Application Of Externally Prestressed In Continuous Girder Bridge Reinforcement

Since China’s reform and opening up, the road and bridge construction has been rapid development. China’s construction of road and bridge played a key role in creating a good investment environment, and promoting regional economic development. Comparing with constructions of roads and bridges, maintenance is thought to be more important in the whole service life. Since the beginning of the new century, China’s economic take-off make traffic far beyond the expected growth rate, the bridge carrying ability, width cannot meet the needs of vehicle operation. The loads of highway bridges fall far beyond the original design stage to predict burden values, therefore bridge bearing capacity generally inadequate. Additionally, with the old bridges aging themselves and their damage, there is a substantial reduction the service life of the bridge. A severe situation has formed in the engineering constructions of highway traffic. Disease of highway bridge cannot be ignored. Takeing appropriate reinforcement measures is particularly important, so as to ensure the smooth passage of highway traffic.This paper introduces the common reinforcement methods of bridge superstructure, and construction technology, advantages and disadvantages are illustrated as well as the scope of application of various reinforcement methods. In this study, external prestressing reinforcement methods was conducted in-depth research, which is an important branch of post-tensioned system. The principle of external prestressed bridge is the use of a section of the internal force of prestressed reinforcement generated to offset some or all of the constant cross-section at the controls, live load pulling. to control the offset or all of the dead and live load. In essence, prestressing reinforcement is used to unload the structure control section. After reviewing relevant literature, design specification and experimental data abroad, relatively reasonable equation for ultimate stress increment of prestressed tendons is proposed. Moreover, calculations of reinforcing bending section force, shear strength capacity and prestressing tendons loss in vitro are also discussed.In this study, a bridge project is taken as a case study. Many monitoring mehods are carried out on this bridge, such as visual inspection of bridge structures, concrete strength, static load load test, and dynamic test. In order to fully understand whether the characteristics of the beam current state of technology can meet design and bearing capacity requirements. At last, by using Bridge doctor(commercial software) to calculate the stress analysis before and after strengthening reinforcement as a comparison, a reasonable bridge strengthening measure are put forward. Besides, by comparing the in vitro effect of prestressed reinforced concrete bridges, the carrying capacity of the bridge is improved, which provide reference for the actual construction of the project.