Investigation of the effects of ground motion and number of stories on the seismic behavior of multi-story reinforced concrete buildings

In this thesis, the effect of ground motion level and number of stories on the seismic performance of multi-story reinforced concrete structures is investigated. Analytical studies were carried out using the SAP2000 finite element software. Two cities in Turkey with different seismic hazard levels, Istanbul and Konya were selected as case study regions. For each city, four different buildings with 7, 8, 9, and 10 stories were modeled. The structural design and analysis were conducted in accordance with the Turkish Seismic Code (TBDY 2018), considering DD-2 and DD-3 earthquake ground motion levels. The seismic behavior of the buildings was evaluated based on irregularity criteria defined in the code, including torsional irregularity, soft-story irregularity, inter-story drift irregularity, and second-order (P-Δ) effects. The results indicated that torsional irregularities became more pronounced as the structural period decreased and frequency increased. It was observed that the higher lateral stiffness in the X-direction resulted in better seismic resistance in that direction, leading to lower lateral displacements compared to other axes. In all models, the second story exhibited a notable tendency toward soft-story irregularity. However, inter-story drift irregularities remained within acceptable limits for most of the floors. The findings demonstrate the significant influence of both the number of stories and ground motion level on structural irregularities and overall seismic performance. The study emphasizes the critical importance of accounting for these parameters in the design phase to ensure earthquake-resistant structural systems.