Seismic Inelastic Response of R/C Frames with Vertical Irregularities

T. Branci(1*)

(1) Department of Civil Engineering, Faculty of Civil Engineering and Architectural, Hassiba Benbouali, University of Chlef, Algeria
(*) Corresponding author

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This paper presents the inelastic seismic response of multistory reinforced concrete (R/C) frame structures with irregularities in elevation. Five twelve-story frame structures with different degrees of irregularity in elevation were selected and their responses were compared with the ones of a corresponding regular structure. Three cases of vertical irregularities have been considered: 1) frames with single setback, 2) stepped frame, and 3) frame having a soft first story. The frames have been designed to the provisions of Eurocode 2 (EC2) and Eurocode 8 (EC8) for the medium ductility class (DCM) and common peak ground acceleration and material characteristics. All frames have been subjected to inelastic dynamic time-history analysis, due to an ensemble of seven ground motions. The effects of these irregularities on the seismic responses of the frames were compared and discussed. The comparisons revealed that frames having vertical irregularities show significantly high demand for ductility, peak displacement and inter-story drift for columns and beams at soft first story and setback story level when compared to regular frame. Abrupt changes in shears are experienced near the levels of the setbacks.
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Frame; Inelastic; Irregular; Response; Seismic

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European Standard EN 1998-3-2005, Eurocode 8: Design of Structures for Earthquake Resistance, Part 1: General Rules, Seismic Actions and Rules for Buildings (NF EN 1998-1, 2005).

J. L. Humar, E. W. Wright, Earthquake Response of Steel-Framed Multistory Buildings with Set-Backs, Earthquake Engineering and Structural Dynamics, Vol. 5(Issue 1): 15-39, January 1977.

G. R. Aranda, Ductility Demands for R/C Frames Irregular in Elevation, Proceedings of the Eighth World Conference on Earthquake Engineering, Vol. 4, pp. 559-566, San Francisco, July 1984.

J. P. Moehle, L. F. Alarcon, Seismic Analysis Methods for Irregular Buildings, Journal of Structural Engineering, ASCE, Vol. 112 (Issue 1): 35-52, January 1986.

S. L. Wood, Seismic Response of R/C Frames With Irregular Profiles, Journal of Structural Engineering, ASCE, Vol. 118, (Issue 2): 545-566, 1992.

C. M. Wong, W. K. Tso, Seismic Loading For Buildings with Setbacks, Canadian Journal of Civil Engineering, Vol. 21 (Issue 5): 863-871, February 1994.

A. A. K. Al-Ali, H. Krawinkler, Effects of Vertical Irregularities on Seismic Behavior of Building Structures, Report No. 130, The John A. Blume Earthquake Engineering Center, Dept. Civil and Environmental Eng., Stanford Univ., Stanford, U.S.A, 1998.

S. Das, J. M. Nau, Seismic Design Aspects of Vertically Irregular Reinforced Concrete Buildings, Earthquake Spectra, Vol. 19 (Issue 3): 455-477, August 2003.

C. Athanassiadou, S. Bervanakis, Seismic behavior of R/C buildings with setbacks designed to eurocode 8, Proceedings of the 4th Europeen Worshop on the Seismic Behavior of Irregular and Complex Structures, pp. 26-27, Thessaloniki, Greece, August 2005.

M. Fragiadakis, D. Vamvatsikos, M. Papadrakakis, Evaluation of the Influence of Vertical Irregularities on the Seismic Performance of a Nine-Storey Steel Frame, Earthquake Engineering and Structural Dynamics, Vol. 35(Issue 12): 1489-1509, 2006.

C. J. Athanassiadou, Seismic Performance of R/C Plane Frames Irregular in Elevation, Engineering Structures, Elsevier, Vol. 30, 1250–1261, 2008.

P. Sarkar, P. A. Meher, D. Menon, Vertical Geometric Irregularity in Stepped Building Frames, Engineering Structures, Elsevier, Vol. 32 (Issue 8):2175-2182, 2010.

International Code Council, International Building Code 2003, Falls Church, Va, 2003.

V. K. Sadashiva, G. A. MacRae, B. L. Deam, Building regularity provisions for seismic design of structures, 14th European Conference on Earthquake Engineering (ECEE), Ohrid, Republic of Macedonia, 30.08-03.09, 2010.

A. E. Kanaan, G. H. Powell, DRAIN-2D, A General Purpose Computer Program for Inelastic Dynamic Response of Plane Structures, Report No. EERC 73-6, Earthquake Engineering Research Center, University of California, Berkeley, 1973.

PEER, Pacific Earthquake Engineering Research Centre. Strong Ground Motion Database., 2006

A. Habibullah, SAP 2000, Static and Dynamic Finite Element Analysis of Structures, Computers and Structures Inc. Berkeley, California, 2007.


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