seismic evaluation of tall unstiffened steel plate shear wall (spsw) systems with emphasis on reversal phenomenon in the higher mode pushover curve

This paper attempts to study the seismic behavior of tall unstiffened steel plate shear wall (spsw) systems with an emphasis on the higher-mode pushover analysis and to elaborate the relevant pushover curve. improved pushover analyses (ipas) including the modal pushover analysis (mpa) and the modified modal pushover analysis (mmpa) are used for the frames in which the higher-mode effects are substantially important. the conventional pushover analysis using the fema load distributions is also implemented. to achieve this goal, mid-rise (10 and 15-story) and high-rise (20 and 30-story) spsw systems are investigated. to consider a detailed behavior of spsws in analyses, a three-dimensional (3d) finite element modeling is used. an interesting result is obtained that the higher-mode pushover analysis results in a reversal in the pushover curve for all of the unstiffened spsw systems studied in this investigation that this phenomenon is rare in performance-based seismic engineering. the results provide evidence that among the above-mentioned pushover analyses, the mpa procedure is accurate enough for the seismic evaluation of tall spsw systems. furthermore, the mpa is computationally time efficient in comparison with the nonlinear response history analysis for this kind of structures with 3d finite element modeling in which there exist a large number of frame and shell elements.