| The reinforced concrete(RC)beam-column joints are the key parts to ensure the integrity of the structure.Under the action of load,it often has to bear a large shear force,so brittle shear failure generally occurs.The destruction of joints is often difficult to repair,and even causes the collapse of the entire structure.Therefore,it is necessary to study the shear mechanics of RC beam-column joints.RC structures are often subjected to dynamic loading such as earthquakes in use,and both steel and concrete are rate-sensitive materials,so the bearing capacity,crack development,and failure modes of the entire structure or member may be changed under the action of dynamic loading.At present,there are many tests on the RC beamcolumn joints under quasi-static loading,and the influence factors of the mechanical behavior of joints is numerous.To further parameterize the dynamic shear mechanical properties of RC beam-column joints,this paper use the plastic damage model of concrete in ABAQUS software,considering the influence of loading rate,axial compression ratio and longitudinal reinforcement ratio of beams,the numerical analysis of RC beam-column joints is carried out.The main research work is as follows:(1)The research on the rate-dependent effects of reinforcement and concrete materials is reviewed,and the results on the experimental research,theoretical model research and numerical analysis of RC beam-column joints at home and abroad are summarized.(2)The plastic damage model of concrete in the ABAQUS software is described,and the iterative calculation process in the numerical solution process is introduced.The existing beamcolumn joint test was selected for numerical analysis,and the feasibility of the numerical analysis was verified by comparing the numerical analysis results with the experimental results.(3)Considering the effects of loading rate,axial compression ratio at the column end and longitudinal reinforcement ratio at the beam end on the bearing capacity,deformation performance,damage and energy consumption of the joint assembly,the RC beam-column joints under monotonic dynamic loading is analyzed by the plastic damage model.The results show that: the loading rate has a significant impact on the shear mechanical properties of RC beam column joints.Under rapid loading,the bearing capacity and energy consumption are significantly improved,and the damage distribution is also changed;the increase of axial compression ratio may bring some adverse effects;the increase of longitudinal reinforcement ratio at the beam end slightly increases the bearing capacity of the joints,but has no obvious effect on the damage distribution.(4)Considering the influence of loading rate,axial compression ratio and longitudinal reinforcement ratio at the beam end on the shear mechanical properties of the joint assembly,the cyclic dynamic loading of the RC beam-column joint is carried out.The results are similar to the monotonic loading,but because the influence of bond slip is not considered,the hysteresis curve by numerical analysis is quite different from the test,the displacement range is significantly reduced,and the degradation rate of bearing capacity is also significantly faster. |
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