Research On Modeling Method Of Steel Fiber Reinforced Concrete Beam-column Joint Based On OpenSEES

Under the influence of earthquake,the inelastic deformation of the core area of the joint is the key factor that affects the force performance of the concrete pillar node of reinforced steel fiber,including the shear deformation of the core area of the joint and the sliding of the bonding of the rebar.With the rapid development of computer technology,finite element analysis has become one of the important means to study the seismic performance of steel fiber concrete beam column joint,and it is the key to ensure the accuracy of numerical simulation to correctly consider these two inelastic deformations in the finite element model.The beam column joint unit model in OpenSEES software takes into account the two deformation mechanisms of the cut deformation and the steel bond slip deformation in the core area of the joint,but the parameters of the shear block component and the steel bond slip transfer component in the model are determined according to the calculation method proposed by the test results of the common reinforced concrete beam column joint,and the influence factors of steel fiber are not taken into account.Therefore,this paper considers the incorporation of steel fiber,corrects the method of determining the parameter determination of the shear block component and the steel bond slip component of OpenSEES middle beam column joint model,puts forward the model applicable to the reinforced steel fiber concrete beam column node,verifies the accuracy and validity of the model,and on this basis,carries out the parameter expansion analysis of the reinforced steel fiber concrete beam column node,discusses the influence of each design parameter on the core area of reinforced steel fiber concrete column node.The calculation method of anti-shear carrying capacity of reinforced steel fiber concrete beam column node is derived.The specific research in this paper is as follows:（1）This paper simulates the completed reinforced steel fiber concrete beam column joint test in China by using the beam column joint unit model which has been incorporated into OpenSEES software,and analyzes the accuracy and applicability of the beam column joint model for the numerical simulation of reinforced steel fiber concrete beam column joint,and the results show that there is obvious error in the beam column joint model used to simulate reinforced steel fiber concrete beam column joint.（2）On the basis of the beam column joint unit model,considering the influence of steel fiber,based on the force characteristics of reinforced steel fiber concrete beam column joint,the fixed parameter method of shear stress-shear strain relationship curve and rebar slip displacement component in the beam column joint model is corrected,and a joint unit model suitable for seismic performance analysis of reinforced steel fiber concrete beam column joint is proposed.On this basis,the numerical simulation analysis of the reinforced steel fiber concrete beam column joint proposed static test completed by domestic scholars is carried out,and the applicability and validity of the model are verified according to the overall reaction and local inelastic deformation reaction.（3）Based on the joint unit model proposed in this paper,a finite element analysis model of reinforced steel fiber concrete beam column joint is established,parameter expansion analysis is carried out on reinforced steel fiber concrete beam column joint,the effect of steel fiber volume rate,shaft pressure ratio and core area clamp rate on the seismic performance of beam column joint is studied,and the effect of each change on the limit load and stiffness degradation of reinforced steel fiber concrete beam joint is analyzed.（4）By analyzing the influence of steel fiber volume rate,shaft pressure ratio and core area hoop amount on the core area by shear carrying capacity,the shear carrying capacity calculation formula is derived for the core area of reinforced steel fiber concrete beam column joint.Using the formula to calculate the sheared carrying capacity of the core area of the node in the test of reinforced steel fiber concrete pillar node in China,the calculated value is compared with the test value to verify the accuracy of the formula.