Analysis of a multi-story reinforced concrete residential building damaged under its self-weight

Reinforced concrete framed residential buildings are remarkably common in Turkey. Observations after recent earthquakes revealed that a great portion of the present building stock has inadequate seismic resistance. Moreover, collapses of several multi-story reinforced concrete buildings under their self-weight have also been observed despite any dynamic activity. The tragic example of the collapse of the "Zumrut" residential building under its self-weight in 2004 and the death of its 93 occupants have highlighted the need to re-examine the structural safety of existing buildings throughout the country. In this study, a multi-story reinforced concrete building located in the same city where the Zumrut disaster occurred, has been investigated. The damage occurred under its self-weight and their causes have been studied in detail. Four columns located in the basement of this nine-story reinforced concrete building have suddenly started to crack and fracture. At this stage, the authors were invited to the building for investigation during which initiation of another column failure was observed. After securing the building, concrete test samples were taken from each floor. The building is then modeled in 3D using a finite element software. A series of analyses have been carried out based on some reasonable assumptions. The demand-to-capacity ratios for each structural member were determined and a vertical incremental nonlinear pushover analysis was performed so that the possible failure mechanisms could be determined. The results indicated that the limited reserve capacity of columns and variation in material properties led to the observed failure.