Bearing Capacity Analysis Of Composite Shear Wall With CFST Boundary Columns Incorporating FRP-confined Concrete Core

In recent years,reinforced concrete shear wall plays an important role in the building structure as the main lateral force resisting elements in high-rise and super high-rise buildings.RC shear walls at the lower parts of the buldings need to be thickened to meet the requirements for the axial compression ratio specified in the existing codes which greatly reduced the effective utility area of the building.More and more research has been conducted on composite shear walls to improve the overall performance of shear wall.Based on the advantages of fiber reinforced polymer(FRP)tube-confined concrete and concrete-filled steel tube(CFST),a new composite shear wall with FRP-confined concrete cores embedded in the CFST boundary columns is proposed in this paper.Experimental study has been conducted on the composite shear wall.The failure mode,bearing capacity and plane-section assumption are analyzed.Based on the plane hypothesis and the simplified constitutive relation of concrete-filled steel tube as polynomial function,the bearing capacity of the new composite shear wall is theoretically analyzed and derived by using the concrete equivalent stress method.Simulation of composite shear wall has been conducted by the finite analysis software ABAQUS to verify the proposed bearing capacity formula.The main contents in this paper include the following aspects:(1)The descending segment function of the constitutive relation of concrete-filled steel tube is simplified as a polynomial function which is convenient to calculate;(2)Referring to the method of calculating the ultimate bearing capacity of ordinaryreinforced concrete compression members,the stress calculation formula of the compressed concrete in the concrete confined steel tube and concrete confined FRP tube are analyzed and derived on the basis of the plane hypothesis.This stress calculation formula of concrete filled steel tubular column and FRP tube concrete column can be furtherly used to calculate the ultimate bearing capacity of the CFST columns and FRP-confined concrete columns.(3)Based on the research results of(1)(2)and the analysis method of the ultimate bearing capacity of the ordinary shear wall,the ultimate bearing capacity formula of composite shear walls with CFST boundary columns incorporating FRP-confined concrete is derived.The bearing capacity formula turn out to be feasible and correct by comparing the calculation results with the test results;The shear bearing capacity of the composite shear wall is preliminarily derived in this paper.(4)The finite element analysis model of composite shear wall with CFST columns incorporating FRP-confined concrete is established using ABAQUS to verify the bearing capacity formula;30 finite element models with different parameters are analyzed;The numerical simulation results are compared with the calculation results of the bearing capacity formula of composite shear walls,which further verifies the correctness of the bearing capacity formula.