Building damages during the September 19, 2017 earthquake in Mexico City and seismic retrofitting of existing first soft-story buildings

Abstract

A strong earthquake (Mw = 7.1) hit Mexico City at 13:14 local time on September 19, 2017. The earthquake severely damaged more than 600 buildings and more than 1000 buildings were classified in different risk levels. First soft-story buildings were one of the most commonly used structural configurations in collapsed buildings. The very close location of seismic stations to the damage area provided the opportunity to assess the seismic response of the buildings subjected to real ground motions. This study aims to analyze the seismic damages observed during the visual inspection of the affected area, to evaluate the seismic vulnerability of typical soft-story structures, and to propose retrofit alternatives that include braces and energy dissipation systems to enhance the seismic capacity of existing buildings. Results show that viscous dampers and elastoplastic devices are suitable alternatives to reduce the seismic vulnerability of existing low rise soft-story buildings. As the number of stories of the buildings increase, the combination of braces in one bay and elastoplastic dissipators in the other showed to be a feasible retrofit alternative as well.