Proposed methodology for building‐specific earthquake loss assessment including column residual axial shortening

This paper proposes methodological developments for quantifying the impact of residual axial shortening of first‐story steel columns on earthquake loss estimations in steel moment‐resisting frame (MRF) buildings. A new formulation is proposed that accounts for the likelihood of having to demolish a steel MRF building due to column residual axial deformations in addition to residual story‐drift ratios. The formulation is informed by means of data from a comprehensive survey conducted worldwide to assess the likelihood of steel column repairability due to residual axial shortening. A practical method for quantifying column axial‐shortening in parameterized system‐level numerical simulations is presented. The proposed approach is illustrated by conducting economic seismic loss estimations in two case‐study steel MRF buildings designed in urban California according to the current seismic design practice. It is found that when the ground‐motion duration is appreciable, the examined steel MRFs are more prone to column axial‐shortening than residual story‐drifts at moderate to high seismic intensities. The results suggest that economic losses due to demolition may be underestimated if column residual axial‐shortening is neglected from loss estimations. Limitations as well as directions for future research are discussed