Investigation of seismic vulnerability of soft storey reinforced concrete buildings

The devastating earthquakes experienced in Turkey in recent years reveal the importance of earthquake-resistant building design. Therefore, it is an important issue that an existing building can withstand future earthquakes at the desired performance level. Considering Turkey's existing reinforced concrete building stock, it has been determined that especially buildings with soft story irregularities are severely damaged in earthquakes. Therefore, it is of great importance to take into account irregularities in reinforced concrete buildings. This thesis study aims to evaluate the possibility of damage to reinforced concrete buildings with soft storey irregularities in possible earthquakes using fragility curves. In this context, using the SeismoStruct structural analysis program, a typical 4-storey reinforced concrete building with an existing floor plan of 4.5 m and normal floors of 3 m was modelled as regular and soft storey. Nonlinear incremental dynamic and static pushover analyses of the modelled buildings were performed. 11 earthquake records were used for incremental dynamic analyses. To model the nonlinear behaviour, plastic hinges gathered at the ends of the structural elements were assumed. As a result of incremental dynamic analyses, the maximum responses, interstorey drifts and fragility curves were obtained for regular and soft storey buildings. As a result of static pushover analyses, capacity curves of regular and soft-storey buildings were created. In line with the results obtained, it has been determined that the interstorey drifts of the soft storey building increase excessively compared to the regular building, their base shear force carrying capacity decreases and the possibility of damage increases.