Investigation On Seismic Behavior Of Steel Reinforced Concrete Beam-column Joints

Compared with the reinforced concrete structures,steel reinforced concrete structures(SRC)have characteristics of high bearing capacity and good ductility,In the earthquake it has a tremendous advantage.so it has been applied in engineering widely.However,under action of strong earthquake,plastic hinge at beam end may induce brittle fracture of welded joint between beam and column and entry joint core,which may reduce the seismic behavior of the SRC structure significantly.In this dissertation,a new technique of heat treatment reduced beam section(HBS)is proposed for steel flanges at beam end.A heat-treating process with ultra-high temperature heating and subsequent controlled slow cooling could have a weakening effect on local steel strength,so as to transfer the plastic hinge from the beam end to the heat treated reduced section(HBS),and manual controlling plastic hinge area.This may improve the seismic behavior of the SRC beam-column joint and has important significance in theory and value in engineering.This paper selects finite element software ABAQUS,by selecting the appropriate element type,material model parameters the finite element model of the SRC connection is established.Then there conducts a research concerning seismic performance of the new joints on the heated beam and the failure mechanism.Meanwhile,comparison analysis with the mechanic property of dog-bone style beam edge node is also conducted.The main research contents and results are as follows:1.Taking a project which has been built according to the China's design specifications of relevant as the background,this paper discussed the modeling methods to establish the SRC beam-column joint refinement model,and through mechanical properties of the model and hysteretic behavior of structures comparative analysis,to verify the finite element model correct.The results can be applied in other related mechanic property analysis.2.Based on the finite element model of the SRC connection established in this paper,steel reinforced concrete beam flange is simulated by local heat treatment.Through the test of HBS beam-column joint specimens under cyclic loading,the bearing scapacity,ductility,energy dissipation and hysteretic characteristics of the beam-column joints of SRC member with heat treated beam section are studied.Also,the failure mechanism and damage performance of the beam-column joint and the function of the heat treated beam sections on the bearing capacity of the beam-column joint are investigated.Results show that the novel heat-treating process also has a significant weakening effect on Chinese Q345 B steel.Theenergy dissipation capacity and seismic behavior of steel reinforced concrete beam column joints with HBS are better than those with RBS.3.Based on the finite element model of steel reinforced concrete joints.The simulation analysis of SRC beam-column joint with dog-bone type reduced beam section(RBS).Analysis results show that: the beam-column joint of SRC composite with dog-bone type reduced beam sections has good ductility,strong deformation ability and high energy dissipation,therefore has advanced seismic behavior.But the disadvantage is that the depth and position of the flange,and the welding quality of the beam column joint have great influence on the dog bone type RBS.