Performance and damages of reinforced concrete buildings during the October 23 and November 9, 2011 Van, Turkey, earthquakes

In this paper, it aimed to investigate the performance and damages of reinforced concrete buildings during October 23 (Erciş) and November 9 (Edremit), 2011 Van earthquakes in Turkey. A total of 28,000 buildings are damaged or collapsed in the city center and surrounding villages after the Erciş earthquake. This number increased to 35,000 after the Edremit earthquake. Large proportion of non-engineering reinforced concrete buildings completely collapsed or were damaged heavily. Most of the reinforced concrete buildings in the affected area are not designed and constructed in accordance with Turkish Earthquake Resistant Design Code. The cracking and failure patterns of the reinforced concrete buildings are examined. Seismic code requirements are discussed and compared with observed details. It is seen that the damages are due to several reasons such as site effect, location, and length of the fault, the poor construction quality, the poor concrete strength quality and unribbed reinforcement steel, poor detailing in beam column joints, strong beam-weak columns, soft stories, weak stories, inadequate transverse reinforcement, existence of short lap splices and incorrect end hook angle, short columns, weak walls, inadequate safe distance between buildings, unconfined gable walls, concrete slab failures, insulation materials, broken staircase slab and cracks at the corners of the windows and doors. Also, it is emerged that 26% of the buildings have no building license, 66% of the buildings' ground floor is used as a shop, 36% of the buildings have no static project, building (static) projects of 57% of the structures are insufficient, 57% of the buildings are not constructed in accordance with their static project, 74% of the static projects have no detail drawings and hoops densifications, the majority of the buildings have not got sufficient compressive strength according to the related earthquake code, aggregate dimensions are larger than maximum aggregate diameter for concrete, 60% of the building was constructed using un-ribbed reinforcement steel, and the majority of the buildings (85%) have not got any soil report. In addition to these reasons, the two earthquakes hit the reinforced concrete buildings within 17 days, causing progressive damage.