Experimental Study On Buckling Capacity Of Ultra-High Performance Concrete Filled High-strength Steel Tubular Arches

With the development and application of high-strength materials,as well as the actual demand for light-weight long-span engineering structure,high-strength steel tube-UHPC composite structure arises at the historic moment.Compared with ordinary concrete,UHPC(Ultra-High Performance Concrete)has high strength,good ductility and light weight.The high strength steel pipe has higher compressive resistance than the ordinary one,but its plastic deformation ability is poor.The combination of the two can greatly improve the bearing capacity of the structure by complementing each other to realize the light and large span of the structure.And it can also broaden the application scope of the composite structure.In this paper,the bearing capacity of concrete-filled steel tubular arch composed of high-strength steel tube and UHPC is studied by experiment and finite element simulation,and the design formula for the bearing capacity of high-strength steel tube UHPC parabolic arch is constructed.The specific content is as follows:(1)Research on bearing capacity of high-strength steel tube-UHPC parabolic arch(UHCFST).In this paper,two groups of parabolic arch rib specimens with different UHPC strength are designed and processed(three specimens in each group).The in-plane and the out of plane bearing capacity test are carried out respectively.The detailed loading scheme is formulated.The five point vertical symmetrical step loading is adopted.The stress characteristics of the specimens in the whole loading process are read and recorded in real time.The bearing capacity and failure mode of the specimens are obtained,and the failure mechanism of UHCFST arch is revealed.(2)Numerical analysis of high strength steel tube UHPC parabolic arch.The finite element analysis model of UHCFST parabolic arch is established by ABAQUS software.As the important calculation parameters of the finite element model,the hoop coefficient is calculated by using the material properties and geometric parameters of high-strength steel pipe and UHPC measured in the test,and the bearing capacity of uhsft parabola arch is calculated.In addition,the influence of the initial defects of the arch is considered.The load-displacement curve and load-strain curve of the specimen in the loading process are obtained to be compared with the experimental results.The reliability of the experimental results and the accuracy of the finite element model are verified by comparative analysis.(3)The calculation formula of stable bearing capacity of UHCFST arch is proposed.Based on the test data and the analysis results of 1800 finite element model parameters,the influence of steel tube strength,UHPC strength,rise span ratio,slenderness ratio and steel ratio on the bearing capacity of the arch is analyzed through the control variable method.The calculation formulas of in-plane and out of plane stability bearing capacity of UHCFST arch under uniform load are proposed to guide the engineering design.