Finite Element Analysis on K-Type External Braced Steel Frame System

The concept of moment resisting frames with K-type external braces is proposed to increase the lateral stiffness, which has short external span and large lateral stiffness. In order to investigate the lateral stiffness, overstrength coefficient and the reduction factor of K-type external brace under horizontal load, ABAQUS was applied to study the different slenderness ratios (from50 to 150) of K-type external steel braced frames. The results showed that the lateral load and displacement curve can be divided into elastic stage, the buckling of the compressive brace-yield of the tensile brace stage and plastic stage. The overstrength of K-bracing is related to the potential bearing capacity of the frame when the compressive brace buckled, and the potential growth of the tensile brace. The overstrength coefficient increases with increasing of the brace slenderness ratio. The range of recommended values of slenderness ratios of K-type external steel braces and design values of unbalanced force of column sections are proposed.