Collapse of a reinforced concrete building with insufficient diaphragm and discussion on diaphragm strengthening for avoiding such failures

Structural integrity is one of the key issues during the design of a proper lateral force resisting system for structures (i.e. against seismic actions). Therefore, proper design and construction of diaphragms are extremely critical if “rigid diaphragm” assumption is made during structural analyses. Seismic events show that insufficient diaphragms, failing to transfer seismic forces properly to vertical structural members as foreseen during design, are among the reasons causing collapse of buildings. In this paper, observations on a 17-story reinforced concrete (RC) building that lost its integrity and collapsed mainly due to insufficient diaphragm action during the 2023 Turkey Earthquakes, are presented. Furthermore, approach for strengthening of the diaphragm that could have avoided the total collapse of the building is discussed.