| Under earthquake load,concrete frame structure,especially beam-column joint,is vulnerable to various kinds of loads.As a kind of cement based material with super high performance,the mechanical property of RPC(Reactive Powder Concrete)is different from that of the normal concrete.In order to study the behavior of RPC beam-column joints under earthquake load,based on the pseudo-static test of RPC beam-column joints done by our research group,the paper makes a numerical simulation of RPC beam-column joints by using OpenSEES software.On this basis,the static nonlinear analysis of a two-span and three-story RPC and RC frame is carried out to study the seismic behavior of the RPC frame.The main research work and related results are as follows:Simulate the RPC beam-column by OpenSEES software,the displacement-load hysteresis curves and skeleton curves obtained by numerical analysis and test are compared.We can draw the following conclusions: in the elastic phase of the curve,the hysteretic curve and skeleton curve of the RPC joints obtained from OpenSEES are similar to the experimental results,and are approximately straight lines.In the ascending and descending stages of the curves,the trends of the two curves are generally similar,and the simulation results are good.It can be found that using OpenSEES to simulate RPC beam-column joints is feasible and reliable.The parameters of RPC beam-column joints are analyzed including axial compression ratio,reinforcement ratio of longitudinal column,reinforcement ratio in joint core area,reinforcement ratio of longitudinal reinforcement of beam.The influence of single factor on the seismic performance of RPC beam-column joints are studied by means of control variable method.When the axial compression ratio is within 0.3-0.5,the peak bearing capacity of the RPC joints will increase with the increase of the axial compression ratio.When the axial compression ratio exceeds 0.5,the peak bearing capacity and ductility of the joints will decrease significantly with the increase of the axial compression ratio.The ductility decreases with the increase of longitudinal axial pressure.The increase of reinforcement ratio of longitudinal reinforcement in beams and columns can effectively improve the peak bearing capacity of RPC joints,and the increase of stirrups in the core area of the joints can significantly enhance the ductility of RPC joints.According to the modified compression field theory(MCFT),the shear capacity of the core area of RPC beam-column joint is analyzed.It is concluded that the shear capacity of RPC joint core area is mainly composed of longitudinal reinforcement bearing capacity,RPC bearing capacity and steel fiber bearing capacity.Based on the theoretical analysis,the formula forcalculating the shear capacity of the core area of RPC beam-column joint is derived and compared with the shear capacity of the core area of the joint obtained in the experiment.The results are well fitted.The static nonlinear analysis of a two-span and three-story RPC frame is carried out.The seismic behavior of RPC frame and RC frame under horizontal inverted triangular load is studied,the lateral displacement and interlayer displacement angle in two cases are obtained.And according to the seismic code,compare them with the limit value of the interlayer displacement angle frame structure.The results show that the seismic behavior of RPC frame is better than that of normal concrete frame,and the interlayer displacement angle is obviously reduced. |
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