| Concrete filled steel tube(CFST)is widely used in building and bridge construction because of its advantages such as high strength,light weight,good antiknock characteristics,excellent plasticity and ductility,convenient construction and so on.T type node of main arch of CFST arch bridge is the key position,but the concrete cavity caused by the discontinuity of the arch perfusion,perfusion after the completion of the concrete shrinkage and bridge vehicle fatigue load seriously affects the safety and stability of the bridge structure.Therefore,experimental method is used in this thesis to analysis different degree of influence on the flexural performance by cavity force of concrete-filled steel tube,in order to make sure the safety of concrete filled steel tubular structure.Firstly,the bending test of cavity CFST through the 10 flexural test results,analysis the influence of cavity on component load deflection curves,load strain curves,load slip curve,the core concrete mechanical properties.and the change rules of concrete filled steel tube bending deformation capacity,bearing capacity,stress distribution by different degree cavity of main tube.Then by using ABAQUS finite element software to calculate the bearing capacity and corresponding load deflection curve of empty steel tube,steel tube concrete,cavity concrete filled steel tube,discusses the effect of the core concrete slipping on results,and respectively establishes non-slip and slip model,to find that there is no slip or negligible slip inthe specimen produces.comparing to the test results.,The calculation results tallies with the experimental results.Use the method of equivalent section to analysis the two important parameters of cavity CFST,bending strength and elastic modulus of the composite body,and compare with the existed results to find thatthe error of calculation results of bearing capacity is less than 10%.this thesis gives cavity CFST 5mm,15mm,25mmrelative to the stiffness of steel slab the concrete flexural coefficient;summarizes the mechanical properties of bending process of the cavity concrete filled steel tube,and puts forward the practical calculation method of bending void CFST.In this thesis,the concrete filled steel tubular flexural members in different degrees of cavity are studied systematically,and the relevant design ideas and suggestions are put out,which has important significance for the theoretical study of cavity CFST bending,and also lays a foundation for the engineering design and application. |
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