Research On Remaining Service Life Forecast Of The Strengthened Bridges Based On Dynamic Reliability

China began its large-scale infrastructure Since the Chinese Economic Reform, and hasmade tremendous achievements. Until the end of2011, China’s highway mileage has reached85,000kms. As for traffic control projects, bridges play an important role in the highway andrailway construction.With the growth of the structures’ service life, the damage of structures is unavoidablewhich will cause the bearing capacity of inadequate and reliability decreases, because of thestructural material strength degradation and its surrounding environment. In order to makereasonable decision on the damaged bridges, we have to do a lot of work on appearancedetection, capacity assessment and on fixing the dynamic reliability, and gathering experiencefor the same type of bridge structures.In this thesis, the research object is a PC Simply-supported Hollow Slab Bridge. As abridge structure in the form of practical, with the advantages of simple structure, easyconstructed and lower building height, has been widely used in the field of Small andMedium-sized Bridges in China’s highway construction. Firstly, the damaged condition isexamined，in order to make sure the disease and the real strength of the material is known,then, the preliminary quantified assessment of the reliability and the carrying capacity aredetermined, finally, the thesis reached the conclusion that the bridge needs reinforcement andrepair.By summing up the advantages and disadvantages of the usual structural reliabilitycalculation theory and methods，this thesis presents an easily popularized method of reliabilityin view of the complex factors on bridge structure reliability calculation. The analysis of thedamaged bridge shows that the shear capacity is seriously inadequate, so the bearing capacitylimit state is selected to establish a performance function. The random number of structureresistance and load effects can be generated via Matlab, and the BP neural network can becreated by the Toolbox which born from Matlab. After pilot calculation, the trainingparameters can be determined and the BP neural network can be trained, while the explicitexpression of the bearing capacity limit state will be appeared. In the end, JC method is used to calculate the reliable indicator. The following30-group checking demonstrates that usingthe method to calculate the accuracy of the complex structures is of reliability and practicality.The end of this thesis presents brief introductions about analysis on the reinforcementprogram to determine the Comprehensive-reinforcement Measure. The structure resistancemodal is modified according to the reinforcement program，then the reliability of thereinforced bridge is available，which can prove that the reinforcement program is effectiveand reasonable, and the remaining service life of the reinforced bridge is forecasted byanalysing the whole process dynamic reliability.