Analysis Of Reinforcement Methods For Prestressed Concrete Simply Supported Box Girder

Domestic and foreign research on external prestressing in the late 1990 s has been more than a decade, the theory and practical experience have been relatively mature. Domestic also done many of similar projects in externally prestressed reinforcement; Pasting steel plate reinforcement as passive reinforcement, by reducing the stress amplitude of live load, limit the development of the cracks, improve the girder bending bearing capacity, this method is more common, but the body prestressing in the reinforcement design are relatively rare, not made, especially under heavy traffic, overload, advantages and disadvantages of each of three methods for reinforcement in himself involved in the whole process of Guangzhou airport highway bridge reinforcement project, the project according to the characteristics of the airport high-speed small box girder bridge, prestressed drew up the body, external prestressing,and pasting steel plate reinforcement reinforcement way, due to the reinforcement of beam body have the same disease and the construction situation, basic to the comparison of three reinforcement ways to provide a good platform, by comparing the advantages and disadvantages of each reinforcement ways were discussed. Since found bridge diseases,mainly do the following work, 1, structure disease cause analysis; 2, put forward three feasible reinforcement ways and analyzed; 3, construction before the implementation of load test to determine initial working state of bridge spans; 4, strengthening the construction; Load tests are carried out again after 5, reinforcement, which approach is validated by the experiment of reinforcing effect of the optimal, 6, from reinforcement effect, sensors and actuators, cost, construction and maintenance difficulty, compares the merits and demerits of the three kinds of strengthening methods to determine their respective applicable scope, the role of induction, in order to achieve promotion.By comparison with experimental data of the following conclusions: the body prestressed solution process is relatively complex, the construction is difficult, especially the thickening of the part of the web plate at the top of the concrete pouring compaction; External prestressing process complex, tensioning high technical requirements, pasting steel plate plan technology mature, relatively low, low cost and construction difficulty without closed transportation, for the operation condition of the box girder floor slants thin, or big traffic roads should give preference to the approach.But pasting steel plate plan have higher requirements about the quality of the glue, the long-term durability of colloid will greatly affect the long-term reinforcement effect; Creep and shrinkage of concrete in prestressed scheme will decrease late prestressed beam body;External prestressing scheme needs to strengthen the anchor head performance during operation, the prestress loss and the condition of the anti-corrosion inspection, timely replacement of anticorrosive grease; During the bridge operation should still strengthen the control of traffic load, avoid overload operation of the vehicle, at the same time should strengthen the daily patrol for the bridge work.