Evaluation of the modal pushover analysis procedure using vertically 'regular' and irregular generic frames

The recently developed modal pushover analysis (MPA) for estimating seismic demands on buildings has been shown to be a significant improvement over the pushover analysis procedures currently used in structural engineering practice. The results presented in this thesis evaluate the accuracy of MPA for a wide range of frame buildings with strong-columns and weak-beams and a ground motion ensemble.; Investigated first is the basic premise that the roof displacement of a multistory building can be determined from the deformation of an SDF system. The modal pushover analysis procedure has the advantage of reducing the dispersion in the roof displacement and the underestimation of the median roof displacement for elastic or nearly elastic cases at the expense of increasing slightly the overestimate of roof displacement of buildings responding far into the inelastic range.; This study also compares the seismic demands for vertically irregular and “regular” frames determined by rigorous nonlinear RHA. The effects of vertical irregularity on the median values of story drifts and floor displacements are documented with the following results: (1) the three types of irregularities similarly influence the heightwise variation of story drifts, with the effects of strength irregularity being larger than stiffness irregularity, and the effects of combined-stiffness-and-strength irregularity being the largest among the three; (2) introducing a soft and/or weak story increases the story drift demands in the modified and neighboring stories and decreases the drift demands in other stories; (3) on the other hand, a stiff and/or strong story decreases the drift demand in the modified and neighboring stories and increases the drift demands in other stories; (4) drift demands in the upper stories are much more sensitive to irregularities in the lower stories than the response of lower stories is affected by irregularities in the upper stories; (5) while the roof displacement is usually insensitive to vertical irregularity, it is significantly different for frames that are stiffness-and-strength irregular in their lower half; and (6) irregularity in the base story or lower stories has significant influence on the heightwise distribution of floor displacements. (Abstract shortened by UMI.)...