Research On The Influence Of Gusset Plate Connections On The Out-of-plane Stability Of The H-section Brace

For the concentrically bracing frame with gusset plate connections,the stable bearing capacity of the bracing connection system composed of its brace and gusset plate will play an important role in the integral responses of the frame under loading.The stable bearing capacity of the bracing member is related to the constraint conditions at both ends,however,in GB50017-2017,for bracing connection with gusset plate,the constraint condition of the bracing member is assumed as hinged joint,which stipulates that the out-of-plane effective length factor is 1.0,and the gusset plate is considered to have no restrictive effect on the out-of-plane rotating of the bracing member.This method is conservative,therefore,this paper explores the problem of bracing out-of-plane stable bearing capacity and the out-of-plane rotation stiffness of the gusset plate.In this paper,the bracing system with gusset plate connections was tested,and parameter analysis by using ABAQUS.A solution method for the out-of-plane rotation stiffness of the gusset plate was established under different parameters,and then it can determine the out-of-plane effective length factor,which can provide a reference for the design value of the stable bearing capacity of the bracing member.The main contests are listed as follows:Firstly,summary of study and application status of bracing members and gusset plates was made;based on the geometric offset and loading amplitude,12 specimens were designed.The specimens were loaded by using elastoplastic equal amplitude symmetric cyclic displacement loading mode,and the relationship curve of bracing members between displacement and load was obtained.The influence of geometric offset on the stable bearing capacity of the bracing members was analyzed in detail.The influence of each parameter on the deterioration of the bracing stable bearing capacity under cyclic loading was studied,and the formula to calculate the stable bearing capacity during each cycle before failure was proposed.The influence of each parameter on the bearing capacity after buckling was analyzed,and based on the test specimens,a revised formula for the value of bearing capacity after buckling was proposed.Secondly,a refined finite element model was established based on the test specimen for simulation by using ABAQUS,and the simulation results were in good agreement with the test results.In order to facilitate the follow-up research,the refined finite element model was reasonably simplified,and a simplified model of finite element is proposed,which has a good agreement with experimental results and refined finite element simulation results,and can be used for large-scale parameter analysis.Finally,the finite elements model was established under different parameters by changing the slenderness ratio,the thickness of gusset plate,geometric offset and the angle of bracing.The stable bearing capacity of the elastic stage was obtained through the eigenvalue buckling analysis,and bring it into the theoretical formula to gain the value of the out-of-plane rotation stiffness of the gusset plate.The influence of these parameters on the out-of-plane rotation stiffness of the gusset plate was analyzed and the recommended formula for solving the out-of-plane rotational stiffness of the gusset plate was determined,which providing a a simple and feasible method to calculate effective length factor of the bracing member.