Seismic performance assessment of weak first-storey RC buildings designed with old and new seismic provisions for Mexico City

•WFS buildings designed with NTCS-1976 have premature loss of lateral strength capacity.•Buildings designed with NTCS-1976 are prone to develop a weak first-storey mechanism.•New approach of the NTCS-2017 avoids first-storey drift concentration along the height.•WFS buildings designed with NTCS-2017 might still exceed seems to limit first-storey drifts below 0.6%. This paper presents the main results of an investigation focused on evaluating the new seismic design requirements for weak first-story reinforced concrete (RC) buildings prescribed in the 2017 edition of the Technical Norms for Seismic Design (NTCS-2017) for Mexico City. To provide a context, the seismic response of a family of low-to-medium height buildings designed with the updated NTCS-2017 was compared with that of counterpart’s buildings designed with the 1976 old edition of the NTCS (NTCS-1976). All building models where subjected to a set of earthquake ground motions recorded at the transition and soft soil sites during the recent strong intermediate-depth intraslab September 19, 2017 (Mw = 7.1) Puebla-Morelos earthquake, which caused significant structural damage to this type of buildings. Results from this investigation revealed that the requirements for weak first-storey RC buildings change the distribution of peak interstorey drift, IDR, along height, which avoids a concentration of IDR at the first-story. In addition, they delay the formation of a weak first-storey mechanism. This study also exhibited that weak first-storey RC buildings designed with old seismic provisions are susceptible to experience moderate-to-severe structural damage under strong normal-faulting intraslab earthquakes, which is consistent with field reconnaissance of damaged buildings after the September 19, 2017 (Mw = 7.1) Puebla-Morelos earthquake.