Theoretical Research Of The Reliability Of Prestressed Composite Space Truss Based On The Overall Ultimate Bearing

Prestressed composite space truss (PCST) is a kind of new prestressed large span complex spatial structure system composed of steel and reinforced concrete, which is developed basing on composite space truss and prestressed technology. It can play strength advantages of two different material, with great overall stiffness, high bearing capacity, good seismic performance. However, due to the complexity of the constituent materials and diversity of structural elements of the PCST, the whole process of the entire structure beyond the elastic limit, entering the nonlinear achieving the ultimate bearing capacity resulting in the damage of the structure is short of effective analysis method. The PCST as a highly indeterminate space structure,, it won’t lose bearing capacity with its part into the plastic. The more reasonable design method should be based on the overall analysis of the ultimate bearing capacity of the structure and to ensure that the whole structure bearing state reliability as the objective. In this paper, the reliability of the prestressed composite truss structure based on the ultimate bearing capacity is studied, the main work as following:In order to accurately simulate the nonlinear response of the whole process of the PCST bearing load, tracing the development process of its damage and the overall ultimate bearing capacity, a large scale analysis model of prestressed composite truss structure is designed on the basis of relevant specification, and use solid element, bringing into a single compressive rod mechanical model, a more close to the actual stress finite element numerical model is built.On the basis of this model, it carries out typical dual nonlinear overall ultimate bearing capacity analysis, tracing whole process of the nonlinear force of the major components, so that obtain the stress process and force characteristics of each of the main components, determining the structure failure mode and the ultimate bearing capacity state.Analysis shows that the failure mode of the PCST is mainly concrete plate crushing along the diagonal area causing structural damage.It gets the ultimate state function of the structure based on the structure failure mode of the PCST, and selects the parameters of the structure, which the function is greatly influenced by, and carries structural reliability analysis with the use of the Monte Carlo method in ANSYS.Then, it obtains the approximation reliability index of the structure, each input variable sensitivity for function, giving the method of increasing structural reliability.