Problem Definition

In the Present work 6 different building models has been developed for RCC, for
different position of Soft Storey situated in zone III with subsoil Type medium -II were
analyzed in ETAB software. Non linear static push over analysis is used. L-shape models
will be analysed using software. Model 1 is G+5 building with soft storey at 3rd floor,
model 2 is G+7 building with soft storey at 5th floor , model 3 is G+9 building with soft
storey at 8th floor, model 4 is G+11 building with soft storey at 10th floor, in model 5
G+13 building is cosidered with soft storey at different floors i.e soft storey at 3rd, 5th,
8th & at 10th storey , 6th model is of regular L-shaped G+13 building. Different
parameters such as base shear, storey displacement, storey drift, mode shapes will be
analysed in ETABS. For validation purpose we are going to conduct shake table
experiment on G+5 building model by calculating storey dispalcement and comparing it
with software result

G+5 Models of multi storied braced and unbraced frame models for
different storey number are analyse in software considering seismic zone and evaluated
its structural performance with respect to member strength, displacement, base shear,
vertical displacement and inter storey drift. Equivalent static method and dynamic
method used for seismic analysis and the results are verified by software. The results of
all 12 type of models are analysed on software and actual model check on shake table for
validation of analytical result obtained from software.
The steel building used in this research is multi-storied and problem is
considered for different storey numbers with and without soil mass.
The steel concrete composite building used in this study is ten storied (G+6).
building have same floor plan with5 bays having 4m distance along longitudinal
direction and 3 bays having 5m distance along transverse direction as shown in
figure.
 Fig 4.1: Building Plan

4.2 DESIGN DATA

Model 1- Composite floors are designed based on limit state design philosophy.
Since IS 456:2000 is also based on limit state methods, the same has been
followed wherever it is applicable. The design should ensure an adequate degree
of safety and serviceability of structure. The structure should therefore be checked
for ultimate and serviceability limit states.

(a) Design data

Model: G+5

Seismic zone: III

Zone factor: 0.16

Importance factor: 1

Height of building: 31.5 m

Floor height: 3.00m

Depth of foundation: 1.5 m

Plan size: 20 m X 15 m
Type of soil: Medium

Slab depth: 120 mm thick for R.C.C.

Wall thickness: 230 mm.

(b) Material Properties

Unit weight of masonry: 20kN/m3

Unit weight of R.C.C.: 25kN/m3

Unit weight of steel: 79kN/m3

Grade of concrete: M20 for R.C.C and Steel.

Grade of steel: HYSD bars for reinforcement Fe 415

Modulus of Elasticity for R.C.C.: 5000 X √fck N/mm2

Modulus of Elasticity for Steel: 2.1 x 105 N/mm2

(c) Load Consideration

Dead load: Self Weight
Live load
Floor finish load
Seismic load

(d) Load Combination Consideration:

Load combinations as per IS 1893-2002

(e) Dimensions consideration for design:

For steel frame

Beam size: ISMB 300 @ 54.4 kg

Column size: ISHB 500 @49.4kg

 The steel damping used is ISA 110X110X10.

Codes for analysis

RCC design: IS 456:2000

Composite design: IS 11384

MANUAL DESIGN

DESIGN OF TWO WAY SLAB

Type of slab- one way /two way. Two way

Effective Span of slab along SS lx = 5.00 m

Effective Span of slab along LS ly = 5.00 m

ax (for ly /lx = 1.020) = 0.0644

ay = 0.0618 CONCRETE

Clear cover = 20 mm 10

Grade of concrete used = M25

15

Grade of steel used = Fe500 20

Diameter of bar used Along SS = 10 mm

25

Diameter of bar used Along LS = 8 mm

30

Bar spacing along short span = 150 mm

35

Bar spacing along long span = 200 mm

40
Thickness of slab provided = 150 mm
45

50

Actual load on slab

Dead Load = 3.75 kN/m2 1.000

live load = 4.00 kN/m2 1.020

Floor finish Load on slab = 1.00 kN/m2

1.1

Total load on slab = 8.75 kN/m2

Factored load 1.5(DL+LL) = 13.125 kN/m2

B.M.Calculations

Maximum moment along SS Mx = ax x w x lx2 = 21.13 kN-m

(From STAAD pl. 31743LC119)

Maximum moment along LS My = ax x w x lx2 = 20.28 kN-m

(From STAADpl 31729 LC 125)

RCC design : ly/lx

Effective depth of slab, d= Thk-(cover + Φ/2) = 125.00

mm ax

Main Steel reqd Ast =(0.5fckbd/fy)(1-√1-4.6M/fckbd2) = 416.58

mm2 ay

Spacing of 10mm bar required = 188.53 mm c/c> Spacing

provided, OK

Provide #10 @ 150 mm c/c at bottom along short span

Effective depth of slab, d= Thk-(cover +Φ+Φ/2) = 116.00

mm

Main Steel reqd Ast =(0.5fckbd/fy)(1-√1-4.6M/fckbd2) = 434.64

mm2
Spacing of 8mm bar required = 115.65 mm c/c< Provided, Reduce
Bar Spacing

Provide #8 @ 200 mm c/c at bottom along long span

Distr. Steel for provided grade of steel = 0.12 %

Min. Ast along long span = 180.00 mm2 < Ast requd, OK

Bar spacing for Ast min = 279.25 mm c/c

Deflection check

fs = 0.58 fy Ast reqd/Ast prov = 364.50 N/mm2

Percentage of tension reinforcement = 0.35 %

Modification factor from table 4 IS 456 2000 = 1.100

Depth required for continuous span = 140.83 mm Increase depth

DESIGN OF BEAM

• Step I.

Design load calculation:

the following load factors are chosen.

LDγ and LLγ are taken as 1.50 and 1.50 respectively.
γLD – partial safety factor for dead or permanent loads

γLL – partial safety factor for live or imposed loads

Self weight of beam-47.2 kN / m
Load from slab-W*Lx/3=4*5/3=8 kN/m
Total factored load = 1.50× 8 + 1.50 × 47.2= 82.8 kN / m
Factored bending moment = 82.8 × 52 /8 = 258.504 kN – m

Z—value required for fy=250 MPa ; γm =1.10

Zreqd = 658.02 cm 3

Try ISMB 300

D = 300 mm
B = 140 mm
t = 7.5 mm
T = 12.4 mm

Izz = 8603.6 cm4

I 4
yy = 453.5 cm

Section classification:
Flange criterion = B/2T = 5.0

Web criterion = (D – 2T)/t = 32.61

Since B/2T <9.4 ε & (D-2T)/t < 83.9 ε

The section is classified as ‘ PLASTIC

Moment of resistance of the cross section:

Since the section considered is ‘PLASTIC’
Md = mypfZγ×

Where Zp is the plastic modulus

‘Zp’ for ISMB 300 = 659.76 cm3

Md = 459.76 × 1000 × 250 /1.10

= 104.49 kN-m > 97.504 kN-m

Hence ISMB-300 is adequate in flexure.

Shear resistance of the cross section:

This check needs to be considered more importantly in beams where the maximum
bending moment and maximum shear force may occur at the same section
simultaneously, such as the supports of continuous beams. For the present example this
checking is not required. However for completeness this check is presented.

Shear capacity

Av =250 × 6.9 = 1725 mm2

Vc = 0.6 × 250 × 1725 /1.10 =235.3kN

V = factored max shear = 86.67 × 3 / 2 =130.0 kN

V /Vc =130/235.3 = 0.55 < 0.6

Hence the effect of shear need not be considered in the moment capacity calculation.

Check for Web Buckling:

The slenderness ratio of the web = LE/ry = 2.5 d/t =2.5 × 194.1/6.9

=70.33
The corresponding design compressive stress fc is found to be

fc = 203 MPa (Design stress for web as fixed ended column)

Stiff bearing length = 100 mm

450 dispersion length n1 = 125.0 mm

Pw = (100 + 125.0) × 6.9 × 203.0

= 315.16 kN
315.16 > 126 Hence web is safe against shear buckling
Check for web crippling at support

Root radius of ISMB 300= 13 mm

Thickness of flange + root radius = 25.5 mm

Dispersion length (1:2.5) n2 = 2.5 x 25.5 = 63.75 mm

Pcrip = (100+63.75) × 6.9 × 250 / 1.15

= 245.63 kN > 126kN

Hence ISMB300 has adequate web crippling resistance

Check for serviceability – Deflection:

design load = 57.78 kN/m.

=5.3mm < L/200

Hence O.K

DESIGN OF COLUMN

Factored Axial load of column-1.5*82.8*5*2=1242kN

Assuming fcd=135 N/mm2

Area required =1242*103/135=9200mm2

Using ISHB 500@907N/m

D = 300 mm
B = 140 mm
t = 7.5 mm
T = 12.4 mm
Izz = 8603.6 cm4

I 4
yy = 453.5 cm

Check for factored load

Effective length=KL=0.8*3000=2400

tf from I section=13.7<40mm

Therefore it belongs to buckling class c @ y-y axis

Fcd required =165.5

Pd=Ae**Fcd=31789*165.5=5261kN >Factored Load Hence safe