First-storey height effects on the collapse performance of buildings in extreme events

Abstract

Higher first-storey height could cause soft-storey irregularity due to less lateral stiffness, in which the hysteric energy dissipation is localized at the first storey of buildings. In the seismic design codes, two different approaches, based on the drift and lateral stiffness ratios, are used to determine soft-storey irregularity. In this study, four reinforced concrete models with different first-storey to typical-storey height ratios are used to show the first-storey height effects. It is shown that even if the models are regular for soft stories based on the seismic design code limits, the higher first storey considerably decreases the ductility capacity. Also, it is demonstrated that the ductility capacity is highly correlated with the storey height ratio. Although all models meet the design criteria of the Turkish Buildings and Earthquake Code (TBEC-2018), the results of the nonlinear time historey analysis reveal that the first-storey drift ratio considerably increases with the higher first-storey height. Further, the collapse performance of the four models is determined using the FEMA P695 procedure, and the results demonstrate that the collapse probability of the model with the highest first-storey height is over the ASCE 7-22 limit.