Lessons Learned from Collapse of Zumrut Building under Gravity Loads

The 11-story reinforced concrete Zumrut Building in Konya, Turkey collapsed on February 2, 2004. Ninety-two people died. This study was conducted to determine the mechanism of the collapse and identify lessons learned to avoid future disasters. Using structural drawings, material samples, and soil information obtained from the site, reasons for the collapse were investigated. A three-dimensional (3-D) structural model and analyses were performed using ETABSV8.11, and various possible critical cases were studied. The step-wise nonlinear analysis used to obtain the collapse mechanisms was an example of forensic structural engineering and revealed that the progressive collapse of the building was torsional, caused by decrease in structural system’s capacity to redistribute gravity load after failure of a column. The lessons learned include the importance of project controls to reduce design and construction errors, ensure that construction and repairs are consistent with design intent, and changes are checked for safety and included in drawings. The importance of integrating architectural and structural systems to form 3-D continous structural frames to reduce the probability of progressive collapse is also discussed.