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Research Paper

International Journal of Informative & Futuristic Research ISSN (Online): 2347-1697

Volume 2 Issue 9 May 2015

Abstract

During an earthquake, buildings are strongly affected by the rigidity of floors and the connections of floors to the walls. Shear walls are normally arranged in such a way that they resist lateral loads most effectively. Therefore, in the present study the structural behavior of the buildings with shear walls at corners has been investigated. A geometrically unsymmetrical building situated in the most prone seismic zone-v as per IS 1893-2002(part-1). it has been outlined that the RC building model consisting of G+5 storey’s is considered and analyzed using both linear static or equivalent static & non-linear static or pushover analysis, for the loads considered as per IS 875 -2000. Also various results such as base shear, storey displacement, storey drift, storey shears, maximum drift, maximum lateral displacement and nonlinear results performance point, performance levels, capacity of the building and hinge status are obtained and these results are Compared for both linear and non-linear analysis, for the gravity load combination as per IS 1893 (part-I) 2002. Modelling and analyzing the considered RC frame building is done using extended three dimensional FEM based analytical software ETABS-9.7.4 version.

Seismic Vulnerability Of Geometrically

Unsymmetrical RC Building By Considering

The Effect Of Shear Walls At Different Position Paper ID IJIFR/ V2/ E9/ 066 Page No. 3420-3428 Research Area

Structural

Engineering

Key Words Shear Wall, Lateral Displacement, Drift, Base Shear, Pushover Analysis

Harsha N C 1 M.Tech. Scholar Department Of Civil Engineering ACS College Of Engineering, Bangalore, Karnataka

Kavitha K 2 Assistant Professor Department Of Civil Engineering ACS College Of Engineering, Bangalore, Karnataka

Syed Ahamed Raza 3 Assistant Professor Department Of Civil Engineering Ghousia College Of Engineering, Ramanagaram, Karnataka

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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)

Volume - 2, Issue - 9, May 2015 21st Edition, Page No: 3420-3428

Harsha N C, Kavitha K , Syed Ahamed Raza:: Seismic Vulnerability Of Geometrically Unsymetric RC Building By Considering The Effect Of Shear Walls At Different Position

1. Introduction RC Multi-Storey Buildings are adequate for resisting both the vertical and horizontal load. When

such building is designed without shear wall, the beam and column sizes are quite heavy, steel

quantity is also required in large amount thus there is lot of congestion at these joint and it is

difficult to place and vibrate concrete at these places and displacement is quite heavy which induces

heavy forces in member. Shear wall may become imperative from the point of view of economy and

control of lateral deflection. In RC multi-storey building R.C.C. lift well or shear wall are usual

requirement. However, on many occasions the design has to be based on the off centre position of

lift and stair case wall with respect to centre of mass which results into an excessive forces in most

of the structural members, unwanted torsion moment and deflection. The use of shear wall structure

has gained popularity in high rise building structure, especially in the construction of service

apartment or office, commercial tower. It is very important to note that shear walls meant to resist

earthquake should be designed for ductility.

2. Methodology

Review of existing literatures by different researchers.

Selection a type of structure.

Modelling of the selected structures.

Analyzing the selected structure by using linear static and non-linear static or push over

methods.

G+5 RC building frame models are considered (SMRF) under seismic zone-V for the hard

soil type-2 and response reduction factor R=5 as per IS 1893-2002(part-1).

For the load combination as per IS 1893 (part-1) 2002.

Plotting pushover curve and obtaining various results as mentioned in abstract.

Finally comparing the results of analyzed models by “analysis to analysis” the conclusion has

given.

3. Methods Of Analysis

3.1 Linear Static Analysis

In linear static procedures the building is modelled as an equivalent single degree of freedom

(SDOF) system with a linear static stiffness and an equivalent viscous damping. The seismic input is

modelled by an equivalent lateral force with the objective to produce the same stresses and strains as

the earthquake it represents. The time period of the building is calculated by the expressions

T=0.075h0.75

for bare frame as given in IS 1893 (Part 1): 2002, where h is the height of the building

in the considered direction of vibration. The lateral load calculation and its distribution along the

height are done as per IS 1893 (Part 1): 2002. The seismic weight is calculated using full dead load

plus 50% of live load. For the equivalent static load analysis the earthquake load is considered in

both X and Y directions.

3.1.1 Modelling

Building Data For Analysis And Modelling:

A multi-storey building is considered with G+5 number of stories with geometrically unsymmetrical

in plan . The dimensions of the building elements are given below

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Table 1: Structural Data Used:

Modelling has been done and all the dimension of the cross sectional elements of structure,

characteristics compressive strength, yield strength and other required parameters are defined.

The loads on the structure considered as per IS 875-2000. where in as per IS 1893 (part1) 2002,

percentage of imposed load considered as 50%.

The building model is analysed using linear static analysis, the building is situated in sever zone-

V having importance factor I=1 and response reduction factor R=5, the building is situated on

medium soil(type-2).

The defined parameters are assigned to building model and then the building model is analysed

and design for gravity load combination.

Figure 1: Plan (Location Of Shear Wall At Corner)

01 Types of structure Multi Storied RC Rigid Jointed Plane Frame

(Special Moment Resisting Frame)

02 Number of stories G+5

03 Seismic zone V (Table 2, IS 1893 (Part- 1):2002)

04 Importance factor 1

05 Response reduction factor 5

06 Floor height 3m

07 Size of column 650X750 mm

08 Size of beam 400X600 mm

09 Depth of slab 125mm

10 Thickness of shear wall 200mm

11 Imposed load 3.5 KN/m2 on floors

1.75 KN/m2 on roof

12 Floor finish 2 KN/m2

13 Specific weight of infill 18 KN/m3

14 Specific weight of RCC 25 KN/m3

15 Type of soil Medium soil(type-2)

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Figure 2: Three Dimensional View (Location Of Shear Wall At Corner)

3.2 Non-Linear Static Analysis

Pushover analysis is one of the methods available to understand the behaviour of structures

subjected to earthquake forces. As the name implies, it is the process of pushing horizontally with a

prescribed loading pattern incrementally until the structure reaches a limit state (ATC-40 1996). The

static approximation consist of applying a vertical distribution of lateral loads to a model which

captures the material nonlinearity of an existing or previously designed structure, monotonically

increasing those loads until the peak response of the structure is obtained on a base shear v/s roof

displacement plot.

4. Results Of Analysis

4.1 Storey Shear

The following Table-2 and chart-1shows storey shear for both linear and non-linear static analysis in

longitudinal x direction.

Table 2: Storey Shear

Storey Shear In Kn

Storey Shear Wall At Corner

EQX PUSHX

5 2521.64 49216.58

4 4434.65 86553.91

3 5510.71 107556.2

2 5988.96 116890.5

1 6108.53 119224

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0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

1 2 3 4 5 6

Dis

pla

cem

en

t In

M

STOREYS

EQX

PUSHX

Chart 1: Storey Shear Profile

4.2 point Displacement

The following Table-3 and chart-2shows point displacement for both linear and non-linear static

analysis in longitudinal x direction.

Table 3: Point Displacement

Chart 2: Point Displacement Profile

49216.58

86553.91

107556.16

116890.49

119224

STOREY SHEAR IN kN

STO

REY

S

PUSH X

EQX

point displacement in Meter

Storey shear wall at corner

EQX PUSHX

5 0.002203 0.079418

4 0.0018 0.06141

3 0.0013 0.042347

2 0.0007 0.023967

1 0.0003 0.0086

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4.3 Storey Drift

The following Table-4 and chart-3 shows storey drift for both linear and non-linear static analysis in

longitudinal x direction.

Table 4: Storey Drift

Storey Drift In Meter

Storey

Shear Wall At Corner

EQX PUSHX

5 0.000154 0.006215

4 0.000176 0.006556

3 0.000176 0.006296

2 0.000153 0.005224

1 0.000094 0.002923

Chart 3: Storey Drift Profile

4.4 Non-Linear Static(pushover) Analysis Results

4.4.1 Pushover Curve

Figure 3: Pushover Curve In X Direction

0

0.002

0.004

0.006

0.008

1 1.5 2 2.5 3 3.5 4 4.5 5

EQX PUSH X

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Figure 3: Pushover Curve In Y Direction

Chart 4: Pushover Curve Profile

0 12429.3027

103972.6712

121791.4844 119224.0703

0

20000

40000

60000

80000

100000

120000

140000

-0.02 0 0.02 0.04 0.06 0.08 0.1

PO CURVE Linear (PO CURVE)

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4.4.2 Performance Level

The following Table-5 shows the performance level of the building

Table 5: performance level

Step Displacement Base Force

A-B

B-I

O

IO-L

S

LS

-CP

C-D

D-E

>E

Total

0 0 0 3446 4 0 0 0 0 0 3450

1 0.0045 12429.3027 2651 666 131 2 0 0 0 3450

2 0.0646 103972.6712 2594 540 292 20 3 0 0 3450

3 0.0798 121791.4844 2594 540 292 20 3 1 0 3450

4 0.0788 119224.0703 3450 0 0 0 0 0 0 3450

5. Conclusions

The present work focuses on study of seismic performance evaluation of G+5 RC buildings, which

are located in seismic zone-V for the medium soil condition. These conditions are considered as per

IS 1893-2002 (part-1). The analysis has been carried out using standard package ETABs software.

The analysis results were taken in terms of point Displacements, Storey Drifts, and Storey Shear and

the Performance level of the buildings were tabulated on the basis of linear and non-linear static

analysis. The following are the conclusions are drawn from the present investigation, which are as

follows

Various results such as storey shear, storey displacement and point displacement are

obtained and comparison is done for both linear and non-linear static analysis in longitudinal

X direction.

From the obtained values for various results as shown in the Table 2 to Table 4 and values

are plotted as shown from the chart number 1 to 3 shows that storey shear, point

displacement and storey drift is maximum in non-linear static analysis compared to linear

static analysis, which gives the interference that as storey height increases the values of

storey shear, point displacement and storey drift.

The performance of building is studied and pushover curve is plotted for displacement in X

axis and base forces in Y axis in both X&Y direction.

The building performance is obtained from the non-linear static analysis which shows that

the building performance level lies in the range B-IO (linear range to immediate occupancy).

From this we can interference that the performance level within the immediate occupancy.

References

[1] S.A. Halkude, C.G. Konapure and S.M.Birajdar(2015), “Effect of Location of Shear Walls on Seismic

Performance of Buildings” ijcet, E-issn 2277-4106, P-issn 2347-5161. Volume 5, april 2015

[2] Raman Kumar, Shagunveer Singh Sidhu, Shweta Sidhu, Harjot Singh Gill (2014), “Seismic Behavior

Of Shear Wall Framed Buildings” ijetmas, pp no: 28-38 volume 2 issue 1.

[3] M. S. Aainawala, Dr. P. S. Pajgade (2014), “Design of Multistoried R.C.C. Buildings with and

without Shear Walls”, ijesrt, pp no: 498-510 july 2014.

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[4] Manohar K, Dr. Jagadish Kori(2014), “Analysis On Seismic Performance Of High Rise Building By

Changing The Location Of Shear Wall For Different Soil Condition” ijet, issue 4, volume 4, issn

2249-6149, june-july 2014

[5] Mr. Syed Owaise Showkath Peer, Khalid Nayaz Khan(2014), “Seismic Vulnerability of RC Buildings

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[6] . C.M. Ravi Kumar, M. B. Sreenivasa, Anil Kumar, M. Vijay Sekhar Reddy (2013), “Seismic

Vulnerability Assessment Of RC Buildings With Shear Wall” ijera, pp no: 646-652, vol. 3, issue 3,

may-jun 2013.

[7] Shahzad Jamil Sardar and Umesh. N. Karadi(2013), “Effect Of Change In Shear Wall Location On

Storey Drift Of Multistorey Building Subjected To Lateral Loads” ijirset, issn:2319-8753, volume 2,

issue 9, September 2013.

[8] Kasliwal Sagar K , Prof. M.R.Wakchaure , Anantwad Shirish (2012), “effects of numbers and

positions of shear walls on seismic behavior of multistory structure” ijair, pp no: 189-193, pp no:

189-193, issn: 2278-7844

[9] Applied Technology Council (ATC-40 1996),

[10] IS 1893(Part 1):2002 “Criteria For Earthquake Resistant Design of Structures” BIS, New Delhi

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