Research On Dynamic Reliability Of Cracking RC Bridge

In recent years, it have got Rapid developed of transportation industry in China, The national highway system was gradually perfected. Concrete bridge construction also got greater development. As the growth of the Reinforced Concrete bridge service time, it is different types of cracks that the Reinforced Concrete bridge have appeared. the Reinforced Concrete bridge crack seriously affect the bearing capacity and the durability of the bridge. At the same time because the bridge accidents have were occurred in recent years, The growing of the bridge crack is considered to be premonition of the bridge damage. Everyone will have strong feelings of fear when the bridge cracks were happened in the bridge. It is very important theory value and practical significance that researching on dynamic reliability of the Reinforced Concrete bridge with crazes and residual life prediction for the Reinforced Concrete bridge with crazes. It can be provided the theoretical basis for the management of the cracks, When the crazes of the Reinforced Concrete bridge were serviced.This article based on the development of science and technology program of Transport department of Fujian province——researching on the concrete bridge with crack countermeasures and the key technology of preventive construction from Fujian province. It is a engineering example that simply supported T beam bridge that is with the cracks, it is studding that load effect and resistance attenuation model of the Reinforced Concrete bridge with the cracks though the example. Based on the checking point method(the JR method), we can calculate the dynamic reliability of the Reinforced Concrete bridge what is cracking. Then it was discussed that residual life of the bridge according to the result of the dynamic reliability. In this paper, the main work content is as follows:1. According to the results of a survey of cracking in concrete Bridges in service from the Transport department of Fujian province. We analyzed the distribution of all kinds of concrete bridge crack;(1)Cracking of Reinforced Concrete T Beam Bridge is mainly two longitudinal cracking which are flange plate diagonal cracking and flange plate and web plate junction longitudinal cracking, which are support span, 1/4 and 1/5 oblique crack near.(2) There are three main kinds of crack form the reinforced concrete small box girder bridge. they are Bottom longitudinal cracks and transverse cracks, Transverse cracks of box girder wet between the joint, vertical cracks in Beam cast-in-site segments.2. Based on the basic principle of reliability, this paper introduces the dynamic reliability theory. According to an engineering example, the paper set up the dynamic model of concrete carbonation depth and the dynamic model of reinforcement corrosion over time, based on the theory of the dynamic reliability. The paper established the dynamic model changeover time of the reinforced concrete simply supported T beam bridge with the cracks,load effect and resistance attenuation dynamic model change over time, discussed the structure reliability of the law of the change over time with considering the effects of cracking of reinforced concrete simply supported T beam bridge3. Using 2014 a mathematical software MATLAB to write the program to calculate the dynamic reliability index with checking point method(JC method). To calculate the dynamic reliability calculation of simply supported T beam bridge with the cracks, and to forecast and analyze the residual life of the cracking simply supported T beam bridge according to calculate the dynamic reliability index. In the same time, the dynamic reliability of the overload operation smaller than the normal load operation, and it is faster that the dynamic reliability decline rate of overload operation, and make the service life of the reinforced concrete bridge structure greatly reduced. At the same time and same operating condition, The more bridge cracking, the smaller the dynamic reliability of RC bridge structure. The smaller the dynamic reliability of RC bridge structure, the shorter normal service life of the reinforced concrete bridges, and it will be a seriously affect for the bridge construction and the traffic network plan.4. How to identify the crack of the concrete structure is the key to deal with crack problem. Only to correctly judge the various causes of cracks and the influence degree of the cracks of the bridge structure, It is correct that the judgment of the nature of cracks and its influence on structure safety and function. In this paper Finally, it is putted that some measures to prevent cracks and some methods to repair the cracking Bridges, according to the view of the dynamic reliability of the RC Bridges in the former in the paper, puts forward some prevention measures and cracking of concrete bridge cracking after repair methods.