Assessment of Nonlinear Static Analyses on Irregular Building Structures

Abstract

Nonlinear static analysis is many times chosen, in engineering practice, to predict the seismic demands in building structures. Despite its simplicity, the nonlinear static analysis based on invariant load patterns has certain limitations caused by its inability to account for the variation of the dynamic characteristics, of the building structure, resulting from inelastic behavior and the higher modes effect. The paper presents a comparative study on three building structures, for which were made adaptive and nonadaptive nonlinear static analyses and incremental nonlinear time history analyses were performed. The analyzed buildings structures have elevation irregularity, except for the smallest which is regular. The capacity curves, resulting from nonlinear static analyses were compared with the mean capacity curve resulting from incremental nonlinear time-history analyses. The study has shown that the adaptive nonlinear static analysis, with displacements load pattern, caught, with enough accuracy, the behavior of irregular building structures of low and medium height. The nonlinear static analyses may not sufficiently predict the seismic demand for the tallest building structure, having deep elevation irregularity.