Analysis Of The Mechanics Performance Of T-beam Bridge Strengthened By External Prestressing Tendon

External prestressing technique which is one important branch of post-tensioned prestressing system, can be used for building, rebuilding, transformation and reinforcement project. External prestressing technique which is a kind of active reinforcement method, can improve the component's abilities of bending resistance and shear resistance. The project examples adopt external prestressing technique to strengthening and reforming the old bridges at present is countless, but most analysis is according to current standard and elasticity theory. The in-depth research on nonlinear analysis of bearing course of strengthened bridge, especially the ultimate load carrying capacity is not enough.This article's background is a urban highway bridge which was strengthened by external prestressing because of requirements of the upgrade of traffic load. By the use of large scaled finite element analytical software ABAQUS, the author creates finite element models of nonlinear analysis of external prestressing concrete bridge. Nonlinear effects of material, geometry, boundary conditions are taken into account in these models. The author has analyzed behaviors of T-beam bridge under dead load and redesign load before and after strengthened, evaluated bridge strengthening effectiveness, calculated the ultimate loading capacity of bridge, discussed the effects of friction coefficient, effective prestressing force and the area of prestressing tendon on behaviors and the ultimate loading capacity of bridge.The results of analysis show that effectiveness of bridge strengthened by external prestressing is remarkable, the stiffness, ability of bending resistance, work performance and ultimate loading capacity of the bridge strengthened by external prestressing are significantly improved. If friction coefficient value is bigger, the stiffness, work performance and ultimate loading capacity of the bridge are improved more significantly, but the stress difference of prestressing tendon is bigger. With the increment of effective prestressing force, the stiffness of bridge, the cracking load of the concrete, the yielding load of the general steal bar and the ultimate loading capacity of the bridge are improved in varied degree. Under the condition that tensioning force remains constant., if the area of prestressing tendon is increased, the ultimate loading capacity of the bridge is improved, but the cracking load of the concrete is reduced.