Seismic performance evaluation of steel braced frames under near fault effect

In the last century, recorded ground motion data from earthquakes around the world has shown that the characteristics of near-fault ground motion differ from those of far-fault records. In particular, the 1989 Loma Prieta, 1994 Northridge, 1995 Kobe, and 1999 Kocaeli earthquakes caused severe and extensive damage to structures located in near-fault regions. Compared to far-fault ground motions, near-fault ground motions impose greater displacement demands on structures. In the earthquakes that occurred in Pazarcık/Elbistan, Kahramanmaraş, on February 6, 2023, it was determined that the level of damage to structures or the number of collapsed buildings in some cities was greater in regions near the fault compared to regions farther from the fault. Therefore, this thesis investigates the effects of near-fault ground motion records on steel school structures. For this purpose, a four-story school building was designed, assuming that earthquake loads in both directions are resisted by highly ductile centrally braced steel frames (CBFs), while all other internal frames carry only vertical loads. The design of the highly ductile CBFs was carried out in accordance with ÇYTHYE 2016 and the Turkish Building Earthquake Code (TBDY 2018). The seismic performance of the capacity-designed CBFs was evaluated using nonlinear analysis methods, specifically static pushover and time-history analysis. In dynamic analyses, 30 earthquake ground motions reflecting near-fault behavior were considered to align with the study's objectives. Upon examining the results, it was observed that the buckling of the bracing elements under compressive forces was a decisive factor in the system behavior of the CBF frame. Additionally, in the dynamic analyses, the spectral matching approach for scaling earthquake ground motion records resulted in smaller displacement demands compared to the simple scaling method.