Application On Construction Control Of Stress-free Status Methods For Steel Truss Girder Cable-stayed Bridge

Although the steel truss girder cable-stayed bridge has many advantages, such as largespan, high bearing capacity, strong integral rigidity, convenient factory construction and so on,this kind of bridge has built little in our country with the reasons of cost and technical. Inrecent years, along with vigorous development of the high speed railway construction inChina, this kind of bridge is becoming the preferred form of bridge in high speed railway anddouble road. However, compared with the concrete box and steel box girder cable-stayedbridge construction, the bridge are studied less in the design, construction and control. Thispaper set a steel truss girder cable-stayed bridge as an example, with the help of Stress-freestatus method, hoped to solve the concerned construction control problem, and studied thefollowing points:(1) Calculate the reasonable cable force of the steel truss girder cable-stayed bridge:according to the minimum energy method, using the influence matrix, considering the axialforce and the moment structure, to calculate the cable force which the satisfies the minimumenergy method, and according to the structure deformation limit, adjust the cable force to therational cable force, which meet the final bridge state;(2) The theoretical basis of the stress-free status method: using the theoretical basis ofenergy conservation and energy variational principle, establishing the calculation model ofconstructing bridge and constructed bridge, Through the relationship of the stress anddeformation between the construction process and eventually state, set up the conditions ofthe stress-free status method is that the girder’s unstressed state is Invariant;(3) Calculate the girder’s length on the unstressed state of the steel truss girdercable-stayed bridge: Using the relationship between the construction process and the finalbridge state, analyzing the final state of the steel truss girder bridge, calculate the girder’slength of steel truss girder cable-stayed bridge in unstressed state, and simulating theprocess of construction, get the relationship between the manufacture line and installationline;(4) Determine the tension of the cable to the steel truss girder cable-stayed bridge: thecable force is only adjustable vector in the steel truss girder of cable-stayed bridgeconstruction process, through the construction calculation simulation, get a group cable forcewhich can meet the construction requirements;(5) Adjust the error in the steel truss girder cable-stayed bridge construction process: therandomness of construction cause the error could not be predicted, the steel truss beam isconnected with high-strength bolt, unstressed closure demands litter err to the three closingport, through calculated the cantilever construction error sensitivity, comparing temperature, cable stress adjustment, weight lifting, temporary pier adjustment, obtained a group ofreasonable error adjustment procedure.