The Analysis Of Disease And The Study Of Strengthening With Cantilever RC Box Beam Bridge

With the development of the nation's economics, the traffic amount increases rapidly and the loads of the bridges bearing more and more aggravating. Considering the factors of design, construction and age etc., a lot of bridges have been damaged over the days, their carrying capacity and stiffness have been get down. Therefore, detection, assessment and reconstruction for existing bridges has become one of the most important problems that are being discussed by engineers. With the example of YongJiang Bridge, the analysis of disease and strengthening are studied for double cantilever RC box beam bridge as follows:The detection, assessment and analysis of diseases were studied for old Bridge, and targeted the YongJiang Bridge was analyzed. As the design analysis showed that the "shear lag effect" considered insufficient, inadequate inclined section shear, overloading of vehicles, and so on, which caused the joint of flanges and webs damage early, extended on both sides of the flange and web, made through crack. At the same time, some expansion joints and deck pavement were damaged, with the impact load in the vehicle and the role of fatigue, the beam of disease further intensified, leaded to the bridge structure carrying capacity and stiffness of the overall decline.A strengthening method for double cantilever RC box beam bridge "Pre-stressed steel truss integrated strengthening" was proposed. The programme has obvious advantages in structural damage, traffic impact, construction difficulty, bridges handsome and reinforcing effect (stress, displacement), etc. Bridges reinforcement must be considered the characteristic that bridge bore different load in different phases. The design should distinguish the nature of reinforcement and clear purpose of reinforcement. Through the reasonable simplification and assumptions, the paper analyzes and compares the result of reinforcing effect in force and modal with the method of finite element, the result verifies the reasonableness and notes that uninstall strengthening can further improve the situation and increase the use of reinforcement materials efficiency.