Application Of The External Pre-stressed Technique In Concrete Bridge Construction

External prestressed concrete structure is the branch of the unbonded prestressed concrete structure. In external prestressed structure system, the place of the changes block and the anchor relative to the section of concrete beam is invariable. In our country, the study and application of this new technique are almost limited in existing bridge's strengthening, mechanical behavior studies and applications of new concrete beams prestressing with external tendons still lack very much. Based on design and construct R20#-25# beam of JinTang crossroads bridge of TianJin city high way, the following aspects are investigated:1.Reviews the developing history and present status and explores the constitution of external prestressing systematically. Introduce the component of prestressed concrete structure and fatigue properties reinforcement beams, anchor systems and the loss of prestressed.2. Research factors which influence endurance of external prestressing concrete bridges, and then presents measures and suggestions for enhancing it.3. Based on design and construct R20#-25# beam of JinTang crossroads bridge of TianJin city high way,Summarized its construction main point, has provided the reference and the model for the next bridge construction control.4.Finally carried the summary and forecasted the complete paper work, proposed the question which be worth research in the future.