| Reinforced concrete slab column structure has the advantages of thin structure thickness,which can effectively save the space between floors and improve the space utilization rate,so it is widely used in underground garage,residence,school and other buildings.However,due to the large bending moment and shear force in the splatecolumn joint area,the splate-column joint is prone to brittle punching failure,which causes heavy casualties and property losses.So far,the failure mechanism,antipunching mechanism and calculation method of bearing capacity of slab-column joints have been one of the important topics in the research field of slab-column joints.In order to improve the anti-punching performance of slab-column joints,this paper analyzes the anti-punching performance of steel and concrete composite slabcolumn joints by means of experimental research,finite element analysis and theoretical derivation.Twelve 1/5 scale scale test models were designed and made as the research parameters,such as the type of nodal steel,the ratio of longitudinal reinforcement,the strength of concrete,the thickness of slab and the ratio of section steel.Test each component of the vertical load through monotonic loading test-slab center deflection curve,the strain of steel,etc.,analyses the load displacement curve,the ultimate bearing capacity,ductility and energy dissipation mechanics performance,in addition,on the basis of the test to establish the numerical analysis of the steel and concrete slab-column node model,dynamic mechanism research and analysis.The results show that the anti-punching performance and ductility of the joints can be significantly improved by the arrangement of section steel in the splate-column joints,and the anti-punching performance of the joints will be improved to different degrees with the increase of the number of section steel,the steel ratio of longitudinal bar,the strength of concrete,the thickness of slab and the steel ratio of section steel.The bad characteristics of composite slab-column joints are as follows: when the joints are under stress,the concrete at the bottom of the slab is firstly pulled apart and cracked,then the longitudinal ribs of the slab and the lower flange of the section steel are subjected to tensile yield,and finally the concrete at the periphery of the column is crushed,which has obvious ductility failure characteristics.In addition,the research on the punching failure mechanism of composite slate-column joints of steel reinforced concrete shows that the punching failure surface of composite slate-column joints is composed of two parts: the punching failure surface formed by the column against the plate and the punching failure surface formed by the steel beam against the plate... |
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