The Research On Rotational Stiffness Of External Steel-Concrete Composite Truss Joint

Abstract:Steel-concrete composite truss structure is widely used in building and bridge field for its superior mechanical properties. External joint has the advantages of light weight, high stiffness and excellent overall performance characteristics. The rotation of joint which caused by local deformation of joint under load is neither the same as hinge nor the rigid connections, and it also have appreciable impact on the deformation and mechanical behavior. But related researches on rotational stiffness were rarely mentioned in domestic.On the basis of existing model experimental results, this paper focuses on the finite element analysis to research the rotational stiffness of external truss joint. The main results are as follows:(1) Establishing a external steel-concrete composite truss joint model by applying finite element software to simulate the force state and deformation under horizontal loads. Contras of finite element analysis and experiment results verified the correctness of the model.(2) Further research on rotational stiffness of external steel-concrete composite truss joint. This paper analysis the stress magnitude and distribution of joint under the in-plane bending moment base on separate analysis of each component object and focus on the influences of rotational stiffness by gusset plates.(3) Parameter analysis is carried out to research joint’s rotational stiffness and it holds that the ratio of width and thickness of ventral pole, the angle between truss chords and ventral pole, the ratio of height and width of ventral pole, and the thickness of gusset plates had a significant effect on the rotational stiffness. What’s more, making use of linear regression methods to obtain rotational stiffness formula and the scope of application is given.(4) This dissertation established the finite element model of steel-concrete composite truss bridge with the consideration of initial rotational stiffness impact. Besides it also analyses the influences on secondary stress, internal forces and deformation to get the result that it’s necessary to consider the impact of rotational stiffness when calculate the internal force of ventral pole.