Study On Methods For Increasing Webs Reinforcement Of Long Span Continuous Rigid Frame Bridges

Due to its unique structural characteristics and construction advantages,the large-span continuous rigid frame bridge has been favored by many bridge builders in recent years and its one of the most extensive bridge types.However,due to various reasons such as imperfect design,unreasonable construction,inadequate maintenance,etc.,a variety of operational diseases will appear after the bridge has been completed for a certain period of time,such as continuous downward flexing across the bridge and cracks in the floor webs,etc.,There are many factors that affect each other and cause a vicious circle.Various diseases have already limited the continuous development of the bridge to a certain extent,and have brought severe tests to many bridge builders.Since the latter half of the last century,a large number of scholars at home and abroad have invested in the study of the bridge reinforcement method.They proposed the paste reinforcement method,the reinforcement section reinforcement method,and the external prestress reinforcement method to provide reinforcement for future generations for valuable practical experience and theoretical support.The main research contents of this article are as follows:(1)Review the relevant literature at home and abroad,summarize the damage mechanism and corresponding reinforcement methods for large-span continuous rigid-frame bridges,and focus on the causes of crossbeam mid-span deflection of box girders and the causes,locations,and bearing capacity of various cracks.and it was found that the preload reinforcement methods are mainly used for external prestress reinforcement methods,and the treatment of cracks is similar to other bridge types.(2)Combine this research topic,based on the traditional external prestressed reinforcement method,the advantages and disadvantages of the method are analyzed,and a reinforcement method for increasing the mid-web and applying prestress in the mid-web is proposed.Effectively improve the related shortcomings of traditional external prestressed reinforcement methods,such as large prestress loss,difficult maintenance of post-prestressed steel reinforcements,prone to secondary stress,etc.,and at the same time have a good reinforcement effect on the bending resistance and shear resistance of the bridge.(3)Taking a certain bridge in Yunnan as the research object,the finite element software was used to establish the traditional external prestressed reinforcement method and the reinforcement method of the mid-web reinforcement method for the operational diseases of the bridge.Based on the calculation results,the control of the two reinforcement models was calculated that including sectional bending moment,shear force,stress and other parameters,analysis and comparison of the reinforcement effect of the two methods of reinforcement of the bridge,and proved the feasibility of the reinforcement method of the middle web.(4)Based on the theoretical feasibility of the reinforcement method of the middle web reinforcement method,through the results of many model calculations,the influence of the web size and layout on the reinforcement effect was analyzed,and it was found that the web thickness was increased without increasing the web thickness.Thickness is inversely proportional to the load-bearing amplitude.If the thickness of the web is increased and the steel beam is increased accordingly,the high-thickness ratio is within a certain range,and the reinforcement effect is relatively good.In addition,through the modeling and analysis of the web layout,an increase in the number of single sheets is found.The reinforcement effect of the web is stronger than that of the double middle web,and it is hoped that it will provide reference for similar reinforcement projects.