Research On The Maintenance And Strengthening For Prestressed Concrete Continuous Rigid Fame Bridge

With the rise on the highway and railway of traffic discharge ^ the raising of vehicle vociety and the growth of wheel load, a higher demand was presented on intensity, rigidity and durability of the existing bridges, and so forth.In our country, most of bridges were built in 1960s or 1970s, which were based on that time traffic discharge and development planning, so design criterion of these bridges were very lower. In addition, it was inevitable to bring about cracks> concrete rupture, steel rust ^ honeycomb and water proof layer failure, because some established bridges were built by poor construction and maintenance during the course of operating period. All above mentioned lead to durability and bearing capacity couldn't gain to design standard. Maintenance and strengthening must be done on these bridges.In this paper, the best reinforcement scheme, which was found by nerve network and genetic algorithm from serval reinforcement schemes, was applied to strengthen a prestressed concrete continuous rigid fame bridge with many quanlity faults, such as excess fall deflection of the main span deck> serious web slop crack existing between main pier abutment and one fourth span, and very poor mud jacking quanlity in the prestressing tendon tubs. To analyze the ascending displacement, normal stress, principal stress before strengthening and after strengthening. The effect of strengthenment was obvious and the reinforcement scheme was successful.By fitting reasonable external prestressing tendons to ensure ultimate bearing capacity of the bridge, to ensure stress reserve of the main beam, to reduce effectively principal tensile stress, to renew line state of bridge structure and gradient. By covering rational CFRP ( Carbon Fibre Reinforced Plastic) to hinder cracks to further extend. Cross slab steering gear was applied to make the external prestressing tendons steer, in order to make the bridge structure stressed state more clear and safe.By maintaining and strengthening, the existing fault bridge strengthened the total intensity and rigidity of the main girder, to large extend. The strengthened bridge could lengthen its service life and made deck line state , ultimate bearingcapacity and durability, and so on, attain to design standard. The reinforcement scheme and method were useful to design large-span three-dimention stress prestressed concrete bridge, cohensiveless prestressed concrete structure, and provided a lot of theoretical criterions for the strengthenment of existing fault bridges.