Radical changes in the seismic design philosophy based on 2023 Kahramanmaraş earthquakes observations in Türkiye

The two simultaneous earthquakes occurred in 2023 leading to over 50 000 casualties in more than 250 thousand collapsed and heavily damaged buildings in Türkiye. Despite modernizing the seismic code regularly, it has not been possible for Türkiye to mitigate the seismic risk. Two important and new observations were made in the aftermath of 2023 earthquakes: (i) Structural wall systems exhibited superior performance with no record of collapse. (ii) Several thousand buildings constructed after 2000 collapsed despite better seismic codes. This paper presents the background of the radical modifications for minimum structural wall amounts and maximum interstory drift ratio limits. First, the site observations for the performance of buildings with structural walls are presented. Based on seismic assessment of more than 30 000 existing building plans, the relationship between maximum interstory drift demand and wall-column area ratio is examined. The proposed limits are compared to the risk levels of existing buildings for validation.