Earthquakes cause a high risk in reinforced concrete (RC) structures with respect to life and property loss. As a result of the earthquake occurred on October 23, 2011, and November 9, 2011, in Van, a large-scale loss of life and property has been observed. A lot of constructive problems were determined after the examinations of demolished or damaged buildings. One of the most important reasons of damage is that concrete strength is much lower than the expected one. The main purpose of this study is to examine the effect of the concrete strength of the demolished or damaged RC buildings on the performance of buildings. For this purpose, various concrete strengths have been selected among the reports which were prepared after the earthquake. In this manner, structural performances of three story buildings with three bays which have various concrete strengths are compared. The damage-limitation limit states are re-calculated with cross-sectional analysis program. Then, static pushover analysis is performed and thereby modal capacity curve is obtained and the target displacement is calculated. In addition to this, damages occurred in the cross sections are examined. National and international specifications such as ATC 40 and TEC-2007 are used in the numerical analyzes and evaluations. According to the obtained numerical results, the concrete strength has significant effects on the behavior of the RC load-bearing system.