Research On Seismic Performance Of Reinforced Angle Bolted Beam-to-column Joint

The semi-rigid joints connected by angles have attracted widespread attentions due to their good deformability and energy dissipation capacity,and have become the focus of research by scholars at home and abroad.Because the angle joint has small initial stiffness and bearing capacity,the shortcomings of this joint limit its application.Therefore,based on the traditional angle joint,this paper designs a reinforced angle joint that welds restraining ribs on the angle stiffeners.At the same time,it takes advantage of the high yield strength of high strength steel to design a reinforced angle joint form that replaces ordinary steel stiffeners with high strength steel stiffeners.Compared with ordinary stiffener angle bolted beam-to-column joints,the two types of reinforced angle bolted beam-to-column joints,can greatly improve the initial rotation stiffness and bearing capacity.In this paper,through physical experiment research and finite element simulation analysis,the seismic performance of reinforced angle bolted beam-to-column joints is systematically studied.First,by carrying out 12 cyclic loading tests about reinforced angle bolted joints,the bending moment-rotation hysteresis curve of each joint tested was obtained,the failure mode,bearing capacity,hysteresis performance,ductility coefficient,and the energy dissipation capacity of each joint were analyzed and evaluated.At the same time,the failure mode and hysteresis curve of the joints under two different column forms of box-column and I-column are compared and analyzed,and the seismic performance’s recoverability of the joints is explored by using I-beams and I-columns.Secondly,the ABAQUS finite element software is used to establish a three-dimensional nonlinear finite element model for the above test,and compare with the test results for verification.Finally,the parameter analysis of the reinforced angle bolted joints is carried out,the influence of the thickness of the angles,the thickness of stiffeners,and the thickness of restraining ribs on the mechanical properties of the joints are studied,and it is determined the initial rotational stiffness range of the reinforced angle joints are used in common beams and columns.Through experimental research and finite element simulation analysis,the main research results are as follows:1.The reinforced angle bolted beam-to-column joints have higher initial rotational stiffness and better bearing capacity than the ordinary angle bolted beam-to-column joints,and the ductility still meets the requirements of the building’s seismic design code.2.The bending moment-rotation hysteretic curve of the reinforced angle bolted beam-to-column joint under cyclic loading is relatively full,indicating that this joint has a good energy dissipation capacity under cyclic loading.3.The joints with stiffeners on both sides of the angle have better bearing capacity,and the joints with the stiffeners in the middle of the angle have higher initial rotational stiffness.4.During the test,the strain of the I-beam and I-column stays in the elastic stage and the bolt hole has not deformed,indicating that the reinforced angle joint designed in this paper is recoverable within a certain range of strength and stiffness.Replacing the vulnerable part of the joint can restore the bearing capacity and seismic performance of the joint.5.The joint of the stiffener on both sides and the high-strength steel stiffener joint with the stiffener in the middle are more suitable for the I-beam-to-I-column,the welding restraint rib joint with the stiffener in the middle is more suitable for the I-beam-to-box-column;different column forms have little effect on the failure mode and hysteresis performance of the joint,which shows that the reinforced angle joint designed in this paper has good adaptability to different columns.6.The thickness of the angle has a significant effect on the initial rotational stiffness and yield bending moment of the joint.The thickness of the stiffener has a greater impact on the initial rotational stiffness and yield bending moment of the joint.The thickness of the restraining rib has little effect on the initial rotational stiffness and yield bending moment of the joint.7.Through parameter analysis,the approximate range of the initial rotational stiffness of the reinforced angle joints with the thickness of 8mm angle and 6mm stiffeners and common beam and column joints is obtained.Which provides scientific basis and reference for this joint design.