Performance of the built environment in Mexico City during the September 19, 2017 Earthquake

Abstract

The September 19, 2017 earthquake (Mw = 7.1) was the most damaging earthquake that stroke Mexico City since the September 19, 1985 earthquake. However, taking aside the southeast region of Mexico City, where very strong ground motions were recorded, in the central region for the city, spectral accelerations were more than well-covered by the design spectra of Mexico City building codes since 1987. In this paper, and based upon a detailed inventory of 2458 damaged structures, the observed structural damage is discussed from several angles, in particular, the relationships of observed damage with: a) use for the structure, b) structural systems, c) number of stories, d) plan geometries and conditions of structural irregularity, e) conditions which increases the seismic vulnerability, and f) seismic codes, spectral accelerations and global ductility demands assessed from recorded ground motions. Although it can be concluded that total number of structural collapses and severe damage was smaller for buildings designed according to the collapse-prevention design philosophy in Mexico City (802) in comparison to former older codes (967), this total number is not acceptable from an engineering, social and economical viewpoints. In the opinion of the authors, engineers should start thinking seriously on moving towards resilient-based seismic design strategies to reduce such large extent of damage in modern, newly constructed buildings in very active seismic zones such as Mexico City.