Application Of The External Per-stressed Technique In Bridge Reinforcement

External prestressed concrete structure is the branch of the unbonded prestressed concrete structure.It is the structure system which the prestressed steel is located outside the concrete section for longitudinally completely exerting the pre-stressed. External pre-stressed structure system is different in traditional interior unbonded pre-stressed structure,the interior unbonded pre-stressed steel is arranged in passageway reserved inside the structure.Although on each section the strain of the pre-stressed and the concrete is uncoordinated,But the relative position of the pre-stressed steel on the section is invariable, along the direction of the beam length.It has nothing to do with the deflection of the component.But in external pre-stressed structure system the place of the changes block and anchor relative to the section of concrete beam is invariable,In other position the section eccentricity moment of pre-stressing is changes with the variety of the component,From this it has in external pre-stressed two effects.As a result of two effects existences,In external pre-stressed Beam's carrying capacity, the rigidity, the frequency and it's the crack width and the development on is different has the unbonded or interior pre-stressed structure.In view of this question, this article mainly use general finite element software to research to external pre-stressed structure, and get some conclusion:(1)Introduced the composition of the external prestressed concrete structure,the commonly external pre-stressed reinforcement method and the construction craft,external prestressed concrete structure reinforcement design and calculates(the supporting capacity,deflection and so on), and has made the analysis, the comparison and the summary to each kind of theory and the method existence prominent question by the example.(2)Discussed the stress-strain relations of the concrete structure material and steel bar, the concrete destruction criterion, in external pre-stressed non-linearity various factors. Discussed the question of the modelling method of ANSYS,the unit choice,convergence and so on, obtained some significance the conclusion.(3)By ANSYS, mainly studies the work mechanism and stress performance of simple beam reinforced by external pre-stressed.(4)Finally carried the summary and forecasted the complete paper work, proposed the question which be worth research in the future.