Türkiye bina deprem yönetmeliği 2018'e göre tasarlanmış ters V merkezi çaprazlı çelik çerçevelerin sismik performans değerlendirmesi

Concentrically braced frames (CBFs) are commonly preferred in high seismicity areas to provide resistance against seismic loads. After significant damages were observed in moment frames during the Northridge (1994) and Kobe (1995) earthquakes, CBFs have become more popular owing to high stiffness and strength. Thus, research has been focused on behaviour of CBFs under severe earthquakes. One of the configurations of CBFs is chevron (or inverted-V) braced frames (IVBFs) is also used in structures because of their architectural advantages. In chevron arrangement, while one of the story braces resist compression, the other one resist tension. Chevron CBFs require special consideration in design. Because, under a lateral loading when the compression brace buckles, the downward force emerges at the midspan of the beam. This unbalanced force can lead to formation of a plastic hinge at the midspan of the beam and collapse of the structure. To avoid such an undesirable mechanism, the Turkish Building Earthquake Code 2018 (TBEC) that superseded the Turkish Earthquake Code 2007 introduced two yield mechanisms. TBEC requires the beams, columns, and connections of IVBFs to be designed to resist the axial and flexural demands obtained from two yield mechanisms. In this study, firstly, a two-story IVBF was designed per TBEC considering new provisions and changes such as yield mechanism, earthquake ground motion intensity levels, and performance levels. Nonlinear response-history analyses were conducted to evaluate seismic performance of IVBF under ground motions. Secondly, incremental dynamic analysis (IDA) of a two-story IVBF designed to TBEC was performed. Capacity points were determined for each IDA curve and the collapse fragility curve of the frame was obtained. Collapse margin ratio defined in FEMA P-695 was calculated. Finally, the acceptability of calculated collapse margin ratio was evaluated.