Experimental Research And Analysis On Load-carrying Capacity Of The Existing Prestressed Concrete Girder Bridges

At present, prestressed concrete highway bridges are used widely in China. Almost all of these bridges have some damages because of design, construction, deterioration of material, environment and many other factors. There are some bridges which are designed according to lower designing grade. These bridges have more and more problems of safety along with the advancement of the highway development. The key problem to utilize those bridges properly is to research the degree of deterioration, the potential capacity of load-carrying, the degree of reliability and etc.It is of great theoretical significance and application value to refinedly analyze prestressed concrete girder bridges. Refined analysis includes researching the deterioration reasons, studying the ultimate performance, analyzing the behaviors in the lifetime by nonlinear spatial finite element method, evaluating the reliability of load-bearing capacity, and so on.The main content and results of this dissertation are as follows:(1) The deterioration and crack reasons of the PC girder bridge were systemically analyzed. The behavior of the corrosion of the steel bar was also studied. The damage reason of hollow plate girder, T-girder bridge and box girder bridge was also researched in details.(2)At present, there are few full scale destructive tests of the PC T-girder bridges and PC box girder bridges home and abroad. This dissertation has did destructive experimental study of ultimate load-carrying capacity on the Xin Xing Tang main bridge and Xi Cheng River Bridge. Xin Xing Tang is a 3-span PC continuous girder bridges with the main span of 50m. Xi Cheng River Bridge is a simple supported T-girder bridge with the span of 20m. The two bridges are all on the highway from Nanjing to Shanghai. The project itself has a great deal of innovation.The destructive character and theory, and the whole destructive procedure of the two common bridge styles have been firstly refinedly researched by full scale destructive tests on site. The results can help us to understand and master the structure rigidity, restoring force character, destructive state and load-carrying capacity of the concrete girder bridge under service load and ultimate load.Many assistance experiments have been done also such as bridge viewing examination, destructive and nondestructive detection, static test and so on. Distributed optical fiber sensors were exploringly used to detect the crack of concrete bridges.(3) Xin Xing Tang bridge was analyzed under the testing load by nonlinear spatial entity finite element method. The FEM software ANSYS was used. The analysis results were compared with the test. The applicability of the analysis method was proved. Some parameters which affect the load-carrying capacity and deflection of concrete bridge were analyzed and compared. These parameters include grade of concrete, rust of tendon, loss of prestressing, the thickness of Pavemen and so on.(4)The modified method on dead load and vehicles load were discussed based on the character of the load on the concrete bridges. The statistical formula of the maximum vehicles load was deduced according to the fact that random variable is extreme value I distribution in one year. Probability model at present was...