Research On Construction Scheme Of Steel Box And Steel Truss Composite Beam Of Long Span Cable-stayed Bridge

In recent years,our country’s infrastructure construction is in full swing.At the same time,the bridge construction has been more and more frequent.Because of its beautiful landscape,economic cost and super large span capacity,cable-stayed bridge has been the first choice of many owners and Design Institute.With the increase of bridge’s span,the construction scheme and construction process of cable stayed bridge are becoming more and more important.To ensure the safety and smooth of the construction,it is possible to analyze and study the problems that may be encountered in the process before construction.Nowadays,more and more railway cable stayed bridges are built in our country,among which the steel beam is the most popular one.This article takes the cable-stayed bridge of Dongting Lake as the background project,and makes a detailed study of its main construction process.Dongting Lake bridge adopts steel box and steel truss composite beam,and it is the first time in the world.Therefore,its construction is very difficult and no experience can be used for reference.In order to provide guidance and reference for similar bridge construction in the future,it is necessary to study the key construction technology of the main beam.The main works of this paper are as follows:Firstly,this article has investigated the domestic and foreign literature of cable-stayed bridge,compiled the development history and the construction method of the main beam sof the long span railway cable stayed bridge,and determined the research direction of this paper.And then,according to the actual situation of this project,this article establishes a simulation analysis model with the finite element program,in order to verify the feasibility and rationality of the construction process.Secondly,this article introduces three main girder erection method: "whole segment erection","first steel box girder construction,then the steel truss beam construction" and " steel truss beam construction after five internodes erection of steel box girder construction".Then the author chooses the second method,because of its advantages in bridge deformation,stress state and construction difficulty.At last,the concrete construction scheme of the bridge is introduced in detail.Finally,the author also introduces the main beam’s construction scheme of the bridge.Thirdly,this article deeply studies the construction scheme for steel box girder,and the key technical problems through the analysis of finite element construction stage.In jacking construction,the author analyzes the stress,deformation and the stability of anti-overturning,and put forward the equivalent moment calculation method of the combination of hand calculation and electric calculation.In the cantilever construction,the author focuses on the stress,deformation,the wind resistance stability of the structure,and steel box girder closure scheme.Finally,this article deeply studies the construction scheme of steel truss beam in the method of "first steel box girder construction,then the steel truss beam construction".For unequal longitudinal deformation between the lower chord rod and the upper chord of the steel beam,this article puts forward adjust the length of the bar in the design stage.For the large stiffness of steel box girder member and the difficult of adjustment,the author analyzes the difficulty of the deformation adjustment,and therefore the solving measures are put forward.For installation of top chord is influenced by errors,this article puts forward the “install by group and reserve adjustment port between groups” installation scheme.