Research On Time-varying Model And Bearing Capacity Of Corroded Concrete Filled Steel Tubular Members

Concrete filled steel tube is an excellent combined material, the fragility of concrete is restrained with the confinement of the steel tube wall, so the compressive strength and deformation capacity of concrete is improved. Especially in arch bridge, the contradiction of hoisting weight and span can be solved by the CFST material. CoMPared to practical engineering, the corrosion of CFST members is a serious problem among them.This paper relies on the topic of Chongqing Natural Science Foundation Project——"the corrosion of concrete filled steel tubular members of time-varying model and bearing capacity decay rule", theoretical and numerical analysis are deeply carried out. The main research results are as follows:The time-varying model of uniform corrosion is proposed, the application results show that this new model is in good agreement with the experimental results.Based on probability and statistics theory, the pit corrosion relation in different time point is carried out. The SCC model is established by the theory of fracture mechanics. Stress function is constructed with the equilibrium equations of local corrosion of steel tube. The displacement field and stress field of SCC model are analyzed, the classical crack initiation criterion and crack propagation velocity are modified.For uniform corrosion of, the ultimate bearing capacity considering the different corrosion depth, different initial are calculated. The results show that:corrosion depth increases, the capacity reduces. Moreover, the regression formula is fitted.For local corrosion of CFST members, the ultimate bearing capacity considering the different corrosion shape are calculated. The results show that:the corrosion pit will greatly weaken the ultimate bearing capacity of members; corrosion pit depth increases, the capacity decreases. The pit depth also significantly affects stress development.