Assessing the Impact of Ground Motion Duration on Losses in Typical Modern Steel Moment Frames

Abstract

This research was undertaken to study the duration effects on the seismic economic risk of steel moment frame (SMF) buildings, a prominent class of buildings in commercial stock. Firstly, a modified version of FEMA P-695 ground motion scaling, tailored for seismic loss estimation purposes and incorporating two sets of spectrally matched bi-directional short- and long-duration ground motions, is proposed to study code-compliant plan-symmetrical SMFs with different heights (i.e., two to 20 stories). It is shown that long-duration ground motions increase the collapse risk of SMFs, on average, by 28.0% at the MCE level. Next, a component-based loss estimation methodology was adopted for evaluating the seismic losses under each set of ground motions. These losses are studied separately for building components (i.e., structural and nonstructural) and contents. Moreover, we propose an approach for calculating average annualized loss (AAL) as a prominent risk meter that segregates contributions of short- and long-duration ground motions to attain hazard consistency. Loss analyses showed the minimal impact of building height on the contribution of these two types of earthquakes. The seismic risk analysis of buildings also revealed that collapse risk is influenced mainly by duration effects followed by building and content losses.