Hazhir KAHRIZI - Graduate student in Struct. Eng., Dep. of Civil and Environmental. Eng, TarbiatModares University, Tehran, Iran
Ali Akbar AGHAKOUCHAK - Prof. of Struct. Eng., Dep. of Civil and Environmental.Eng, TarbiatModares University, Tehran,Iran

Concentrically braced frames (CBFs) are widely used as lateral-load resisting system in steel structures.They are economical, and their strength and stiffness may satisfy seismic demand of structures in seismic regions. During severe, infrequent earthquakes, brace yielding and buckling occurs, and this behavior provides the ductility and the energy dissipation capacities for structures. In recent years, a number of studies have examined different factors, which influence the performance of SCBFs; in particular, the gusset plate and the brace member details. This study is carried out to investigate the effect of column orientation and the resulting flexibility of the connection region on the overall behavior and performance of the system. Nonlinear analyses using a detailed inelastic finite element model (FEM) and the concept of plastic equivalent strainare carried out to study the behavior of frames subjected to cyclic loading.The results showed that the flexibility of the connection region caused by column orientation affects the overall response of the system including lateral load and ductility capacity.

Steel Concentrically Braced Frames, Seismic Behavior, Column Orientation.