Study On Prestress Increment And Reinforcement Design Of Externally Prestressed Concrete Structures

In the field of bridge construction, the application and development of external prestressing technology has experienced a very long process as a branch of prestress technology. It inherited the excellent performance of the traditional prestressed concrete structure, but also greatly simplify the construction process. With the development of the antiseptic technology, breaking the limitation of the technology on the durability of Bridges, makes the external prestressing technology in concrete has been widely used in bridge construction and reinforcement. Compared with bonded prestressed structure in the body, the biggest difference of external prestressed structure is the deformation of externally between prestressed tendons and structural deformation. So the size of external tendon stress increment for structure design and calculation is a very important research content. This article mainly study the method of calculation of the externally prestressed tendon stress increment and externally prestressed reinforce concrete bridge.Firstly, By studying the present study of the external prestress increment, we find that closely related to stress increment and structure geometry deformation. At home and abroad method based on the deformation of structure stress increment can achieve good accuracy. Mostly for straight girder bridge, however,it is not applicable for curved girder bridge. Based on the deformation characteristics of the curved bridge and the influence of curvature, author establish the formula of external prestress increment based on geometrical deformation. And analyzes the influence of the external prestress increment on the different bending degree.Secondly, for the exists nonlinear of externally prestressed concrete structure, the calculation of the stress increment of precise must consider the influence of nonlinear. The author adopted the model considering the tensile players and proposed the analysis method of the whole process of externally prestressed concrete structure. Combining with pre-stressed bending test in Singapore, author compile calculation program Using the Visual Basic process. After comparing with the experiments, we found it achieve good accuracy.Lastly, based on a continuous rigid frame bridge,except for the disease problems of the bridge,the author uses external prestressing technology to reinforce and evaluate the effect of the reinforcement. It shows that imposing external prestressing bridge in service can inhibit girder across middle scratched and improve performance of the bridge normal use.It has obtained the very good reinforcement effect.