Experimental Study And Theoretical Analysis After Fire-resistant Property Of Prestressed SRC Beam

The prestressed steel reinforced concrete structure is a new type of composite structure, which places prestressed steel in reinforced concrete, making four kinds of materials including prestressed reinforced steel, section steel, ordinary reinforced steel (longitudinal reinforcement and stirrups), and the concrete in coordination to resist the external effects. Compared with ordinary concrete structures, the prestressed steel reinforced concrete structure combines the advantages of prestressed concrete structures and steel reinforced concrete structure. It can effectively retard crack development, reduce or even eliminate the deflection of the component under the working load, improve the carrying capacity and stiffness of the structure. Therefore, the prestressed steel reinforced concrete structure has a broad prospect of application in the span structures, overloaded structure, and high-level, super high conversion structure.In this paper, the prestressed steel reinforced concrete simply supported beams are researched about its bearing capacity under and after high temperature by the fire, discussing the impact of the performance which made by the factors concluding fire time, prestressing degree, protective layer thickness, etc. The main research contents and main results are as follows:1. Through the bearing capacity test of the prestressed steel reinforced concrete simply supported beams under the fire and load coupling, it analyzes the contents of component internal temperature distribution law, end of the pre-pressure variation and characteristics of component destruction, etc, reveals the deterioration mechanism of prestressed steel reinforced concrete simply supported beam’s mechanical properties in the high temperature.2. Through the bearing capacity test of the prestressed steel reinforced concrete beam after fire and high temperature, it analyzes the factors of fire time, prestressed degree and protective layer thickness impact on crack development law, deflection change of law and bearing capacity degradation of the prestressed steel reinforced concrete simply supported beam after fire.3. Based on the finite element method, the normal section flexural strength calculation formula of the prestressed steel reinforced concrete simply supported beam is established after fire high temperature. Compared with the experimental results and the calculation of the effective section method, it coincides well.4. Based on the cracking moment and crack width calculation theory of prestressed steel reinforced concrete simply supported beam under normal temperature, the calculation formulas of cracking bending moment and crack width on the prestressed steel reinforced concrete beam are established after the high temperature, considering the effect of high temperature influence on the performance of the materials.