Study On Seismic Performance Of Q690 High Strength Steel Plate Reinforced Joints

Traditional welded joints have greater rigidity,Insufficient rotation capacity of the joints,It is difficult to carry out plastic deformation of materials under strong earthquakes,Very vulnerable to brittle failure.The steel structure joints in the seismic fortification zone should have good rotation ability while having sufficient bearing capacity.The plate-type reinforced joint can not only improve the bending bearing capacity of the beam end,make the plastic hinge move to a position other than the reinforcement plate,but also effectively ensure that the weld at the beam end does not undergo brittle failure and improve the ductility.Simultaneously,Due to high tensile strength of high-strength steel,The component adopts high-strength steel plate,on the one hand,it can reduce the size of the component,on the other hand,it can also obtain a bearing capacity similar to or even higher than that of ordinary steel thick plates.therefore,In this paper,the highstrength steel plate-type reinforced joint is taken as the research object,and the seismic performance of the high-strength steel plate-type reinforced joint is systematically studied.The seismic performance is evaluated and at the same time,the reasonable recommended value of each component is given.The main tasks are as follows:Low cycle repeated loading test on 6 Q690 high-strength steel plate reinforced joints,Reveal the destruction mechanism and energy consumption mechanism of joints,Discussed the influence of factors such as different strengthening forms,steel strength grades,and joint field reinforcement measures on joint performance,Key performance indicators such as bearing capacity,stiffness,ductility,and energy consumption of the joint were quantitatively analyzed,and the superiority of the seismic performance of the high strength steel plate reinforced joint was evaluated.the result shows:Because the cover plate and the beam flange are directly welded to the column surface,the connection rigidity is large,the rotation binding force to the joint is strong,the joint deformation ability is weaker than the "plate transition type"joint,The use of ordinary steel for steel beams will reduce the bearing capacity of the joints,but can achieve higher“plate transition type”joint,The use of ordinary steel for steel beams will reduce the bearing capacity of the joints,but can achieve higher ductility and energy consumption.After the joint zone repair welding steel plate is strengthened,It can improve the bearing capacity of nodes but limits the turning ability of the joints.Establishment of finite element model of high-strength steel plate reinforced joints,Perform cyclic loading numerical simulation,Comprehensive analysis of key performance indicators such as joint carrying capacity and ductility,The results are compared with the test results to verify the accuracy of the finite element model.The result shows:the maximum difference of their peak loads was 12.4%and the maximum difference of their corner limit was 5%.It shows that the finite element analysis is feasible and lay the foundation for subsequent variable parameter analysis.In order to make the values of each component more reasonable,the above finite element model was used to carry out the finite element parameter expansion analysis.The effects and degrees of the influence of the length and thickness of the flange transition plate and the cover plate reinforcement plate,the thickness of the reinforcement plate,and the strength grade of the steel on the seismic performance of the joint are mainly discussed.The optimization of parameters was achieved,the recommended value range was given.For flange plate transition joints,it is suggested that the length of the flange plate should be(0.6～0.85)hb and the thickness should be(1.2～1.4)tb.For cover plate reinforced joints,it is suggested that the length of the cover plate should be(0.6～0.85)hb and the thickness should be(0.7～1.1)tb.Take the US《Code for Seismic Design of Steel Structures》and China《Code for Seismic Design of Buildings》,《Code for Design of Steel Structures》,《Technical Regulations for Steel Structures for High-Rise Civil Buildings》as examples,The relevant provisions of the two countries’ regulations on the design of plate reinforced joints are summarized,and the differences between the two are compared and analyzed.Finally,the detailed design steps and verification process are given by taking the test pieces used as examples as an example.The applicability of the existing code to the design method and calculation formula of Q690 high-strength steel plate reinforced joints was verified.