The Pure Torsional Performance Test Research Of Steel Webs (Board)- Concrete Composite Box Girder

The steel webs-concrete composite box girder structure and the corrugated steel webs-concrete composite box girder structure (hereinafter collectively referred to as the two new composite structures of steel webs (board)-concrete composite box beam) are two new types of composite structure. They have many advantages such as small weight, attractive appearance, and convenient construction. The papers mainly conduct the pure torsional performance of the test and theoretical study. The main work and conclusions in this paper include the following:(1) This paper launches the pure torsion test of the steel webs (board)-concrete composite box beam. The results showed that the two composite beams have the same torsional properties under the pure torsion effect. In the beginning of loading, the torque and torsion’s curve is linear growth, and the structure has greater stiffness. When the torque close to cracking torque, structural stiffness begins drastically reduced, and the torque and torsion’s curve is nonlinear growth. And structural stiffness continues to reduce until the structure of the overall destruction.(2) The finite element models of the steel webs (board)-concrete composite box beam had been built in this paper using the ANSYS. And the finite element calculation results with the experimental results are consistent and verify the correctness of the finite element model. Used the true finite element method, this paper also establishment of a standard finite element model of the cross-section of the real bridge, and calculates the torsional rigidity, cracking torque, and ultimate torque.(3) The existing calculation methods of the torsional rigidity had been verification, which used the method of combination of finite element analysis and test analysis. Because of being ignored the contribution of the flange plate to torsional stiffness of the structure. So the torsional stiffness calculated using the formula is than the experimental value/finite element value lower 10%.(4) Refer to the cracking torque calculation method of concrete box girder, this paper proposes the cracking torque calculation method of the steel webs (board)-concrete composite box beam under the test and finite element analysis. The cracking torque which used the methods of this paper is close to the result of test or finite element. Because of being ignored the cracking torque of concrete roof as open section and this error is within 10%. Without considering the reduction of the tensile strength of concrete under twisting, the value of calculation which came from’composite bridge design and construction criteria’ is than the value of test lower 10%.(5) The ultimate torque method of the steel webs (board)-concrete composite box beam has been proposed. This method references to the ultimate torque calculation method of concrete box girder. And it also combines of finite element analysis and test analysis. The ultimate torque which used the methods of this paper is close to the result of test or finite element, and which error is within 10%.(6) This paper takes the Yingjie Bridge as the research object, and builds the finite element model of Midas/Civil 2010. Calculate the torque of the normal limit and the ultimate limit under the load combinations role. And verify the results which used the methods of this paper. Checking the results meet the requirements of torsional properties.