RESEARCH ON THE INFLUENCE OF GUSSET PLATE CONNECTIONS ON THE OUT-OF-PLANE STABILITY OF THE H-SHAPED STEEL BRACE

Experiments on 12 specimens of H-shaped steel bracing members with gusset plate connections (brace system) are conducted to study the effect of gusset plate on the out-of-plane rotational restraint and stability capacity of the brace. The experiments are under cyclic loading with constant-amplitude axial displacement, and the effect of clearance distance on the stability capacity of the brace is obtained. For the cyclic constant-amplitude loading condition, the degradation criterion of stability capacity of the brace system is obtained and the calculation formula of the post-buckling capacity is suggested. The finite element method is used to simulate the behaviors of specimens, and the simulated results are in good agreement with the experimental results. Moreover, a large-scale parameter analysis of the full-sized brace system is carried out. The results indicate that the brace slenderness ratio, the thickness of the gusset plate, the clearance distance and the brace angle have significant impacts on the out-of-plane rotational stiffness and stability capacity of the brace system. Based on the influence of these critical parameters on the rotational restraint of gusset plate and considering the size effect, the formulas for calculating the rotational stiffness of the gusset plate connection and the effective length factor of the brace are proposed, which can be used to easily obtain the stability capacity of the brace system.