Externally Prestressed Beam Bridge Strengthening

Along with time pass and economic development more and more bridges do not meet the needs of the traffic. It will consume very huge fund to dismantle and rebuild such bridge, it is impossible too. Bridge consolidating is a good solution for solving these problems. For bridge consolidating this hot question, bridge consolidate method is studied in this paper. Now the method of consolidating bridge is especially much, this paper summarized and analyzed the methods of consolidating that suit beam type bridges, for example: add bridge floor thick method, increase beam rib method, paste steel plate method, paste fiber material method, prestressed external tendons method, change structural system method, and introduced the respectively principle and characteristic of each consolidate method.This paper careful studies the prestressed external tendons method. This method is put prestressed external tendons outside the bridge's body, tendons anchor firmly in bridge beam two ends, and exert axial pressure and curve to beam. Because the curve produced by the tendons is opposite to the original beam adverse curve in direction, can offset the stress of dead weight and reduce the stress of live load, raise the bearing capacity of beam. This kind of method of consolidating effect notable, side effect is little, and can reduce or avoid crack, raise the endurance of beam, can resume or raise the load grade of bridge, need not chisel to exclude concrete covering layer, damage beam body level is little, do not influence or less influence traffic when consolidating bridge, it is a better bridge consolidate method.The new code for highway bridges promulgate and implement need carry out new research for consolidating of prestressed external tendons method. Contrast highway new code , this text did structure analysis and mechanic analysis for prestressed external tendons bridges consolidate method; presented the calculation method for mechanics and virtual solutions;presented the calculation method for stress, deflection and crack of normally using stage for consolidated system; presented the calculation method for extremity strength of consolidate system.Using the result compared the method of consolidating for a actual bridge. When the consolidating method is determined, this text designed and calculated the example calculation, and have made verification with bridge professional software(GQJS),:and gave the common construction technology for prestressed external tendons bridges consolidate method; made structure analysis and mechanic analysis for deviators which as a part of prestressed external tendons bridges consolidate system, and give the design calculation method for deviator.