows median repair costs on the design space for Steel SCBF,
Risk Category II and IV, office archetypes, subjected to 100% MCE shaking
intensity, averaged over all building heights and hazards levels. In the figure,
average median repair costs for Steel SCBF archetypes decrease significantly
as the design story drift ratio decreases across the design space, while
variations in lateral strength had comparatively little influence. Reductions
occur across the entire design space under more stringent Risk Category IV
design requirements, showing little variation with strength and stiffness. A
similar trend is observed for average median repair times across the design
space for Steel SCBF archetypes.
Figure 5-8 Median repair costs for 13 lateral strength/design story drift ratio combinations, Steel SCBF,
Risk Category II and IV, office occupancies, 100% MCE.
Although Risk Category IV criteria include higher design forces and lower
design story drift ratios, engineering practice is expected to result in designs
that are significantly stiffer that required, and design story drifts have been
conservatively taken as less than code maximum drift limits in both Risk
Category II and Risk Category IV Steel SCBF archetypes (see Tables 2-5
and 2-6). As a result, Steel SCBF archetypes benefit less from more
restrictive Risk Category IV drift criteria than other systems. Risk Category
IV design requirements reduce, but do not eliminate, damage to nonstructural
components in Steel SCBF systems. Interior flooding still contributes
significantly to losses in Risk Category IV. Also, higher strength and
stiffness in Steel SCBF, Risk Category IV archetypes results in higher floor
Figure 5-9 Probability of incurring an unsafe placard for 13 lateral strength/design story drift ratio
combinations, Steel SCBF, Risk Category II and IV, office occupancies, 67% MCE.
Median results for special reinforced concrete shear wall (Special RCSW)
systems, averaged across all Special RCSW archetype strength and stiffness
combinations, heights, and hazard levels, are summarized in Table 5-10.
Figure 5-10 shows median repair costs on the design space for Special
RCSW, Risk Category II and IV, office archetypes, subjected to 100% MCE
shaking intensity, averaged over all building heights and hazards levels. In
the figure, average median repair costs for Special RCSW archetypes are
relatively low and change very little across the design space, indicating that
variations in lateral strength and design story drift ratio had limited influence
on repair costs.
Figure 5-10 Median repair costs for 13 lateral strength/design story drift ratio combinations, Special RCSW,
Risk Category II and IV, office occupancies, 100% MCE.
Figure 5-11 Probability of incurring an unsafe placard for 13 lateral strength/design story drift ratio
combinations, Special RCSW, Risk Category II, office occupancies, 67% MCE and 100% MCE.
Average median repair costs for each system are summarized in Table 5-12.
Values in the table are based on representative design points for each system,
averaged across all hazard levels (Low SDC D, SDC D, and SDC E/F) and
building heights (low-, mid-, and high-rise). Overall, average median repair
costs increase with shaking intensity, although the magnitude of the values,
and the magnitude of the increase, differs between systems.
Average median repair costs are higher, and the rate of increase with
intensity is more significant in systems identified in Section 5.3 to be more
sensitive to residual drift. These include Steel BRBF and Steel SCBF
systems that showed sensitivity to increases in drift demand, along with
limited capacity for overstrength beyond the design strength. Although
losses in drift-controlled systems (e.g., Steel SMRF and RC SMRF systems)
also include contributions from residual drift, average median repair costs are
lower due to indirect contributions to overstrength caused by proportioning
structural members for increased stiffness. Stiff, strength-controlled systems
(e.g., Special RCSW systems) exhibited lower average median repair costs
Within a given Risk Category, repair costs for healthcare occupancies are
somewhat higher than office occupancies. This is attributed to the presence
of high-value medical equipment and increased (24-hour) occupancy
associated with healthcare occupancies.
Figure 5-12 Comparison of median repair costs for each system, separated by Risk Category and
occupancy, average of representative designs.
Median repair times for each system are summarized in Table 5-13. Values
in the table are based on representative design points for each system,
Overall, average median repair times in Table 5-13 increase with shaking
intensity, although the magnitude of the values, and the magnitude of the
increase, differs between systems. Because repair times are proportional to
repair costs, the relative trends in median repair times between systems are
similar to trends reported for repair costs in Section 5.4.1.
Within a given Risk Category, repair costs for healthcare occupancies are
somewhat higher than office occupancies. This is attributed to the presence
of high-value medical equipment and increased (24-hour) occupancy
associated with healthcare occupancies. Although the time to repair
individual medical components was assumed to be relatively short, the large
number of components present in healthcare occupancies impacted overall
repair times.
Between Risk Categories, repair costs for Risk Category IV archetypes are
lower than Risk Category II archetypes over all shaking intensities, although
the magnitude of the difference varies between systems. This is attributed to
the relative effects of designing Risk Category IV structures for higher lateral
forces and lower story drift ratios than Risk Category II structures.
Median casualty rates by system are summarized in Table 5-14. Results are
based on representative design points for each system, averaged across all
hazard levels (Low SDC D, SDC D, and SDC E/F) and building heights
(low-, mid-, and high-rise).
Figure 5-14 Comparison of median casualty rates for each system, separated by Risk Category and
occupancy, average of representative designs.
Figure 5-15 Comparison of median probabilities of incurring an unsafe placard for each system, separated
by Risk Category and occupancy, average of representative designs.
The most severe damage states in nearly all structural fragility groups are
associated with a potential loss of stability of the structure, triggering an
5.4.5 Repairability
Figure 5-16 Comparison of median repairability for each system, separated by Risk Category and
occupancy, average of representative designs.
Median repair costs at different hazard levels are summarized for Risk
Category II archetypes in Table 5-17 and Risk Category IV archetypes in
Table 5-18. Results are based on representative design points for each
system, averaged across all building heights (low-, mid-, and high-rise), and
occupancies (office and healthcare). Comparative plots are shown in Figure
5-17.
Overall, median repair costs vary significantly between systems. With the
exception of Steel BRBF archetypes (discussed in more detail below), repair
costs increase as the hazard level increases. The increase in design force
with hazard level is not sufficient to maintain the same level of performance
in higher hazard settings. Drift sensitive systems in Low SDC D remain
susceptible to residual drift demands at design earthquake (67% MCE) and
higher shaking intensities, even when ground accelerations are lower.
General trends in relative losses between systems, and the change in losses
with shaking intensity, are consistent across all hazard levels and risk
categories.
Average repair costs for Risk Category IV archetypes are lower than Risk
Category II archetypes across all hazard levels, and the relative performance
of representative Risk Category IV archetypes followed patterns similar to
those of Risk Category II archetypes.
Design story drift limits are the same in Low SDC D, SDC D, and SDC E/F,
but the resulting design strengths and stiffnesses change with changes in
force level. As a result, Steel BRBF archetypes in Low SDC D have longer
effective periods and lower yield strengths compared to archetypes in SDC D
and SDC E/F. Steel BRBF archetypes in Low SDC D are more likely to
experience higher drift demands, and increased likelihood of residual drift,
causing higher repair costs, even in the lower hazard setting. In SDC D, the
higher relative strength and stiffness reduce potential repair costs, even as the
hazard increases. In SDC E/F, the change in strength and stiffness is not
enough to overcome the increase in hazard level, so losses increase at the
higher hazard level.
Median casualty rates at different hazard levels are summarized for Risk
Category II archetypes in Table 5-19 and Risk Category IV archetypes in
Table 5-20. Results are based on representative design points for each
system, averaged across all building heights (low-, mid-, and high-rise), and
occupancies (office and healthcare). Comparative plots are shown in Figure
5-18.
For a given system at a given point in the design space, design story drift
ratios are the same in all hazard settings. As a result, casualties due to
exterior window systems do not vary significantly between hazard levels.
As observed in the case of repair costs, Steel BRBF systems exhibit a non-
typical trend in the probability of incurring an unsafe placard with changes in
hazard level. Median probabilities of incurring an unsafe placard are higher
in Low SDC D, lower in SDC D, and then higher again in SDC E/F. This
trend is observed in Risk Category II archetypes, but not in Risk Category IV
archetypes, and is attributed to changes in the likelihood of residual drift due
to differences in design strength and stiffness, as described in Section 5.5.1.
As a result, Steel BRBF archetypes in Low SDC D are more likely to
experience higher drift demands and increased likelihood of residual drift
relative to SDC D archetypes, even in the lower hazard setting. In SDC E/F,
the change in strength and stiffness is not enough to overcome the increase in
hazard level, so probabilities of incurring an unsafe placard increase at the
higher hazard level.
In each system, archetypes were designed and evaluated for three different
height variants: low-rise (2-story and 3-story), mid-rise (5-story), and high-
rise (12-story). The break between low-rise and mid-rise archetypes was
selected to align with requirements in ASCE/SEI 7-10 Table 12.12-1, which
permit larger story drifts for structures that are four stories or less in height.
To represent high-rise buildings, 12-story archetypes were selected to be
within the upper limit of 15 stories for buildings analyzed using the
simplified analysis procedure in FEMA P-58, Volume 1.
Not all height variants were designed and evaluated in all Risk Categories or
occupancies. To match typical construction practices, Risk Category IV
Median repair costs for low-, mid-, and high-rise office occupancies are
summarized for Risk Category II archetypes in Table 5-23 and Risk Category
IV archetypes in Table 5-24. Results are based on representative design
points for each system, averaged across all hazard levels (Low SDC D, SDC
D, and SDC E/F). Comparative plots are shown in Figure 5-20.
Overall, median repair costs vary significantly by building height and Risk
Category. Trends observed among the variations in height and Risk
Category are attributed most significantly to changes in design story drift
ratio.
In general, low-rise, Risk Category II, office archetypes exhibited the highest
repair costs across all systems. This is attributed to larger design story drift
ratios permitted for low-rise structures in ASCE/SEI 7-10, resulting in a
greater likelihood of residual drift in stronger shaking intensities, especially
in drift-controlled systems (e.g., Steel SMRF and RC SMRF) and drift-
sensitive systems (e.g., Steel BRBF). Low-rise strength-controlled systems
(e.g., Steel SCBF and Special RCSW) experienced higher floor accelerations
and increased losses due to interior flooding, even in lower shaking
intensities.
Mid-rise, Risk Category II, office archetypes benefit from lower design story
drift ratios relative to low-rise archetypes, which reduces the potential for
residual drift in drift-controlled and drift-sensitive systems, and reduces
nonstructural damage to partitions and exterior window systems. Mid-rise
archetypes also have longer effective periods relative to low-rise archetypes,
which reduces floor accelerations and reduces damage to acceleration-
controlled mechanical, electrical, and plumbing equipment and ceiling
systems.
High-rise, Risk Category II, office archetypes are designed for code-
maximum allowable drift ratios, which are smaller than design drift ratios for
low-rise buildings, but larger than design drift ratios assumed for most mid-
rise archetypes. As a result, repair costs for drift-sensitive high-rise
archetypes (e.g., Steel BRBF and Steel SCBF) are lower than repair costs for
low-rise archetypes, but higher than repair costs for mid-rise archetypes.
High rise moment frame and shear wall archetypes exhibit the lowest repair
costs across all building heights.
Design story drift ratios for mid-rise Steel BRBF archetypes are smaller than
low-rise archetypes, and change with Risk Category. In the case of mid-rise
Steel BRBF archetypes, repair costs for Risk Category IV archetypes are
substantially reduced relative to Risk Category II archetypes.
Median repair costs for Special RCSW archetypes are low relative to other
systems across all building heights and Risk Categories.
Median repair costs for low-rise and mid-rise healthcare occupancies are
summarized for Risk Category II archetypes in Table 5-25 and Risk Category
IV archetypes in Table 5-26. Results are based on representative design
points for each system, averaged across all hazard levels (Low SDC D, SDC
D, and SDC E/F). Comparative plots are shown in Figure 5-21.
Overall, median repair costs vary significantly by building height and Risk
Category. As observed for office occupancies, trends among the variations
in height and Risk Category for healthcare occupancies are attributed most
significantly to changes in design story drift ratio.
Design story drift ratios for mid-rise Steel BRBF archetypes are smaller than
low-rise archetypes, and change with Risk Category. In the case of mid-rise
Steel BRBF archetypes, repair costs for Risk Category IV archetypes are
substantially reduced relative to Risk Category II archetypes.
Figure 5-21 Comparison of median repair costs for healthcare occupancies, separated by building
height and Risk Category, average of representative designs.
Generalized performance has been evaluated for two earthquake levels: the
design level earthquake and the Maximum Considered Earthquake (MCE).
The design and MCE earthquake levels are based on ASCE/SEI 7-10 ground
motion values, with design earthquake shaking taken as two-thirds of MCE
shaking. Table 6-1 provides the expected performance for Risk Category II
and Risk Category IV, office and healthcare occupancies, using FEMA P-58
performance metrics, taken as median values of the following measures:
• Repair Cost. The cost to restore damaged components to their pre-
earthquake condition, expressed as a percentage of the replacement value
of the building. Repair costs represent only a single aspect of the
potential financial loss due to earthquake damage. Other costs include
loss of income due to business interruption during repair work, the cost
to identify, plan, and permit the repairs, and the cost of financing the
repairs.
• Repair Time. The number of days required to restore damaged
components to their pre-earthquake condition, which is only a portion of
the time to return a building to its pre-earthquake conditions. Additional
time is required to identify, plan, and permit the work, arrange financing,
and hire and mobilize the contractors.
Codes and standards have long targeted improved performance for higher
occupancy and essential buildings. Recent update cycles have included
aspirational structural and nonstructural reliability criteria attempting to
define what is needed to achieve higher performance. With the ongoing
attention on resilience concepts, and continual evolution of codes to include
more explicit performance-based design concepts, the development of
functional performance criteria is needed.
Table A-1 Range of Structural Properties for Representative Design Points, Steel SMRF Archetypes,
Low SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 2.06 - 2.39 1.75 - 2.03 0.73 0.021 - 0.025 1.0 0.06 2.1 - 3.6
Low-Rise
IV 1.37 - 1.49 1.17 - 1.27 0.73 0.014 - 0.015 1.0 0.09 3.2 - 5.4
II 2.49 - 2.84 2.11 - 2.41 1.11 0.018 - 0.02 1.0 0.04 1.4 - 2.4
Mid-Rise
IV 1.32 - 1.49 1.12 - 1.27 1.11 0.009 - 0.01 1.0 0.06 2.1 - 3.6
II 5.15 - 5.92 4.41 - 5.04 2.23 0.018 - 0.02 1.0 0.02 0.8 - 1.2
High-Rise
IV - - - - - - -
Table A-2 Range of Structural Properties for Representative Design Points, Steel SMRF Archetypes,
SDC E/F
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 1.01 - 1.18 0.86 - 1.00 0.73 0.021 - 0.025 1.0 0.13 4.6 - 7.7
Low-Rise
IV 0.67 - 0.73 0.57 - 0.62 0.73 0.014 - 0.015 1.0 0.23 - 0.25 8.9 - 14.9
II 1.23 - 1.40 1.05 - 1.19 1.11 0.018 - 0.02 1.0 0.08 - 0.09 3.2 - 5.4
Mid-Rise
IV 0.64 - 0.73 0.55 - 0.62 1.11 0.009 - 0.01 1.0 0.23 - 0.25 9.0 - 15.0
II 2.21 - 2.36 1.88 - 2.01 2.23 0.018 - 0.02 1.0 0.05 - 0.05 1.8 - 3.0
High-Rise
IV - - - - - - -
Table A-4 Range of Structural Properties for Representative Design Points, RC SMRF Archetypes,
SDC E/F
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 1.01 - 1.18 0.56 - 0.65 0.61 0.021 - 0.025 0.55 0.15 - 0.17 5.3 - 7.0
Low-Rise
IV 0.67 - 0.73 0.37 - 0.40 0.61 0.014 - 0.015 0.55 0.25 8.0 - 10.5
II 1.23 - 1.40 0.68 - 0.77 0.96 0.018 - 0.02 0.55 0.12 - 0.14 4.4 - 5.8
Mid-Rise
IV 0.64 - 0.73 0.35 - 0.40 0.96 0.009 - 0.01 0.55 0.25 8.0 - 10.5
II 2.21 - 2.36 1.22 - 1.30 2.11 0.018 - 0.02 0.55 0.07 - 0.08 2.5 - 3.2
High-Rise
IV - - - - - - -
Table A-5 Range of Structural Properties for Representative Design Points, Steel BRBF Archetypes,
Low SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 1.04 - 1.29 0.89 - 1.10 0.48 0.01 - 0.0125 0.3 0.06 2.0 - 2.6
Low-Rise
IV 1.04 - 1.29 0.89 - 1.10 0.48 0.01 - 0.0125 0.3 0.09 3.0 - 3.9
II 1.63 - 2.00 1.38 - 1.70 0.96 0.01 - 0.0125 0.3 0.05 1.6 - 1.9
Mid-Rise
IV 1.25 - 1.44 1.06 - 1.22 0.96 0.008 - 0.009 0.3 0.07 2.2 - 2.9
II 3.89 - 5.05 3.30 - 4.29 1.85 0.013 - 0.016 0.3 0.02 0.8 - 1.0
High-Rise
IV - - - - - - -
Table A-7 Range of Structural Properties for Representative Design Points, Steel SCBF Archetypes,
Low SDC D
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 0.53 - 0.79 0.45 - 0.67 0.32 0.005 - 0.01 0.35 0.08 2.0
Low-Rise
IV 0.50 - 0.67 0.42 - 0.57 0.32 0.004 - 0.008 0.35 0.13 3.0
II 0.66 - 1.21 0.56 - 1.03 0.64 0.005 - 0.01 0.35 0.08 2.0
Mid-Rise
IV 0.62 - 1.00 0.53 - 0.85 0.64 0.004 - 0.008 0.35 0.13 3.0
II 1.96 - 3.52 1.66 - 2.99 1.24 0.009 - 0.016 0.35 0.05 1.1
High-Rise
IV - - - - - - -
Table A-8 Range of Structural Properties for Representative Design Points, Steel SCBF Archetypes,
SDC E/F
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 0.32 - 0.46 0.28 - 0.39 0.32 0.005 - 0.01 0.35 0.22 5.3
Low-Rise
IV 0.30 - 0.41 0.26 - 0.35 0.32 0.004 - 0.008 0.35 0.33 8.0
II 0.41 - 0.59 0.35 - 0.50 0.64 0.005 - 0.01 0.35 0.22 5.3
Mid-Rise
IV 0.38 - 0.52 0.33 - 0.44 0.64 0.004 - 0.008 0.35 0.33 8.0
II 0.98 - 1.72 0.84 - 1.47 1.24 0.009 - 0.016 0.35 0.10 - 0.15 2.4 - 3.6
High-Rise
IV - - - - - - -
Table A-10 Range of Structural Properties for Representative Design Points, Special RCSW Archetypes,
SDC E/F
Periods Drift Ratios Strengths
Bare- Upper Yield Minimum Inferred
Frame Effective Limit Drift Base Shear Collapse
Risk Period, Period, Period, Design Story Ratio Coefficient, Capacity,
Height Category T1,BF T1,EFF Tmax Drift Ratio (%) Cs g
II 0.18 - 0.29 0.16 - 0.26 0.32 0.003 - 0.006 0.5 0.27 6.0 - 10.0
Low-Rise
IV 0.18 - 0.29 0.16 - 0.26 0.32 0.003 - 0.006 0.5 0.40 9.0 - 15.0
II 0.25 - 0.40 0.23 - 0.36 0.64 0.003 - 0.006 0.26 0.27 6.0 - 10.0
Mid-Rise
IV 0.25 - 0.40 0.26 - 0.36 0.64 0.003 - 0.006 0.26 0.40 9.0 - 15
II 0.83 - 1.15 0.75 - 1.04 1.24 0.009 - 0.013 0.63 0.14 - 0.20 4.3 - 7.5
High-Rise
IV - - - - - - -
At the low SDC D hazard level, spectral response acceleration parameters are
lower, than SDC D parameters. The resulting base shear strengths of
representative low SDC D archetypes are lower, the effective stiffnesses are
lower, and the resulting periods are longer relative to values for SDC D
archetypes.
Table B-1 Representative Nonstructural Fragilities, Typical Floor, Direction 1, Mid-Rise Office
Occupancies, Risk Category II
Normative
ID Group Description Quantity
ID Description Quantity
ID Description Quantity
E1028.001a Anesthesia Machine 4
E1028.002a Balloon Pump 2
E1028.003a Catheter Cabinet 1
E1028.004a Blood Recovery System 1
E1028.005a Hypothermia System 2
E1028.006a Surgical Table 4
E1028.011a Patient Bed 6
Equipment Boom – Risk Category II, SDC D,
E1028.101d 4
x/h = 0.2 – 0.25
Warming Cabinet – Risk Category II, SDC D,
E1028.102d 4
x/h = 0.2 – 0.25
Anesthesia Boom – Risk Category II, SDC D,
E1028.103d 4
x/h = 0.2 – 0.25
ID Description Quantity
E1028.011a Patient Bed 12
E1028.301c Headwall – Risk Category II, SDC D, x/h = 0-0.5 12
E1028.311f Ice Dispenser – Risk Category II, SDC D, x/h = 0.6 1
Under Counter Refrigerator – Risk Category II, SDC D,
E1028.321f 2
x/h = 0.6
E1028.341f Medstation – Risk Category II, SDC D, x/h = 0.6 1
ID Description Quantity
E1028.031a Cryostat 1
Bio Safety Hood – Risk Category II, SDC D
E1028.201d 2
x/h = 0.8
Laminar Flow Hood – Risk Category II, SDC D,
E1028.204d 1
x/h =0.8
Chemistry Analyzer – Risk Category II, SDC D,
E1028.221d 1
x/h = 0.8
E1028.331d Refrigerator – Risk Category II, SDC D, x/h = 0.8 2
Shelving System – Risk Category II, SDC D,
E1028.501d 5
x/h = 0.8
Medical equipment fragility and consequence data are not available in the
default PACT fragility database. Fragility and consequence data for fixed
and mobile medical equipment used in this study are summarized in Table
B-13 and Table B-14.
Repair and replacement costs were based on available or estimated list price
data for typical medical equipment. Repair costs were taken as 10% of
replacement cost. Replacement costs consider only the cost of the
component, and do not include ancillary work required to access or reinstall
the damaged component. Repair times range from 7 to 180 days, depending
on the damage state and the cost and complexity of the component.
Replacement costs and repair times for medical components are judgement-
based estimates, and should be taken as lower bound values.
C.1 Introduction
Figure C-1 shows the PET User Interface tab. The left side of the tab is the
user input interface. The user may select any combination of seismic force-
resisting system, occupancy type, Risk Category, building height, and
seismic hazard from the available options. Risk Category II office
occupancies will allow selection of low-, mid-, and high-rise buildings, but
healthcare occupancies and Risk Category IV office occupancies are limited
to low- and mid-rise selections. The available gradient in seismic hazard
level (i.e., Low SDC D, SDC D and SDC E/F) is representative of the
Seismic Design Category D-E transition. The figure shows the tool with the
following selections: special steel moment-resisting frame (“Steel SMRF”),
“office” occupancy, Risk Category “II”, “mid-rise” building height, and
“SDC D” hazard level.
Figure C-2 shows the stiffness and strength input interface, including the
design space graphic, which shows the boundaries of the design space for the
selected seismic force-resisting system. Each point within the design space
is characterized by a design story drift ratio and design strength expressed as
a multiple of minimum base shear. The green dot indicates the location of
the representative design within the design space. The red dot reflects the
current selection of stiffness and strength within the design space. The red
dot can be moved using the sliders located along the bottom and right side of
the design space, or through selections from dropdown menus associated
with the buttons for multiple of minimum base shear and design story drift.
In the figure, input fields indicate the selection of a design story drift ratio of
0.015 and base shear ratio of 2.5.
Once data have been entered, the User Interface tab provides graphs showing
estimates of building performance in terms of median, mean, and 90th
percentile repair costs and repair times; probability of collapse; probability of
reparability; and probability of unrepairable permanent drifts for different
intensities of ground motion expressed as a percentage of the MCE shaking
intensity at the building site. A change in any of the input parameters
automatically updates all of the graphs.
Figure C-3 provides an example of one graph showing mean repair cost
expressed as percentage of replacement cost. In all graphs, a blue shaded
area indicates the range of performance (ROP) for all buildings within the
design space. A green line indicates the performance of the representative
design (RD) for the selected system, and a red line indicates the performance
of the current search (CS) parameters including the selected values of story
drift ratio and base shear multiple. Performance values for current search
(CS) parameters are also tabulated below the graph at each intensity level.
The Detailed Plots tab provides all data for the parameters currently selected
in the User Interface tab in larger scale and with additional detail. The tab
displays one detailed plot at a time for the selected performance metric.
Results for different performance metrics can be accessed through gray-
shaded buttons on the left side of the tab. Figure C-4 provides a detailed plot
of mean repair cost versus intensity, which is a more detailed version of the
information shown in Figure C-3. Similar to Figure C-3, the red line shows
the performance of the current search parameters, and the green line shows
the performance of a representative building design for the selected system.
The two blue lines indicate an upper and lower bound characterizing the
range of performance considering all buildings within the design space. The
performance of the current search, representative design, and bounds for the
performance range are also tabulated below the plot.
ASCE, 2010, Minimum Design Loads for Buildings and Other Structures,
ASCE/SEI 7-10, American Society of Civil Engineers, Reston, Virginia.
ASCE, 2013, Minimum Design Loads for Buildings and Other Structures,
ASCE/SEI 7-10 including Supplement No. 1, American Society of Civil
Engineers, Reston, Virginia.
ASCE, 2017a, Minimum Design Loads and Associated Criteria for Buildings
and Other Structures, Provisions, ASCE/SEI 7-16, American Society of
Civil Engineers, Reston, Virginia.
ASCE, 2017b, Minimum Design Loads and Associated Criteria for Buildings
and Other Structures, Commentary, ASCE/SEI 7-16, American Society
of Civil Engineers, Reston, Virginia.
Harris, A., Naeim, F., and Zareian, F., 2016, Development of Fundamental
Period Adjustment Factors for Buildings in Low-To-Moderate Seismic
Excitation, FEMA P-58/BD-3.7.17 Report, Applied Technology Council,
Redwood City, California.
Newmark, N.M., and Hall, W.J., 1982, Earthquake Spectra and Design,
Earthquake Engineering Research Institute, Oakland, California.
Saldana, D., and Terzic, V., 2018, Simplified Analysis Response Models for
SCBF and BRBF Compliant with FEMA P-58 Simplified Procedures,
FEMA P-58/BD-3.7.21 Report, Applied Technology Council, Redwood
City, California.
Russell Larsen
Magnusson Klemencic Associates
1301 Fifth Avenue, Suite 3200
Seattle, Washington 98101