Key Technology Research On Closure Control Of Long-span Steel Truss Cable-stayed Bridge

Steel truss cable-stayed bridge has advantages of strong spanning capacity,good wind resistant performance.The truss beam is spliced by the rod.The transportation condition is low.Steel truss cable-stayed bridge is widely applied in construction project of the area of cable-stayed bridge and railway cable-stayed.The cantilever girder erection technology is adopt in the long span steel truss girder cable-stayed bridge.The construction of mid span main girder closure is the key link of the whole bridge construction.The problems of many closure points,high closure accuracy and great difficulty in regulation and control of the closure construction,which is the key work of construction monitoring.The paper is based on the Bi high-speed Beipanjiang bridge as engineering background.According to the middle span closure construction,the parameter sensitivity analysis of the closure is carried out and The construction process of the steel truss girder cable-stayed bridge is optimized,and the concrete measures to adjust the closure are reasonably determined.The high precision closure of the span steel truss beam is realized.The main contents of this dissertation are as follows:Based on engineering background of High speed Bi Beipanjiang Bridge,a three-dimensional space bridge structure simulation model is built to simulate the span state of the front axle.Sensitivity analysis was carried out on the influence parameters of the closure joint.The results show that the sensitivity of the closure of the two sides of the Yunnan Guizhou Strait is obviously different,and the Guizhou side is more sensitive than the Yunnan side.Based on adjusting the closure of each closure,high precision closure is taken as the target.The closure temporary of locking structure measures long hole + hole,is determined.The difficult problem of closing the X axis and Y axis of the closure girder is solved and the closure problem is realized.Combined with the method of adjusting the closure error,the concrete operation flow of the closure construction is optimized.The influence matrix method is used to solve the coordinated adjustment value of cable force adjustment and temporary weight,and the relation between thrust and thrust of different planning is determined by successive approximation trial method.The influence of closure error adjustment measures on the condition of completed bridge is analyzed.It is pointed out that the temporary weight and cable force adjustment have little influence on the cable force and alignment of the completed bridge.Pushing has certain influence on the alignment and cable force of the completed bridge,Therefore the jacking amount of the forced jacking should be reduced as much as possible during the construction of the closure.