Research On Reinforcement Technology Of Bridge Deck System Of Long Span CFST Arch Bridge

In the deck system of CFST arch bridges built in early China,a suspension bridge system without stiffening longitudinal girder is often used in arch bridges.The bridge deck system is dominated by crossbeams,and the lack of effective longitudinal connection between the beams leads to the smaller stiffness of the whole bridge deck structure system.Once the suspender breaks,the bridge deck structure is likely to collapse.Such as Xiaonanmen Bridge in Yibin,Wuyishan Bridge in Fujian,Nuoguo Bridge in Panzhihua,Peacock River Bridge in Xinjiang,etc.At present,the common reinforcement method for this kind of structure is to install longitudinal stiffening beams under the bridge,so that the simple floating system can be transformed into a grillage system,so as to improve the integrity and stiffness of the bridge deck.Therefore,it is necessary to carry out a detailed study on the setting of large longitudinal beams and the strengthening and transformation technology of bridge deck system.Based on a highway concrete filled steel tube arch bridge with a span of 175m in southwest China,this paper uses Midas Civil,a general finite element software,to analyze the effect of the number,material,cross-section form of large longitudinal beams and the connection between deck and cross-beam on the reinforcement of the whole deck system in the reinforcement and reconstruction of concrete filled steel tube arch bridge deck system.Three strengthening schemes of concrete filled steel tube arch bridge deck system are put forward,and the static and dynamic analysis before and after strengthening is carried out,which provides some theoretical basis and opinions for the strengthening research of concrete filled steel tube arch bridge deck system.The content mainly includes the following points:(1)The origin of concrete filled steel tube arch bridge is introduced,and the classifieation and structure of deck system of this type of bridge are summarized.The characteristics and cases of bridge deck reinforcement methods are summarized.(2)Based on the history and design data of the bridge reinforcement,the main diseases and their causes of the bridge before reinforcement are summarized,and a reasonable evaluation is made,and the corresponding basis is provided for the reinforcement mode of the bridge.(3)the finite element model was established for static analysis of the bridge before reinforcement.Under two working conditions,the internal force and displacement of the arch rib,the displacement of the bridge deck and the force of the suspender cable were calculated respectively.Then the force values calculated under the two working conditions were compared and analyzed to draw an effective conclusion.Dynamic analysis of the bridge before reinforcement:the dynamic performance of the bridge before reinforcement is studied by analyzing its natural vibration characteristics.(4)The influence of cross-section form,quantity,material and connection mode between cross-beam and bridge deck on bridge reinforcement effect is studied,including arch rib internal force,suspender tension,deflection of bridge deck and its stiffness change.(5)Three reinforcement schemes of integral bridge deck system are put forward according to the relying project.At the same time,the local connection structure of longitudinal and transverse beams is discussed,and the optimal reinforcement scheme is obtained.Through static and dynamic analysis of the optimal scheme,the stress and stiffness changes of the main structures before and after reinforcement are compared,and the effect of the reinforcement scheme is finally verified.