Study of cyclic behavior of square hollow section steel braces with infill glued-laminated timber

This study investigates the cyclic performance of hollow square steel braces that incorporate infilled materials. The proposed infill brace design features gusset plates at both-ends, a prismatic square hollow section, and a solid infilled material to reduce the stress concentration in the mid-span region of the brace member. Numerical simulations based on the parameters of equivalent plastic strain and von Mises stress were conducted to evaluate the behavior of different infill materials, including wood, glued-laminated timber, and H-beam. A series of full-scale brace specimens using glulam infill materials were subjected to experimental cyclic tests to assess failure mode, strength, stiffness, ductility, and energy dissipation. This proposed strategy effectively spreads stress concentration in the mid-span, improves ductility and energy-dissipation capacity, and maintains similar strength and stiffness compared to conventional braces, which are beneficial for retrofitting existing structures at risk of insufficient resistance to low-cycle fatigue. The design parameters proposed should be followed in two steps to achieve the favorable mechanisms of this method in practical applications.