Research On The Construction Monitoring And Control & Feasibility Of Synchronous Construction Of Tower And Girder Of Rail-cum-Road Steel Truss Cable-stayed Bridge

A growing number of long-span bridges have adopted the cable-stayed bridge type since the structural system of steel truss cable-stayed bridge is proposed and the construction technology develops to be mature.Therefore,the research on the construction monitoring and control technology of cable-stayed bridge,especially the rail-cum-road steel truss cable-stayed bridge,is of great significance for the development of long-span bridges.Steel truss cable-stayed bridge features its specific main girder and its unique construction monitoring and control when compared with other cable-stayed bridges whose main girders are concrete or steel box shaped.This thesis has studied the approach of construction mornitoring and control for rail-cum-road steel truss cable-stayed bridge by the project of Wuhu Yangtze River Rail-cum-Road Bridge based on existing research.The main research contents are as follows:(1)The main features of rail-cum-road steel truss cable-stayed bridge,as well as the features of its structure and its construction monitoring and control,have been summarized.This thesis has also concluded the development and present situation of cable-stayed bridge in terms of its construction mornitoring and control method,including its control technology,parameter identification,calculation method and feasibility analysis of synchronous construction of tower and girder.(2)The finite element software,MIDAS,is applied to the establishment of the once-bridge model and the phased construction model of Wuhu Yangtze River Rail-cum-Road Bridge.The reasonable state of the construction stage is figured out by combining the forward iteration method and the unstressed state control method.The phased-construction model is compared with the once-bridge model concerning their completion state of the once-bridge model.And the comparison results show that the two methods are in good agreement with each other.According to the displacement and stress of the key construction stages,the variation law of steel truss cable-stayed bridge in construction stage is summarized.(3)Based on the steel truss cable-stayed bridge with portal main tower,this thesis introduces the synchronous construction method of tower and girder of cable-stayed bridge,and focuses on its merits and demerits,and the factors affecting the constructionmonitoring and control.The feasibility of synchronous construction of tower and girder is analyzed.Besides,this thesis has also conducted comparison analysis with the original construction scheme of tower first and girder later,analysis of the influence of synchronous construction on lateral deformation of the portal main tower,quantitative analysis of the unbalanced load during the synchronous construction,and analysis of structural safety check calculation under the condition of one-side lifting work.Specific measures in construction monitoring and control are provided respectively in light of different factors.(4)Wuhu Yangtze River Rail-cum-Road Bridge is taken as an example to illustrate the construction monitoring and control system of rail-cum-road steel truss cable-stayed bridge.The design parameters which are sensitive to the structural response are found out through the analysis of parameter sensitivity of steel truss cable-stayed bridge.Finally,the parameters are identified by the least square method in the typical example of working condition of frame girder-tension stay cable.