Seismic evaluation of geometrically irregular steel moment resisting frames with setbacks considering their dynamic characteristics

A setback building has a sudden discontinuity in the frame geometry along the height. This kind of irregularity causes an abrupt discontinuity in stiffness, strength and mass of the building frame. In this study, a total of nineteen mid-rise 9-story steel moment resisting frames with setbacks including the broad range of different geometrical configurations were studied. An eigenvalue analysis was performed to evaluate and scrutinize the dynamic characteristics of setback structures. The effect of geometrical configurations on the seismic responses of setback frames was studied by means of nonlinear response history analysis using a set of far-field ground motion records. Moreover, due to the rapidly increasing use of pushover analysis for the seismic evaluation of structures in recent years, enhanced pushover analyses (EPAs) including the modal pushover analysis, the upper bound pushover analysis, the consecutive modal pushover and the extended N2 methods were implemented as a main part of this study. The findings show that two factors including the location of setback and the degree of setback are of key importance and influence the dynamic characteristics and seismic responses of setback structures. The degree of accuracy of the enhanced pushover analysis methods generally depends on the dynamic characteristics (geometrical configuration) of the setback frames. The largest error in the EPAs in predicting the story drifts generally occurs in a setback frame with a larger amount of the ratio between the effective modal participating mass ratio of the higher modes and that of the first mode.

[1]  Rui Pinho,et al.  ADVANTAGES AND LIMITATIONS OF ADAPTIVE AND NON-ADAPTIVE FORCE-BASED PUSHOVER PROCEDURES , 2004 .

[2]  Pradip Sarkar,et al.  Vertical geometric irregularity in stepped building frames , 2010 .

[3]  Toshimi Kabeyasawa,et al.  A story shear-based adaptive pushover procedure for estimating seismic demands of buildings , 2010 .

[4]  Ming Wei Liu,et al.  An upper-bound pushover analysis procedure for estimating the seismic demands of high-rise buildings , 2004 .

[5]  Theodore L. Karavasilis,et al.  Seismic response of plane steel MRF with setbacks: Estimation of inelastic deformation demands , 2008 .

[6]  Faramarz Khoshnoudian,et al.  A consecutive modal pushover procedure for estimating the seismic demands of tall buildings , 2009 .

[7]  Wai-Fah Chen,et al.  Earthquake Engineering for Structural Design , 2005 .

[8]  Anil K. Chopra,et al.  Evaluation of a Modified MPA Procedure Assuming Higher Modes as Elastic to Estimate Seismic Demands , 2004 .

[9]  Helmut Krawinkler,et al.  PROS AND CONS OF A PUSHOVER ANALYSIS OF SEISMIC PERFORMANCE EVALUATION , 1998 .

[10]  Anil K. Chopra,et al.  A modal pushover analysis procedure for estimating seismic demands for buildings , 2002 .

[11]  Lili Xie,et al.  An improved modal pushover analysis procedure for estimating seismic demands of structures , 2008 .

[12]  M. Selim Günay,et al.  Generalized force vectors for multi‐mode pushover analysis , 2011 .

[13]  Rui Pinho,et al.  DEVELOPMENT AND VERIFICATION OF A DISPLACEMENT-BASED ADAPTIVE PUSHOVER PROCEDURE , 2004 .

[14]  Jack P. Moehle,et al.  Seismic Response and Design of Setback Buildings , 1990 .

[15]  A. Davoudi,et al.  An adaptive pushover procedure based on effective modal mass combination rule , 2013 .

[16]  P. Fajfar,et al.  A Nonlinear Analysis Method for Performance Based Seismic Design , 2001 .

[17]  J. L. Humar,et al.  Earthquake response of steel‐framed multistorey buildings with set‐backs , 1977 .

[18]  Arturo Tena-Colunga.  Evaluation of the seismic response of slender, setback RC moment-resisting frame buildings designed , 2004 .

[19]  C. J. Athanassiadou.  Seismic performance of R/C plane frames irregular in elevation , 2008 .

[20]  Anil K. Chopra,et al.  SEISMIC RESPONSE OF VERTICALLY IRREGULAR FRAMES: RESPONSE HISTORY AND MODAL PUSHOVER ANALYSES , 2004 .

[21]  Yahya C. Kurama,et al.  An alternative pushover analysis procedure to estimate seismic displacement demands , 2008 .

[22]  Hsiao-Hui Hung,et al.  An Alternative Pushover Analysis Procedure to Estimate Seismic Displacement Demands for Irregular Bridges , 2012 .

[23]  Moosa Ebrahimi Nezhad,et al.  Seismic evaluation of vertically irregular building frames with stiffness, strength, combined-stiffness-and-strength and mass irregularities , 2015 .

[24]  Phaiboon Panyakapo,et al.  Cyclic Pushover Analysis procedure to estimate seismic demands for buildings , 2014 .

[25]  Jack P. Moehle,et al.  Seismic analysis, design, and review for tall buildings , 2007 .

[26]  Mehdi Poursha,et al.  The modified and extended upper-bound (UB) pushover method for the multi-mode pushover analysis of unsymmetric-plan tall buildings , 2015 .

[27]  K. Isman.  High Rise Buildings , 2017 .

[28]  Sashi K. Kunnath,et al.  Adaptive Modal Combination Procedure for Nonlinear Static Analysis of Building Structures , 2006 .

[29]  W. K. Tso,et al.  Seismic loading for buildings with setbacks , 1994 .

[30]  Devesh P. Soni,et al.  Qualitative review of seismic response of vertically irregular building frames , 2006 .

[31]  Rui Pinho,et al.  Verification of displacement-based adaptive pushover through multi-ground motion incremental dynamic analyses , 2009 .

[32]  Mehdi Poursha,et al.  A single-run multi-mode pushover analysis to account for the effect of higher modes in estimating the seismic demands of tall buildings , 2015, Bulletin of Earthquake Engineering.

[33]  Federico M. Mazzolani,et al.  Theory and Design of Seismic Resistant Steel Frames , 1996 .

[34]  Peter Fajfar,et al.  The extended N2 method taking into account higher mode effects in elevation , 2011 .