Prestressed Composite Truss Ultimate Bearing Capacity Analysis

Prestressed composite truss is a prestressed space structure of the new system,which is developed basing on the technology of the layer truss and prestress by the combination of the steel and reinforced concrete.Currently, in this field of research and applications are very little.In this paper, the ultimate bearing capacity of the prestressed composite truss of were analyzed through building a three-dimensional nonlinear finite element model.Summarized, the force and failure modes of prestressed composite truss are more reasonable, which ane worthy of a space structure system.In this paper, three-dimensional nonlinear finite element model is established baseing on the material and geometric nonlinearity,which can simulate concrete cracking, belly bar, bottom chord and steel yielding, buckling of compression web member of the destruction of the development of other components process. Also a method of the optimal prestress value of the prestressed composite truss is proposed.Compared with the experimental results verify the validity of the finite element model.Mumerical examples of the ultimate bearing capacity of prestressed composite truss were given in this paper. Then analyzings the prestressed composite truss failure mechanism of each component.Analysis showed that the combination of prestressed cable grid to improve the limits of carrying capacity and improve the structure of the role of the mechanical properties significantly. Imposed on the PC, the prestressed cable, steel frame (except on the ventral rod bearing connected to outside), the first grid, the panels within a large area bending rigidity, and prestressed cable for composite structures role in the destruction of the concrete slab is different from the normal development of concrete slab, and no plastic hinge appears in the diagonal position, on the contrary, the position of stress is smaller than the corresponding board position Tendon Disposition stress is large.The Analysis showed that the prestressed composite truss had a high ultimate bearing capacity, good ductility and reasonable failure mode; The weakness parts of composite structure was in the first place. The department's plate and cross-section reinforcement rods should be increased when the structural design was did, and ensuring that the slenderness ratio of compression web members.