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Full Paper Proc. of Int. Conf. on Advances in Civil Engineering 2012

Effect of Shear Wall Configuration on Seismic Performance of Building Ehsan Salimi Firoozabad1, Dr. K. Rama Mohan Rao2, Bahador Bagheri3 1.Post Graduate Student, Civil Engineering Department, JNTU Hyderabad, India ehsansalimy.f@gmail.com 2.Professor and Head of Department, Civil Engineering Department, JNTU Hyderabad, India rkunapareddy@yahoo.com 3. Post Graduate Student, Civil Engineering Department, JNTU Hyderabad, India bahador_baghery@yahoo.com

Index Terms—Shear wall configuration, Reinforced concrete building, Seismic performance of building, Time history analysis, Top story displacement

(2000). Ref. [5] in Young-Hun Oh (2006) study, the level of demands for deformation of shear walls was investigated using a displacement-based design approach.[6] R.K.L. Su (2008) reviews the seismic engineering research conducted in Hong Kong with special emphasis on the prediction of seismic drift demand and capacity of existing buildings which have not been designed. [7] Kenneth A. Gent Franch (2008) proposed the vulnerability index for masonry buildings was modified to apply in confined masonry buildings and to obtain a reasonable relationship with the wall density per unit floor index. [8] the dynamic response of high rise structures under the influence of discrete staggered shear walls has been studied by B. Kameshwari (2011).

The main objective of the research work presented in this paper is to study the seismic behavior of reinforced concrete shear wall buildings with respect to shear wall configurations.

Four buildings with same plan and different number of stories (10, 15, 20, and 25) have been modeled considering six various shear wall configuration.[9] the criteria for structural performance of shear wall can be represented by the deformation demand inherent in the structure. The displacement demand of buildings can be obtained when these structures are submitted to real action of earthquake.

The ELCENTRO and TABAS earthquakes are used for this purpose.

I. INTRODUCTION

II. MODELING THE PROBLEM

Shear walls are vertical elements of the horizontal force resisting system.[1] Shear walls are like vertically-oriented wide beams that carry earthquake loads transfers to the foundation. Shear wall system is often used for resisting the lateral forces caused by seismic excitation, because of their high stiffness and strength.[2] Shear wall can be used effectively for controlling the drift against seismic loads acting on them.Mete A. Sozen (1989) is presented the critical structural parameters of shear wall building to relate drift response to intensity of ground motion in an effort to answer design questions about the required amount of details and walls.[4] In order to evaluate seismic performance of confined masonry buildings a methodology that compares displacement demands imposed by real earthquakes and their displacement capacities are proposed by Maximiliano Astroza

Four buildings have been considered with same plan as shown in figure 1 and different number of stories. Six different configurations of shear wall are considered for all buildings.

The buildings are considered in zone V, with importance factor of 1.5, response reduction factor of 5, and medium soil condition. All loads such as: Dead, Live, and Earthquake loads have been calculated and applied on building. Ref. [10] the load combinations are considered based on IS 1893 and the model has been analyzed and designed based on Indian Standard Codes using SAP 2000 software package.

Shear wall configuration: Total six configurations have been considered for all buildings to evaluate the effect of shear wall configuration on seismic performance of building. Each configuration of shear walls is shown in different figure and named as shown in fig [2-7].

Abstract—One of the most commonly used lateral load resisting systems in buildings is shear wall system. It is well-established fact that shear walls are quite effective in seismic load resistance of medium-rise to high-rise reinforced concrete buildings. Shear walls have very high in-plane stiffness and strength, which can be used simultaneously to resist large horizontal loads and support gravity loads, making them quite beneficial in seismic performance of buildings. Lot of literature is available to design and analysis of shear wall; the effect of different parameters such as: time period, wall density, slenderness ratio, on seismic behavior of shear wall buildings has been studied as well. However, the decision about the location of shear wall in multistory building and its effect on performance against earthquakes is not much discussed in the literatures.

In the present study main focus is to determine the effect of shear wall configuration on seismic performance of buildings.

Time history analysis has been done to buildings with different number of stories and various configurations with same plan.

The top story displacements have been obtained and compared to each other for all models to meet the effect of shear wall configuration on seismic performance of buildings. The analysis and design of models have been studied based on IS codes, and SAP 2000 software have been used for this purpose.

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Full Paper Proc. of Int. Conf. on Advances in Civil Engineering 2012

Fig. 1. Base plan of buildings

Fig. 2. First shear wall configuration

Fig. 3. Second shear wall configuration

Fig. 4. Third shear wall configuration

Fig. 5. Fourth shear wall configuration

Fig. 6. Fifth shear wall configuration

Fig. 7. Sixth shear wall configuration

III. DETERMINATION OF DISPLACEMENT DEMAND

Earthquake Engineering Research Center.The top story displacement of each building in X and Y direction with various configuration of shear wall is obtained and classified for ELCENTRO and TABAS earthquake. The values have been read from one joint of roof level in both negative and positive direction. So the largest value among those four values has been considered and given in table I, as maximum displacement of building.

The criteria for the structural performance of a shear wall can be represented by the deformation demand of structure.

The displacement demand of buildings can be obtained when these structures are submitted to real action of earthquake (time history analysis). The ELCENTRO and TABAS earthquakes are used for this purpose. Ref. [11] these recorded accelerograms have been elicited from Pacific

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Full Paper Proc. of Int. Conf. on Advances in Civil Engineering 2012 TABLE I. MAXIMUM TOP STORY DRIFT

IV. CODE LIMITATION OF STORY DRIFT

BUILDING

which are close to 1, indicates that the equations are accurate to find maximum mean drift. The mean drift values shown in fig [8-13] should be less than permissible drift based on IS 1983 which is 0.004 for each story. The maximum mean drift of all buildings with various configurations under ELCENTRO earthquake are less than 0.004. The results obtained from 25 storey building show that, maximum mean drift is more than 0.004 in all shear wall configurations except sixth one. So, it is observed, although,those configurations is adequate for 10, 15, and 20 storey building, but when the number of story increasing those configuration may not satisfy the drift limitation. The sixth configuration results are acceptable for all models. The maximum drift is 0.0038 in 25 stories building which is less than 0.004. So the best shear wall position for

According to IS1893, the story drift in any story due to the minimum specified lateral load shall not exceed 0.004 times of story height. It means the maximum mean drift, which is defined as top story drift divided by height of the building shall not exceed 0.004. The maximum mean drift to number of story diagram is obtained for both earthquakes to do comparison between the values of maximum mean drift and code limitation. Also the equation of each trend line (based on the values of maximum mean drift correspond to the number of story) and corresponding correlation coefficients is given; the correlation coefficient indicates the accuracy of equation. The R square value is between zero (lowest accuracy) and one (highest accuracy). Hence the values Š 2012 ACEE DOI: 02.AETACE.2012.3.7

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Full Paper Proc. of Int. Conf. on Advances in Civil Engineering 2012 this building, considering its plan is the sixth configuration.

However, the values are more than those in other positions

in lower number of storey buildings but, it satisfied the limitation for all considering buildings.

Fig. 8. First shear wall configuration

Fig. 9. Second shear wall configuration

Fig. 10. Third shear wall configuration

Fig. 11. Fourth shear wall configuration

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Fig. 12. Fifth sear wall configuration

Fig. 13. Sixth shear wall configuration

CONCLUSIONS The study on the dynamic response of building with various shear wall configuration and their influence on seismic behavior of building is carried out and the top storey drift for those configurations are obtained. From the study, the following conclusions have been made.

1. Different position of shear walls can reduce the top story drift at least twice, which means the drift of building is reduced 100 percent from highest value to lowest one.

2. Maximum drift limitation of 0.004 as per IS code is satisfied for all height of the building using ELCENTRO earthquake, whereas the above limitation is not satisfied by TABAS earthquake.

3. For configuration sixth, the maximum drift limitation is satisfied by both ELCENTRO and TABAS earthquakes, this shows that, the location of shear walls plays major role for the limitation of drift.

4. The quantity of shear walls cannot guarantee the seismic behavior of buildings, which means, if you provide more shear walls, it will not guarantee the better seismic behavior of buildings.

[4]

[5]

[6]

[7]

[8]

REFERENCES [1] Najma Nainan, ‘’ Dynamic Response of Seismo-resistant Building Frames ‘’ International Journal of Engineering Science and Technology (IJEST), Vol. 4 No.05, pp. 1865-1870, May 2012.

[2] Mete. A. Sozen ‘’ Seismic Behavior of Reinforced Concrete Building ‘’ Chapter 13, CRC press LLC, 2004.

[3]

[9]

[10]

Sozen, M. A., ‘’ Earthquake Response of Buildings with [11]

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Robust Walls ‘’ Proceedings of Fifth Chilean Conference on Seismology and Earthquake Eng., Santiago, 1989.

Maximiliano ASTROZA, María Ofelia MORONI and Carlos SALINAS ‘’ Seismic Behavior Qualification Methodology For Confined Masonry Buildings ‘’ Proceedings of 12th World Conference on Earthquake Engineering (12WCEE), Auckland, N.Z, paper number 1123, 2000.

Young-Hun Oh, Sang-Whan Han, and Yeoh-Soo Choi, ‘’ Evaluation and Improvement of Deformation Capacities of Shear Walls Using Displacement-Based Seismic Design ‘’ International Journal of Concrete Structures and Materials Vol.18, No.1E, pp.55-61, June 2006.

R.K.L. Su, N.T.K. Lam, H.H. Tsang ‘’ Seismic Drift Demand and Capacity of Non-Seismically Designed Concrete Buildings In Hong Kong Journal Articles Refereed ‘’ Electronic Journal of Structural Engineering, Vol. 8, pp. 110-120, 2008.

Kenneth A. Gent Franch, Gian M. Giuliano Morbelli, Maximiliano A. Astroza Inostroza, Roberto E. Gori, ‘’ A seismic vulnerability index for confined masonry shear wall buildings and a relationship with the damage ‘’ Journal of engineering structure, 30, pp. 2605-2612, 2008.

B. Kameshwari, G. Elangovan, p. Sivabala, G. Vaisakh ‘’ Dynamic Response Of High Rise Structures Under The Influence Of Discrete Staggered Shear Walls ‘’ International journal of engineering science and technology, Vol 3, No 10, October 2011.

Elisa Lumantarna, Nelson Lam, Bidur Kafle, JohnWilson, ‘’ Displacement Controlled Behaviour of Asymmetrical Buildings ‘’ Australian Earthquake Engineering Society Conference, 2008.

IS: 1893 (Part 1), 2002, “Criteria for Earthquake Resistant Design of Structures – general provisions and buildings”, Bureau of Indian Standards, New Delhi.

Pacific Earthquake Engineering Research Center (PEER): NGA Database, http://peer.berkeley.edu/