Estimation of Seismic Deformation Demands of Tall Buildings with Symmetric Setbacks

Authors: A. Alirezaei, S. Vahdani

Abstract:

This study estimates the seismic demands of tall buildings with central symmetric setbacks by using nonlinear time history analysis. Three setback structures, all 60-story high with setback in three levels, are used for evaluation. The effects of irregularities occurred by setback are evaluated by determination of global-drift, story-displacement and story drift. Story-displacement is modified by roof displacement and first story displacement and story drift is modified by global drift. All results are calculated at the center of mass and in x and y direction. Also the absolute values of these quantities are determined. The results show that increasing of vertical irregularities increases the global drift of the structure and enlarges the deformations in the height of the structure. It is also observed that the effects of geometry irregularity in the seismic deformations of setback structures are higher than those of mass irregularity.

Keywords: Deformation demand, drift, setback, tall building.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1100010

References:

[1] O. A. Pekau, and R. Green, “Inelastic structures with setbacks,” in Proc. 5th World Conference on Earthquake Engineering, Italy, 1974, vol. 2.
[2] J. L. Humar, and E. W. Wright, “Earthquake response of steel-framed multistorey buildings with setbacks,” Earthquake Engineering and Structural Dynamics, vol. 5, 1977.
[3] G, R. Aranda, “Ductility demands for R/C frames irregular in elevation,” in Proc. 8th World Conference on Earthquake Engineering, San Francisico, 1974, vol. 4.
[4] B. M. Shahrooz, and J. P. Moehle, “Seismic response and design of setback buildings,” Journal of Structural Engineering, vol. 116, no. 5, pp. 1423-1439, May. 1990.
[5] A. A. K. Al-Ali, and H. Krawinkler, “Effects of vertical irregularities on seismic behavior of building structures,” John A. Blume Earthquake Engineering Center, Stanford University, Stanford, Rep. No. 130, 1998
[6] C. Chintanapakdee and A. K. Chopra, “Seismic response of vertically irregular frames: response history and modal pushover analysis,” Journal of Structural Engineering, vol. 130, no. 8, pp. 1177-1185 January. 2004.
[7] S. L. Wood, “Dynamic response of R/C Frames with irregular profiles,” in Proc. 3rd U.S. National Conference on Earthquake Engineering, August. 1986.
[8] C. M. Wong, and W. K. Tso, “Seismic loading for buildings with setbacks,” Canadian Journal of Civil Engineering, vol. 21, no. 5, October. 1994.
[9] D. Pinto, and A. G. Costa, “Influence of vertical irregularities on seismic response of buildings,” in Proc. 10th European Conference on Earthquake Engineering, Rotterdam, 1995, vol. 2.
[10] X. N. Duan , and A. M. Chandler, “Seismic torsional response and design procedures for a class of setback frame buildings,” Earthquake Engineering and Structural Dynamics, vol. 24, no. 5, pp. 761–777, 1995
[11] E. G. Valmundsson, and J. M. Nau, “Seismic response of building frames with vertical structural irregularities”, Journal of Structural Engineering, vol. 123, no. 1, January. 1997.
[12] M. Fragiadakis, D. Vamvatsikos and 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, no. 12, pp. 1489–1509, 2006
[13] T. L. Karavasilis, N. Bazeos, D. E. Beskos, “Estimation of seismic inelastic deformation demands in plane steel MRF with vertical mass irregularities,” Engineering Structure, vol. 30, no. 11, pp. 3265–3275, 2008
[14] American Society of Civil Engineers, ASCE/SEI 7-10 “Minimum design loads for buildings and other structures”. Reston, VA. 2010.
[15] G. D. P. K. Seneviratna, and H. Krawinkler, “Evaluation of inelastic MDOF effects for seismic design,” John A. Blume Earthquake Engineering Center, Stanford University, Stanford, Rep. No. 120, 1997
[16] A. Alirezaei, S. Vahdani, “Seismic response of tall building with setback,” unpublished.
[17] American Society of Civil Engineers, ASCE/SEI 41-06 “Seismic Rehabilitation of Existing Buildings”. Reston, VA. 2007.
[18] Federal Emergency Management Agency, FEMA P695 “Quantification of Building Seismic Performance Factors”. Washington, D.C. 2008.