| Concrete-filled steel tube arch bridge has been developed rapidly in the field of transportation in our country because of its many advantages such as large bearing capacity,large rigidity,good durability,beautiful shape and fast construction speed.However,due to the short application time of this structure form,there are still many deficiencies in the related technical specifications and design theory.With the increase of span diameter,how to ensure the construction accuracy and the safety of the construction process become the primary problem.In order to ensure the normal use of the bridge and the safety of the construction process,it is necessary to study the calculation of reasonable construction cable force and the key working procedures in the construction of the cable-stayed method.In this paper,the Tangjiahe Bridge as the background of the project,focusing on the reasonable calculation and optimization of construction cable force,concrete pouring process of arch rib and construction process of arch construction three aspects,the main research contents and results are as follows:(1)Using Midas/Civil and BRanalysis finite element software,the initial tension of the cable was calculated when the zero bending moment method,the improved zero displacement method and the elastic-rigid support method were adopted.Taking the sum of the square of the cumulative displacement of the control point and the displacement difference of the primary landing frame as the optimization objective,and taking the stress of the arch rib as the constraint condition in the hoisting process,the initial tension was optimized by the built-in optimization function fmincon of Matlab.The influence of the tensionality effect and the temperature effect on the tensioning force is analyzed,and the first kind of stability problem in the process of hoisting is studied.The calculation formula of cable force and the method of solving the stress-free length of the wavy cable with transverse limit of arch rib are deduced,which solves the problem that the initial state of the wavy cable is difficult to be determined in the actual construction.(2)Based on the principle of double element method,conversion section method and unified theory method,the difference of calculation of three methods of arch rib combined section simulation is compared.Taking the stress,displacement and stability of the arch rib in the concrete filling process as the evaluation index,the reasonable filling order of the concrete is studied,and the best scheme is selected and the construction is guided.The mechanical behavior and temperature effect of the recommended perfusion scheme were analyzed,which further verified the rationality of the proposed scheme.(3)Calculate the arch foot bending moment influence line and the arch roof deflection influence line,and according to its characteristics put forward the arch upper building load principle of "successive erecting,symmetrical installation",compared and analyzed the different arch upper building load plan under the arch rib stress state;In view of the instability of the high column in the process of erecting,the method of temporary consolidation with the boundary pier when erecting the T-beam is put forward,which can effectively improve the stability of the high column in the process of construction and has good engineering practicability.(4)The finite element analysis software Midas/FEA was used to establish the detailed model of the joint of the column and the rib,through the application of the column top deflection simulation of the assembly error of the column during the construction process,and then the column and the rib joint stress distribution under the assembly error of the column was studied.The results show that a small amount of deflection occurs at the top of the column,which has little effect on the stress distribution of the fine part at the joint of the column and the rib,does not change the position of the maximum stress.When the same deflection angle occurs,the column is more disadvantageous to the structure force. |
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