Evaluation And Analysis On Strengthening In Externally Prestressing Of Bridges

Because of the advantages of simple construction, structural safety and economy, the external prestressing technique has been widely used in the new construction of bridges. Also, Many bridges at service are suffering from crack or over distortion due to corrosion of reinforcement bar and overweight. It is very effective to strengthen these structures using the externally prestressing technique.According to the present experiment beam of external prestressing.This article mainly analysis the different simplified formula to the ultimate stress of external prestressing tendon on the base of theoretical analysis. Influence of various parameters including ratio of unprestressed reinforcement, ratio of external prestressing tendon, span-depth ratio, compressive strength of concrete, and loading pattern on the ultimate stress in tendon, fps, are investigated in detail. Parameters having important influence on second-order effects of externally prestressed concrete beams as deviators, tendon configuration and load type are evaluated. Then it can find almost suitable calculated formula of the ultimate stress.In this foundation, then reconsiders the safety coefficient to the bridge design.So it can be used to instruct the design of externally prestressed beam.Through analyse the pressed characters of reforced system within external prestressing,It evaluated the calculational method of normal cross section flexural bearing capacity and normal cross section flexural bearing capacity within reinforced system.Also,it evaluated the calculational method of stress increment of external prestressing tendons,stress deformation and deviator are used.Moreover,It put up separated computations by reinforced examples of RC beams and PC beams.according from the result of checked calculation, reinforce computational method of vitro pre-stressed is recommended by this article. It's more ideal reflect that the beam's stress situation after has used in vitro pre-stressed reinforcement.The goal of this article's calculated demonstration is that for reinforce the supporting. Also it may used in reinforce method of vitro pre-stressed to reinforce the instructed durability and using.function.