The effect of vertical earthquake acceleration on building behavior in reinforced concrete buildings with different overhang ratios

The concept of vertical spectrum started to be implemented in Turkey with the Turkish Building Earthquake Code 2018 (TBDY 2018). Before this regulation, earthquake analysis was carried out under horizontal loads with only the horizontal spectrum in buildings and it was predicted to stay on the safe side with the axial load limitation made on the columns. In TBDY 2018, vertical earthquake analysis is performed depending on the structural defects in the structures. In this study, equivalent earthquake load method, mode combination method and linear analysis in the time history and vertical earthquake analyzes were performed on the building samples with different ratios of cantilever overhangs in five different cities we determined. During these analyses, the vertical earthquake acceleration assumption made in the earthquake code and the analysis results obtained from the vertical earthquake spectrum were examined. For this purpose, firstly, the horizontal earthquake forces under the equivalent earthquake force, the axial load levels on the columns and the section effects and displacements on the cantilever supports were obtained. These results were compared according to TBDY 2018, EC8-4 and ASCE 7-16 earthquake codes, which are dynamic analysis, vertical spectrum analysis with mode fusion method, and data obtained from linear analysis in time history. The results obtained show that the assumptions made in the equivalent earthquake load method are on the safe side, and it has been seen that the results vary due to some rules and differences arising from the regulations.