Improved estimation of time-varying mean displacement and parametric study of biaxial effect on inelastic responses of high-rise buildings to wind

Abstract

Three reduced-order building models with different biaxial hysteretic generalized restoring force and displacement relations were developed using static modal pushover analysis of a nonlinear finite element model of a 60-story steel building. It was illustrated that the reduced-order models can give accurate estimations of fluctuating responses but overestimate the time-varying mean alongwind displacement. The nonphysical displacement drift of the Bouc-Wen hysteresis model is responsible for this overestimation. An improved estimation of time-varying mean alongwind displacement was presented. A comprehensive parametric study concerning the influence of biaxial interaction on inelastic responses was also performed. The biaxial interaction leads to faster growth of time-varying mean displacement but does not affect its steady-state value. It results in increase in the low-frequency component but decrease in the resonant component of alongwind displacement. It leads to more reduction in alongwind acceleration. The crosswind response, which is greater than the alongwind response, is not affected, or only slightly reduced when both alongwind and crosswind responses are close to each other in magnitude. The peak ductility demand of a combined alongwind and crosswind response is less affected by the biaxial interaction. The new insights of this study can have wide applications to other buildings and wind directions.