The September 19, 2017 earthquake (Mw = 7.1) struck M & eacute;xico between the states of Puebla and Morelos. The ground motion damaged buildings near the epicenter and in Mexico City, with 44 collapsed buildings and many more experiencing some level of damage. The study gathers and statistically analyzes all available information, identifying characteristics in the plan and elevation of the damaged structures. The analysis identified structural issues typically associated with damage, such as buildings with soft or flexible ground floors and corner buildings supported by reinforced concrete frames. Corner buildings often have infill walls on two sides adjacent to neighboring properties, which, when connected to columns, cause significant torsional effects. The corner effect, combined with other structural pathologies such as soft-story, irregular building shapes, and seismic amplification effects in some city regions, significantly contributed to the damage and building collapses presented during the earthquake. The results, in addition to showing damage statistics for buildings located in a corner with infill walls, showed that the facade walls in the corner provide very little lateral stiffness comparatively to the stiffness of the perimeter walls situated on the other two sides of the building, which causes significant torsion in the building. The study also revealed that corner buildings with infill walls next to low-rise buildings were significantly more at risk than those surrounded by buildings of similar heights. A non-linear analysis of a case study showed that the observed earthquake damages in corner buildings were indeed expected, given the building's seismic demands obtained with the numerical model.

The April 2010 earthquake (Mw = 7.2), which occurred about 40 km to the southeast of the city of Mexicali, Mexico, caused significant damage to buildings. To improve knowledge of the seismic response of the soil due to the occurrence of earthquakes, a response spectrum at 5% damping was calculated. A comparison between the spectral ordinates obtained in this study and the spectra proposed by the regulations of the Federal Electricity Commission (CFE for its acronym in Spanish) in its seismic design for civil works manual, which is currently used as the design standard throughout the country, was made. We calculated response spectra using records from the April 2010 earthquake and a stratigraphic profile of the city to calculate a transfer function. We first corrected the records for site effect due to stations being over sedimentary soil, and then used them as Green functions to perform a numerical simulation of propagation through the stratigraphic profile to obtain a simulated surface record from which response spectra were calculated. Additionally, ambient seismic noise was measured at the same site to get the dominant period (To). We observed that the transfer function was similar to the spectral quotient up to 5 Hz and that To calculated in both ways gave similar values. The comparison suggests that the design spectrum of the CFE regulation can be considered as a representative spectrum for Mexicali for periods greater than 1.3 s, but not for the zone of short periods.

Seismic-resistant design incorporates measures to ensure that structures perform adequately under specific limit states, focusing on seismic forces derived from both the equivalent static and spectral modal methods. This study examined buildings on slopes in densely built urban areas, a common scenario in Latin American cities with high seismic risks. The adjustment of high-rise buildings to sloping terrains induces structural asymmetry, leading to plan and elevation irregularities that significantly impact their seismic response. This paper explores the asymmetry in medium-height reinforced concrete frame buildings on variable inclines (0 degrees, 15 degrees, 30 degrees, and 45 degrees) and its effect on their nonlinear response, assessed via displacements, rotations, and damage. Synthetic accelerograms matched with Chile's high seismic hazard design spectrum, scaled for different performance states and seismic records from the Chilean subduction zone, were applied. The findings highlight structural asymmetry's role in influencing nonlinear response parameters such as ductility, transient interstory drifts, and roof rotations, and uncover element demand distributions surpassing conventional analysis and in earthquake-resistant design expectations.