Study Of The Residual Load Bearing Capacity Of Steel-concrete Axial Compression Columns After High Temperature

The mechanics of the members after high temperature are the premise and basis of the service and reinforcement of the structures after fire.The steel reinforced concrete column has the great reiforcement value because of the protection of the peripheral concrete to the internal steel .Therefore the study of the mechanics of the steel reinforced concrete columns after high temperature has great practical value. main contents of this paper are as following:1.The temperature field distribution of steel-concrete composite sections under standard fire including of temperature rising and decreasing is analysed ,and the highest temperatures that all nodes are calculated,The calculated results are verified by some test result. At the same time, calculated results based on the combined boundary of convection and radiation are compared with that of comprehensive convection boundary.2.Strength-damaged model and stress-strain model of steel and concrete exposed to fire were selected reasonably on the basis of summarizing and analysing the mechanics of steel and concrete used in RC structures and steel structures domestic and abroad. Rationality of the model and the theoretically analysing method has been verified by corresponding experiments.3.The steel-concrete axial compression member's load-deformation curve after fire is obtained by using ANSYS finite element method. The mechanics of steel-concrete axial compression member after fire are understood well after a great deal of parameter analysing work was done.Based on the research in the paper,conclusions are as following:(1) thermal properties have big influence on the temperature field of composite sections, and results from the two ways mentioned above have little difference.(2) The steel and concrete's stree-strain models suggested here is suitable for finite element analysis of the mechanics of steel-concrete axial compression members after high temperaures. Using this method, the complete load-deformation curve of the members after fire can be obtained accurately.(3) On the basis of a great deal of parameter analyses, the important factors influening the load bearing capacity influence factor of steel-concrete after fire are found.