The Structure Analysis Of Continuous Beam Strengthened By External Prestressing And The Research Of Anchorage System

There is various damage causing by multifarious reasons in bridge structure during long-term use. Especially, the traffic environment become increasingly severe, there are more or less different extent disease and cracks. At the same time, the load grade of design code in old bridge is lower. As an result, more and more bridges don't adapt the demands of current traffic. So the bridge rehabilitation, which can improve the carrying capacity of bridges, is one of main methods to figure out this problem and become a hot issue in engineering.There are several methods of continuous beam bridge rehabilitation in common use, such as thickening of bridge deck, widening of girder rib, bonding steel plates, bonding FRP, the external prestressed rehabilitating and changing structure system.It is necessary to discuss and study new technique and method of beam bridge rehabilitation in that the former prestressed beam bridges account for quite high proportion among traffic system in our country. The external prestressed rehabilitating becomes the first selected especially in large span bridge and multi-span bridge structure due to its light weight, initiative, high efficiency and strong adaptability.The test results, including the external prestressed rehabilitating design of large span bridge and multi-span bridge, can benefit the construction engineering. Especially, the comparative analysis and the improvement measures in reinforced concrete anchoring system, have reference value for the anchoring system design in the external prestressed rehabilitating of bridges has box girder section.This paper studies the using performance of Shiqiao Sanqiao bridge in three phases including the construction stage, the operating stage to now and strengthening stage by external prestressing. The steps and value calculation of external prestressed rehabilitating design are obtained in quantity, and the mechanical analysis of prestressed strengthening system is also presented. The finite element method analysis is used to develop the external pretressing anchoring system. The influence of size and location under the action and the types of external prestress on the stress distributing in the box girder and the anchor block is studied. The assistant components of strengthening, which of advantages and disadvantages are discussed, are used to improve the anchoring system.