PUSHOVER EVALUATION OF TALL BUILDING REINFORCED CONCRETE FRAMES

Abstract

Introduction to the nonlinear time history analysis including the main concepts and numerical analysis of nonlinear time history parameters are described. The damping of structures is illustrated. Characteristics of ground motions used in the analysis are presented. Ground motions records and response spectrum curves are plotted. Nonlinear time history analyses using five natural ground motions are performed for all parametric study buildings and comparisons of important responses of buildings are presented.

Comparisons between shear capacities determined by static pushover curves using the fixed Uniform and ELF load patterns as they give the upper and lower bounds of the capacities respectively and those determined by NL-THA are presented. The comparisons indicate that most of the results of the nonlinear time-history analyses lie within the upper- and lower-bound pushover curves using fixed lateral load patterns. A few results are scattered outside these two bounding pushover curves in both the linear and nonlinear ranges. Additionally, some of the nonlinear time-history results lie outside the upper-bound pushover curves and this may indicate that the NL-THA less conservative.

Comparisons between interstory drifts determined by pushover analysis and those determined by NL-THA are presentedand it is noted that Mode1 and ELF under estimate the interstory drift ratio at lower stories and the top story and overestimate the drift ratio at middle stories, SRSS load pattern underestimate the drift ratio at lower stories and overestimate the drift ratio at upper stories.