The Study Of The Cause Of Girder Crack And Prevention And Cure Countermeasure In Collaborative Concrete Cable-stayed Bridge

Due to its economy, stability and the relative facility of construction, cooperative prestressed concrete cable-stayed bridge has been widely selected when building long-span bridges.However, the crack problems in the process of concrete bridge construction and operation period have been the important problems, this paper studied on this question.In this paper, we focus on one bridge, a cable-stayed bridge of cooperative system with a single tower. Using finite element simulation analysis finds out the reason causing its fracture. In this paper, following work has been done:This thesis makes a survey of the cracks in one particular bridge through conducting experiments and tests, and finds that cracks appear most in number and severity in the cooperative span and non-cable main span, especially in the areas of the web and bottom slabs.Using the software Midas Civil for finite element analysis, a model of the whole bridge is built to simulate the construction process of the bridge, analyze its stress level respectively upon completion and while in operation, and study the loading characteristics and weak areas of this type of bridge on the whole. Based on the findings, the thesis interprets the typicality of the places of cracks in the prestressed concrete cable-stayed bridge with cooperative spans.Apart from the full-bridge model generated by Midas Civil, drawing from the model, the thesis examines the contribution of each factor to the formation of the cracks, including factors like temperature, foundation settlement, concrete shrinkage and creep, vehicle load, and then determines the most influential factors as well as the extent of their influence. Based on the above studies, the thesis concludes that temperature and the overload of cooperative spans on both sides are among the most important contributing factors of cracks in cable-stayed bridges of cooperative system.Using the Finite element analysis software Midas FEA to establish local finite element model, taking into the material nonlinearity of concrete and steel, we analyzed the stress state of the main beam of a variety of factors. The study results showed that: on both sides of the section across to the pier, there was greater main tensile stress on the girds web under the effect of temperature and overload.The crack position and the actual test results are consistent to the actual test results. This thesis carries significance to future studies of the causes and control of the cracks in the concrete cable-stayed bridge of cooperative system.