Ground motion sensitivity of a Vancouver-style high rise

Abstract

The purpose of the study discussed in this paper is to evaluate the seismic response of a modern building, designed according to the current building code and to extreme earthquake earthquakes from two different source mechanisms. To this end, a three-dimensional nonlinear dynamic response of a reinforced concrete high-rise building, typical of the type built in Vancouver, British Columbia, is investigated. According to current design practice, the building has been designed to resist lateral loads with a coupled shearwall system. A comparison of the responses of the building to crustal and subduction type earthquakes of similar magnitudes is presented and discussed. The ground motion records selected for this study were derived from recorded crustal and subduction events, which are both considered to be extreme, and beyond the code-based design requirements of the building. A part of this study includes an evaluation of how the dynamic properties of the building change as the building is being damaged by severe ground shaking. The results of the study show that the crustal earthquake imposes large upper levels displacements, and much plastic hinging near the base because the response of the building is governed mainly by the first mode of the "undamaged" system. The subduction earthquake results in displacements smaller than those from the crustal event and causes plastic hinging at mid-height and near the base as well as large torsional rotations, because the behaviour of the building is greatly influenced by the second mode of the "damaged" system.Key words: nonlinear dynamic analysis, seismic, high rise, reinforced concrete, coupled shearwall.