Research On Theory Of Concrete Fatigue Stress Characteristic Index Base On Long Term Monitoring Of The Reinforced

With the increase of bridge service time, vehicle load and changeable factors of environment, the small defects of the original structure will be accumulating in the form of fracture development along with the service history, which lead to constant damping of structure stiffness and bearing capacity until the bridge lost the service capacity because of fatigue damage. Considering the past development of science and technology, the methods such as the stress and the life curve of key nodes, local experimental experience and apparent phenomenon analysis of crack are often used in fatigue performance analysis of the in-service bridge. But the results are often different from the actual development of structure fatigue. So, with the improve of technology and theoretical technology, bridge health monitoring technology is needed in the analysis of in-service bridge fatigue damage. The monitoring technology starts from stress and strain monitoring information, and along with the analysis of structure fatigue damage to get the fatigue damage and evaluate the security situation of in-service bridge.Base on structural damage theory, this article study fatigue stress of Reinforced concrete bridge, characteristic index of structure and fatigue safety state evaluation of Reinforced concrete bridge starting from monitoring information data processing and the residual strain analysis of structure. So, fatigue identification and safety state evaluation of Reinforced concrete bridge can be made. This paper mainly studies content as follows:At first, getting the standard circular piece of phase of reinforced concrete bridge and the real-time stress characteristic parameters through long-term monitoring data, and taking the structure real-time damage and strain energy equivalent principle factors into account to calculate the effective value of fatigue stress parameter and its transformation tendency.At second, by the application of material residual strain model based on the calculation of fatigue stress parameter, the effect of structure fatigue performance caused by residual strain can be analyzed. And then fatigue rigidity damage model can be built under the real-time monitoring information to get the variance of the stiffness and the fatigue damage development of reinforced concrete beam structure which is in service. And after that, the fatigue stress index parameter values which can reflect the structure fatigue state such as stress index, stiffness index and damage factor index model can be got.At third, based on the research of the characteristic indexes under fatigue stress, this article draws flow chart which can get fatigue stress characteristic parameter values with the monitoring data processing and another feature index computing application flow chart. At the same time, the real-time numerical module and real bridge structure module are used to testify the study which using the monitoring data and the information to get the fatigue stress characteristic indexes is feasible.At last, based on the all the theory analysis above, this article focus on a typical reinforced concrete continuous rigid frame bridge of Yunnan highway—Xiao Xiong Mao bridge to develop the real-time monitoring data processing, get the structure standard cycle stage, compute the effective fatigue stress characteristic parameters, calculate the residual strain model of monitoring data, compute fatigue stiffness attenuation, compute the fatigue damage and use the fatigue stress characteristic indexes. And as the results, it shows that Xiao Xiong Mao bridge is in the initial stage of using and in good fatigue safety state. So,achieving the goal of application of fatigue stress characteristic index based on long-term monitoring.