Construction Control Of Steel Truss Cable-stayed Bridge

Cable-stayed bridge has a large spanning capacity,thus occuping a main position in the bridges crossing river.And the steel truss girder cable-stayed bridge is more and more favored by bridge designers because it can meet the requirements of transportating both highway and railway lines.In order to ensure cable-stayed bridge structures formed by stages finally reach the ideal designed state,construction control is extremely necessary.Steel truss cable-stayed bridge has its own particularities in construction control due to its specific main girder form.Taking the Jingzhou combined highway and railway bridge as the engineering background,this thesis aims to explore a set of more complete and practical construction control method for steel truss cable-stayed bridge on the basis of previous studies.The main work and conclusions are as follows:(1)Taking the Jingzhou combined highway and railway bridge as an example and using 3DBridge finite element software to model the real bridge,the ideal state of each construction stage of steel truss cable-stayed bridge with couple towers is determined using the non-stress state method.The final state of the bridge constructed in stages is compared with the once completed bridge state,and the two state is coincide.(2)When adjusting the error between the theoretical state and the actual state,the error of design parameters is classified according to the non-stress state quatity,load and structural system.The principle of reducing construction error by controlling the strench of the cable by "the relative pull-out amount" is expained.The main design parameters causing the construction error of the steel truss cable-stayed bridge is chosen as:stiffness of tower,stiffness of cable,weight of girder,stiffness of girder according to the actual construction conditions.Taking a typical case of cable strench and beam erection as an example,error adjustment is carried out reling on the adjustment of cable tension and parameter identification using the improved least squares principle and an ideal effect is got.(3)Taking the Jingzhou combined highway and railway bridge as an example,closure technology of steel truss girder with double inclined rod in closure segment is studied.The closure scheme is determined according to the degree of construction difficulty and the protection ability of the closure members.Adjustment measures andadjustment quantity of each closure step is calculated through the finite element model.Warning scheme is proposed for unfavorable condition in the closure process and the actual closure process of Jingzhou bridge is introduced in the end.The research results of this paper have important theoretical reference value for the construction control of steel truss cable-stayed bridge.