Analysis Of Mechanical Behavior Of Beam-Column-Slab Joints Of Concrete Frame

Under earthquake,the stress in the joint area of concrete frame structure is very complex,which is usually the weak part of the seismic system.The premise of normal use of the structure is the reliable work of the joint area.Relevant scholars have done a lot of research and achieved a lot of results on seismic design of reinforced concrete frame joints.A large number of earthquake disasters show that the damage of concrete frame structure is mainly caused by the plastic hinges of frame columns.The reason that does not conform to the design concept of "strong column and weak beam" is that the code does not consider the strengthening effect of cast-in-place slabs on the bending properties of beams.Because of the role of cast-in-place floor in the actual frame,the bending capacity of beams is larger than that of columns,and the phenomenon of "strong beam and weak column" appears.Therefore,attention should be paid to the influence of failure mechanism of reinforced concrete frame structures with cast-in-place slabs.In view of the influence of cast-in-situ slab on the performance of beam-column joints of frame structures,the assumption of rigid joints under "strong column and weak beam" is no longer applicable when analyzing the performance of frame structures under strong earthquakes,so the influence of cast-in-situ slab is suggested to be considered.The seismic design method of joint area has become an important direction for further research.With the development of computer technology,the application of finite element software in engineering modeling and analysis is more and more mature and extensive,and numerical simulation has become an important research method besides experimental research.The following is the main work of this paper:1.Through the low-cycle reciprocating loading test of reinforced concrete beam-column-slab joints,the mechanical properties of reinforced concrete beam-column-slab joints are analyzed.The load-deformation hysteresis curve,shear stress-shear deformation curve in the core area of joints,strain analysis of cast-in-place slab reinforcement,energy dissipation of joints and strain analysis of stirrups in the core area are obtained.2.The finite element software is used to simulate the reinforced concrete beam-column-slab joints,and the test results are compared with the simulation results to verify the accuracy of the program simulation.3.Cast-in-place slab can improve the stiffness of beam.If it is not considered in design,it is disadvantageous to realize the design principle of "strong joints and weak members".Taking the middle joints and edge joints as models,considering the influence of cast-in-place slab,the joints with and without slabs are modeled and analyzed separately.4.Comparing each test sample and analysis model,the seismic performance analysis results of reinforced concrete beam-column-slab joints considering the effect of cast-in-place slabs under low cyclic loading are studied,and the corresponding conclusions are drawn: the existence of slabs increases the bending stiffness line of beams;cast-in-place slabs increase the input of joint shear force,and weaken the energy consumption of joints.