Abstract
Pushover analysis has become one of the most commonly used nonlinear static procedures (NSP) for the seismic estimation of structures in engineering practice. In this paper, a new lateral load pattern is presented to enhance the accuracy of conventional pushover analysis (CPA) procedures for evaluating seismic behaviors of asymmetric-plan multistory buildings, which has considered the effect of torsion and higher modes. This spatially distributed lateral load pattern is proposed eventually by introducing and calculating the coefficients of adjustment and distribution respectively. The performance and accuracy of the proposed spatial pushover analysis (SPA) procedure is verified against two distinct multistory buildings with irregular plans subjected to five medium-to-strong ground motions. Furthermore, the peak responses in terms of base shear, roof displacements, interstory drifts, plastic hinge rotations and pushover capacity curves obtained from the SPA method are compared with those from nonlinear time history analyses (NTHA), and CPA procedures. The comparative results indicate that new lateral load pattern agrees very well with the NTHA procedure. The proposed SPA procedure shows its efficiency and overcomes the limitations of current extended pushover methods to assess the seismic responses of asymmetric-plan structures. It is strongly suggested that the new load pattern as an applicable method for pushover analysis of asymmetric-plan structures.
Highlights
Pushover analysis has been extensively used as a simplified tool for estimating seismic behaviors of virtually every type of building
Results obtained from the spatial pushover analysis (SPA) procedure are initially compared with nonlinear static procedures (NSP) recommended by Federal Emergency Management Agency (FEMA)-356 [21] which are considered as conventional lateral load patterns
The proposed SPA procedure is based on the characteristics of the lateral load distribution for the asymmetric structural type and this method accounts for the torsion effect due to eccentricity
Summary
Pushover analysis has been extensively used as a simplified tool for estimating seismic behaviors of virtually every type of building. Reasonable selection of lateral load pattern is more significant than the determination of target displacement during pushover analysis. Despite of extensive applications in practical engineering, the CPA procedures are unable to estimate the general responses of high-rise asymmetric-plan structures due to ignoring the effect of higher modes and torsion. Such above-mentioned load patterns may produce unacceptable misleading results when applied in tall buildings with irregular plans. The seismic responses of asymmetric-plan structures are influenced by the principal factor, coupled translational-torsional effect. It is essential to retrofit and extend an appropriate pushover analysis method for asymmetric-plan structures currently
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