Cable Force Optimization Research In Reinforced Concrete Arch Bridge Cantilever Cast-in-place Construction Process And Determination Of Reasonable Finished State

In the stayed and cast-in-place cantilever construction of reinforced concrete archbridge,stayed-buckle cable force directly not only affects the structure internal forceand line shape during cantilever stages,but also affects the finished bridge state.Therefore, it is very necessary for reinforced concrete arch bridge based on the stayedand cast-in-place cantilever construction method to calculate stayed-buckle cable force.Based on the background of the under-construction Mu Peng Super Large Bridge ,some study has been done as following:1. It is studied how many methods are always used for cable force calculation ofreinforced concrete arch bridge based on the stayed and cast-in-place cantileverconstruction method at present. By exploring the features of these methods, theadvantages and disadvantages and application range of each method are analysedTaken optimization theory into calculation,reasonable bucking force determinationmethods of large span stayed and cast-in-place cantilever reinforced concrete archbridge based on optimization theory are put forward;2. Combined with the background of Mu Peng Super Large bridge,and accordingto the thought that most of buckle cables use a single tension method and the small usea single two-step tension method in the cast-in-place cantilever construction,theoptimization program is wrote by using APDL language in ANSYS.The space finiteelement model is established . First order optimization method is used for the cableforce optimization in cantilever cast-in-place stage .The optimization results show：theinternal force of arch ring and cable force in stayed and cast-in-place cantilever stagemeet the safe construction requirements,and section integral tension stress is reducedeffectively;3. By borrowing the thought of the minimum bending energy method ofcable-stayed bridge,and according to the stayed and cast-in-place cantileverconstruction characteristics of reinforced concrete arch bridge, the multi-objectivemulti-constraint optimization method is proposed. The mehtod is based on thereasonable finished dead state of cast-in-place cantilever reinforced concrete archbridge. Taken the arch ring moment of each control section after arching for n years asobjective function, the adjustment quantity of stayed-buckle cable force before theclosure of arch ring is considered as the design variables,and the tensile stress of thearch ring control section during the cable force adjustment is considered the constraint condition which can not exceed the permissible value. By using the evaluationfunction method,multi-objective function problem is converted into single objectivemulti-constraint problem,and then single objective optimization problem is solved byusing the extended lagrange multipliers and the BFGS variable metric method;4.By parameter sensitivity analysis of the mechanical behavior in the stayedcast-in-place cantilever construction process of reinforced concrete arch bridge,theimpact on arch segment displacement and section stress is obtained. And the law isobtained that the influence of self-respect error and stay-cables tension error on thearch segment displacement and section stress is greater, while the influence ofstiffness error and cable-stayed stiffness error is smaller;5. It is studied how the demolition order of cables after the arch ring closure oflarge span cable-stayed cantilever casting construction process of reinforced concretearch bridge. By analyzing the effects on segment displacements and section stress ofarch ring under two different orders of cables, one conclusion that it is morereasonable for the demolition order from the vault than from the skewback is obtained.