On the Seismic Behavior of Unsymmetric-plan Tall Reinforced Concrete (RC) Buildings with Dual Wall-Frame System

This paper studies seismic evaluation of unsymmetric-plan tall reinforced concrete (RC) buildings with a dual wall-frame system, in which the effect of higher modes in plan and height is important. In this paper, one unsymmetric-plane reinforced concrete building of 18-story height was studied. Shear walls were replaced with an equivalent beam-column and their nonlinear behavior was considered with the interaction point hinges (PMM) and fiber elements. The seismic responses of the buildings were computed by nonlinear response history analysis (NL-RHA), advanced pushover analyses including the modal pushover analysis (MPA), the consecutive modal pushover (CMP), the upper bound pushover analysis (UB) and the extended N2 method (EN2) and a conventional pushover analysis with fundamental mode force distribution considering the two nonlinear behavior for the shear walls mentioned above. The results show that floor displacements are slightly influenced by the shear wall nonlinear model in comparison with the story drifts and plastic hinge rotations. Errors resulting from interaction point hinge (PMM) are almost larger than those from the fiber element. Also, the results indicate that the advanced pushover analyses can evaluate the seismic demands accurately in unsymmetric-plane tall buildings; The EN2 method gives a larger error compared with the other advanced methods, especially in estimating plastic hinge rotations.