The Simulation Analysis Of Large Span PC Rigid Frame-Continous Composite Bridge Reinforced By Partial Cable-stayed

With the rapid growth of economy,the increasing traffic brings greater responsibility to the bridge builders,and also puts forward higher requirements for the carrying capacity of bridges which have been built.For some large span bridges that have been put into use,although the structural performance requirements have been met,there are still some diseases that damage the structure.Especially in some large span prestressed concrete rigid frame continuous girder bridges,there are serious secondary side span,middle span lower deflection and box girder oblique cracks,which seriously affect the safety,durability and performance of these bridges.The reinforcement of such bridges has become a hot spot.Based on the research results of bridge disease reinforcement design both at home and abroad,and considered the advantages and disadvantages of traditional reinforcement methods for the Large Span Rigid Frame Continuous Composite Bridge,the application of reinforcement method of Partial Cable-stayed system in practical engineering has been analyzed.Based on the reinforcement of a T structure bridge in Ningxia,the mechanical formulas of two kinds of load modes under static and dynamic loads are proposed,deduced and verified.During the period of operation,serious deflection and web inclined cracks occurred,and the external prestressing reinforcement and Partial Cable-stayed system strengthening were carried out since the special bridge in Shandong,the Yellow River was constructed in 1993.Based on the actual engineering background,the following analysis work is carried out:1.Using MIDAS/CIVIL structural analysis software to establish the discrete model of full bridge structure,and the structure and design parameters of the existing structural bridge are checked.Based on the actual bridge test report,focusing on the prestress losses,stiffness reduction analysis and creep coupling damage parameters,determining the damage parameters based on the time-varying damage model under the effect,in order to simulate the actual state of the original structure before reinforcement.2.Based on the actual state in the correct premise of strengthening structure simulation,the rod model was established,the limit state of external prestressed reinforcement and partially cable-stayed system was checked.The results showed that the reinforcement effect of external prestressing is not obvious,and it can not effectively improve the problem of structural deflection.The method in improving the effect of beam deflection of the mid span of a significant portion of cable-stayed system,the whole process of reinforcement,and the reinforcement of box girder stress on the top and bottom in the standard range,and stress reserve in large,in order to guide the actual reinforcement engineering construction.3.Based on the premise of envelope design principles,the analysis of stiffness parameter of different damage conditions under Partial Cable-stayed system reinforcement was put forward,through the analysis of different stiffness under partial cable-stayed bridge structure design parameters such as height,cable force,different damage parameters of stiffness reinforcement range,which can provide helps for the design of reinforcement parameters part of the cable-stayed system selection.