Finite Element Analysis To Deviator And Design Of Continuous Rigid Frame Bridge Strengthened By External Prestressing

There are many technical innovation and renovation in the prestressed concrete continuous rigid frame bridge's development history. The familiar deteriorations such as cracks in concrete and large long-term displacement have been happened in a few years after the construction.It is pointed out the deteriorations of long span prestressed concrete continuous rigid frame bridge and the corresponding strengthening measures to the load carrying capability of the structure and cracks in concrete. Then it is briefly summarized the characteristics and the basic structure of external prestressing system, as well as the design principle in strengthening existing concrete bridges by external prestressing. Considering that it is the most important and key part in external prestressing concrete structure, and the design of deviators is directly related to serviceability and durability of structure, the performance of deviator is analyzed in this paper in detail.The Guangzhou Dongpu Bridge has been used in this paper as an example to analyze the cause of deteriorations and the rationality of external prestressing way to strengthen the prestressed concrete continuous rigid frame bridge. It is also briefly introduced the principle and method of Finite Element Method to analyse concrete structure. The deviator in first span is chosen to analyze the stress distributions by finite element method. The calculation is carried out from the whole to the part, that is, at the beginning we use the plane software to calculate the forces, and then use the FEM to analyze the deviator in detail. This way greatly improves the efficiency. The calculation results show that the external prestressing affects the bending stress most efficiently. The stress concentration appears between the deviators and bottom plane. The design to external pretressing strengthening must avoid the hole of deviators close to the bottom board excessively resulting in concrete cracks . In order to reduce the weight of deviator, echelon piece is brought forward whose upper part is small as the result of optimal design.