Study On The Damage Of Reinforced Concrete Bridges Subjected To Fire And Strengthening Method

In recent years, with the rapid development of high-way,.the number of bridges gradually increase, and the number of disaster problems occurring in the process of bridge operation also more and more get people’s attention. The fire has enormous influence on the performance, the safety of the bridge, and it has become the highest probability of occurrence and one of the biggest disaster losses.Bridge structure under different degree of damage after fire, seriously affect the safety performance Therefore, testing the damaged parts timely and scientifically evaluating and putting forward effective reinforcement scheme are very important. Because the cost of the fire test is high and fire simulation is difficult, studying the fire resistance of the bridge by the test can be difficult.In this paper, software simulation is applicated to study the fire resistance of bridge structure, and a typical T bridge is seen as an research example. Through the finite element numerical simulation and theoretical calculation, compared with the actual project cases to analyze its mechanical performance, the testing result of the combined reinforcement suggestion is given. The main contents are as follows:(1) The change rule between thermal parameters of concrete and temperature of steel has been carried on the related research. Through the comparison and analysis, thermal performance parameters which are suitable for reinforced concrete girder bridge in order to analyze temperature field are identified. They have been as the the basis to research reinforced concrete beam section temperature field.(2)On the basis of thermodynamics fundation, this research applies transient dynamic analysis to study the temperature field distribution of multiple beam of reinforced concrete T beam bridges under fire and obtains the distribution rule under the time-temperature curve. Besides, this thesis exlpores the stress-strain status of the concrete of reinforced concrete T beam bridge at high temperature and the deflection of top slab and girder rib to provide a basis for the fire resistance disign of the T beam bridges.(3)The application of finite element software ABAQUS in a fire is introduced, as a case study of reinforced concrete T beam component modeling. The temperature field distribution and the influence factors of high temperature, high temperature stress on the structure and the influence factors of bearing capacity are analyzed. Through comparing with the experimental values, the reliability of the fire problem is vetited by the finite element ABAQUS.(4)Basing on the test results of reinforced concrete T beam bridge after the fire, using abaqus finite element analysis software, and basing on the basic principle of thermodynamics, the transient analysis, the temperature cloud of a reinforced concrete T bridge are analyzed, getting the component section temperature stratification chart. Basing on steel bar, concrete strength, elastic modulus of reduction, at the same time the deflection and bearing capacity before and after fire are analyzed. Comparing the formula to calculate the validation, finally the result after the fire damage identification of bridge and proposals for reinforcement are given.