Study On The Seismic Behavior Of Frame Joints With SRC Columns And Steel Beams And Steel-concrete Composite Beams

In the California Northridge earthquake in the United States and the Kobe earthquak in Japan in 1990 s,a large number of steel structures were in large-scale destruction,which was caused by many reasons,and the damage caused by column-beam joints was prominent Therefore the design and safety of column-beam joints are extremely important.It is necessary to study the seismic performance and design calculation theory of steel-concrete composite joints in depth.In this article,the mechanical and seismic behavior of joints of SRC columns and steel beams and joints of SRC columns and steel-concrete composite beams are studied.The main work of this article is as follows:(1)The pseudo static experiments on the behaviors of 3 1/2 carrying capacity scale steel-concrete joints(including 1 joint with SRC columns and steel beams and 2joints with SRC columns and steel-concrete composite beams)have been conducted.The test parameters varied included the width of slab and with slab or not.In order to study the mechanical properties of the SRC composite joints,the hysteretic behavior,failure development,stiffness degradation law,bearing capacity degradation law,shear resistance,displacement ductility and strain in some places were evaluated at length.By adopting the antisymmetric loading forms at the ends of beams the earthquake action was simulated.The experimental results made it clear that the shear failure characteristics were obvious,but the composite joints still have higher bearing capacity,good ductility and excellent energy dissipation performance.Compared with SRC1,SRC2 and SRC3 show higher bearing capacity,better ductility and better seismic performance.(2)Taking the joints as models with actual dimensions of the joints in the test,the entity modeling and the meshing of joints have been accomplished by the use of the numerical simulation software ABAQUS,which can make reasonable choice of boundary conditions and the definition of load application according to objectivecondition of test site,so the process of single and cyclic loading of the finite element analysis has been conducted.The combination effect of cast-in-place floor slab on the mechanical properties has been analyzed.The results of finite method calculation are in good agreement with the analysis of tests.Through numerical simulation,more details can be obtained,which are extremely difficult to measure in experiments,such as: the stress distribution development of steel flange and web of the column and the stiffener in the core region,stress distribution characteristics and damage development of the reinforced concrete slab.The influence of the slab thickness,the concrete strength and the reinforcement ratio of the longitudinal reinforcement on the mechanical properties of the joints are studied.Based on the analysis results,some suggestions are put forward for the seismic design of the combined nodes.