Analysis Of Bearing Capacity Of Right Section Of Strengthened Reinforced Concrete Beam After The Fire Hazard

With the economic development and the progress of the society, the fire takes place more and more frequently, and the economic losses that it has brought to the mankind has the tendency to increase progressively. The reinforcement to the structure after the fire can make the building go on using, and it is not only economic, but also make the building come into operation as soon as possible, so it is a problem badly in the need of solution. The reinforcement method of augmented cross-section act as a kind of traditional reinforcement method, its craft is simple and has wide adaptability, but its theory for the reinforced concrete component after the fire is not perfect.In this paper ,the analysis and study are carried on the bearing capacity of the right section of the beam which is strengthened by the reinforcement method of augmented cross-section after the fire, the main content is as follows:(1) Summarized the general method of calculating the temperature field of the reinforced concrete structure which has subjected to the fire, and has analysed the temperature field of cross-section of the reinforced concrete beam by ANSYS, then gotten the influence regularity of the temperature field of the beam cross-section ,such as :the time subjecting to the fire ,the cross-section subjecting to the fire ,the size of the cross-section, the thickness of the covering layer ,etc. And gotten the temperature field of the component which has known the size of the beam cross-section and the standard warm-up temperature time.(2) Studied on the verification method of the damage to the concrete structure ,which is caused by the fire, in the range of domestic and international, then the equivalent warm-up temperature time and the residual strength have been confirmed.(3) The thermal characteristics of concrete appeared in domestic and international, and the strength of the reinforced bar & concrete, which were subjected to hyperthermia and cool-down, have been summarized and compared. We found that the thermal parameter of concrete, which were used widely in domestic and international, and the strength of the reinforced bar, which were subjected to hyperthermia and cool-down, are much the same. The strength of the hot-rolled steel of gradeⅠ&Ⅱcan recovery completely when they subject to the temperature below 600℃,but the strength of the concrete ,which has subjected to hyperthermia, is very different. The strength and the elastic ratio of concrete, which were confirmed by the test result of the Fire control Institute of Sichuan, are simple and safe, compared with the conclusions of other document. And characteristic parameter of the component cross-section ,which has known the beam size and the standard warm-up temperature time, was gotten.(4) According to our country's current concrete structure design specification, a simple computing method, which is suitable for engineers and technicians in our country, was proposed ,based on the computing method of the bearing capacity of the right section of the reinforced concrete beam, reinforced by the method of augmented cross-section.(5) Test assessment was carried on a general market, which has subjected to the fire hazard, according to the method, which has discussed in this paper, and the design proposal of reinforcement was proposed.