Influence of Column Section on the Seismic Behavior of Special Concentrically Braced Frames

Steel braced frames are commonly used lateral-load resisting systems indesign codes. Special concentrically braced frames (SCBFs) are increasinglyused in seismic regions in recent years due to their satisfactory behavior anduncertainty as to the performance of special moment resisting frames after the١٩٩٤ Northridge Earthquake. In SCBFs, the braces are connected to thebeams and columns by gusset plate connections, and energy dissipation isprovided by the tensile yielding and post buckling deformation of the brace.In recent years, a number of studies have examined different factors, whichinfluence the performance of SCBFs. Most past experiments focused on thebehavior of the gusset plate and the brace member.This study is carried out to investigate the effect of column section and theflexibility of the connection region caused by that on the overall behavior andperformance of the system. Joint flexibility exists when the column iscomposed of double column sections or when the brace is connected to thebox shape columns. The FE numerical model and the concept of plasticequivalent strain were used to predict the lateral load capacity, frame ductilitycapacity, and possible failure modes. A parametric study was performed toexamine the influence of column section properties on the performance ofspecial concentrically braced frames. The results showed that when themoment of inertia of the column is constants, the effect of column section andits local flexibility is more noticeable on the ductility capacity in comparisonto the load capacity of the frame.

Keywords:

Steel concentrically braced frames , Seismic behavior , column section