Study On Optimization Analysis Of Cable Force For Construction Control Of Long-span Multi-arch Bridge

Non-bracket cable-stayed suspension and cable-stayed method is common construction method being used to install Long-span arch bridges. At present, there are much studies about cable force and pre-camber of segment in the process of construction in double-rib arch bridge in domestic, but the calculating method about cable force and pre-camber of segment in the stage of arch installation of multi-ribbed steel truss arch bridge has not been studied yet.Based on the three ribs steel truss arch bridge has being constructed—Daning River Bridge as the project background, is relying on The focus of scientific research projects in Transportation Committee of Chongqing city"the key construction and design technology studies in long-span steel truss arch bridge", and carries out the study on cable force controlled and optimization analysis in the construction of long-span and multi-rib arch bridge ,the main content is:Firstly, based on cable one-off tension method, the optimization method will be used in the pre-camber and cable force Calculation, and propose the idea that we firstly entirely calculate the cable and anchor force and pre-camber, and then calculate the calculate the cable and anchor cable force and pre-camber in sub-segment.Secondly, for the past problem that arch rib of long-span arch bridge in the process of construction control become into the saddle-shaped arch after it is out of the role of cable, this paper introduce the concept of negative pre-camber, and solute the problem of the shape of saddle better.Thirdly, it set the spatial finite element model that make the main arch, tower, cable and anchor cable into integrity, use the zero-order optimization function of ANSYS and APDL language, and draw up the special procedure used for the construction control of multi-ribbed steel truss arch bridge, and this procedure can automatically carry out cable the calculation of cable and anchor force and iteration optimization analysis of pre-camber, with the constraint condition of given expectation linear with the cable losing , allowable value of deviation of tower and one-off tension of cable and so on.Forthly, the special procedure drawn up for construction control is applied in construction control of Daning River bridge. the practice show that the cable optimization method that this paper put out is correct, the theoretic value of cable and anchor cable is good agreement with measured value, the tower deviation of construction control is at 20mm scope, and height deviation and horizontal deviation are 10mm and 5mm at the time of arch closure.Besides, also analysis the affective factor of cable force and elevation in construction.