Application And Study Of Cable-Stayed Suspension System In Bridge Alteration Work

Along with the development of the time, transportation has improved continuously, bearing value of vehicles has rose, car speed has been raised a lot, the higher requirement was presented for driving safety and comfort. Old bridges has become unsuitable, whether to ultimate bearing ability and adaptability, or to traffic volume. And with the development of time, disease of bridges may occur itself, affect the traffic, reinforcement and transformation of old bridges emerged. Reinforcement, transformation and maintenance engineering is complicated work. Alteration method changes with the old bridge type or address. Society develops continuously, and bridges are built continuously. New bridge will become old ones early or late. So reinforcement and alteration of old bridges will become permanent technique problem. It is one of the important parts and key technologies too.Rapid progress of our country economic construction improved the traffic volume rapidly. Many city bridges has become from "smooth passing work" to traffic bottleneck. To improve passing capacity of existing bridges by widening and alteration work has become a new technique problem. Through a great deal of engineering practice, internal scholars have generalized correlation theory about widening and alteration and accumulated deal of engineering experience. But using cable-stayed suspension system to widen suspension bridges is a new method, and only few people worked on the attempt. It is difficult to find correction design data and theories.Through the study of widening and alteration of Xiaopingdao Shengdao bridge (a ground anchor suspension bridge), using finite element software to do a great deal of calculation, the article will find a practicable and economic widening method, which can not break the original structure. The main jobs are as follows:(1) According to the internal widening work that has finished, collecting data, conclude usual widening method and reinforced technology at present, based on the advantages and disadvantages of each method, decide that using cable-stayed suspension method to bilateral widen bridge is the best one. Add new steel girder under the original concrete beam to improve ultimate capability.(2) To widening alteration of main bridge, using finite element theory to calculate the alteration before and after, by building finite element model. According to the calculation results, improve the original project and study the mechanical properties of the new structure. Evaluate economic performance of each scheme, and attest that the new method is economic and reasonable, fill with the bearing capability and normal use capability, under the most disadvantage loads.(3) To approach bridge and substructure, according to the local condition and structure feature, comparison the usual methods of widening alteration scheme, fully apply reinforcement technology of bar planting, gluing steel plate, altering structure system, adding external tendons and so on.(4) To local members of bridge, such as new dorsal cord anchor, design of saddle and so on. Adopt reasonable calculation method and present detail analysis to assure the design of local member is safe and reasonable.