| The formation of a long-span flying-swallow-type concrete-filled steel tubular arch bridge structure is complex and involves many processes.As a self-erecting system,its structure constantly changes during the construction.To study construction monitoring has important effects on the construction safety,the driving comfort level and the durability of the structure.Based on the Hejiang Yangtze River Highway Bridge(main span 507m)under construction,this paper carried out a study on the construction control calculation,control measures and the construction plan optimization of the long-span flying-swallow-type concrete-filled steel tubular arch bridge system.The main work of this paper is as follows:(1)This paper discussed the development history of bridge construction control,and summarized the construction control technologies applied in concrete-filled steel tubular arch bridges.This paper also clarified the construction control thinking of the 500-meter flying-swallow-type concrete-filled steel tubular arch bridge system,and pointed out the content and difficulties in carrying out construction monitoring.(2)The forward analytical method of integral casting with hollow steel tubes + subsequent loading was used to study the internal force and profile under a reasonable bridging state,and to provide control target parameters for the construction control calculation.This paper analyzed the setting rules and distribution methods of the precamber,and discussed the temperature difference effect,the shrinkage and creep of the concrete in the tube,the geometric non-linear effect and other factors that may affect deflection.It also pointed out the effect weight of each factor on bridging profile and discussed the effect rules of fabrication profile deviation on bridging profile.(3)Taking the stress-free state method as the theoretical basis,the calculation of cable force control during arch rib hoisting was studied.It illustrated the calculation with the stress-free state method during arch rib hoisting by taking a simple diagonally drawn buckled structure as an example.It pointed out the cause of the non-unique control profiles during the multi-section arch rib hoisting against the arching targeted profile after taking down the same cables.The optimization algorithm was used to calculate the backstay cable force during hoisting,and two different construction plans of buckled cable tensioning in one trip and cable adjusting during the system conversion period were proposed.By comparing the differences of arching profiles under different cable force courses,this paper pointed out that as a temporary structure,the buckled cable will not affect the profile of the permanent structure after closing and dismantling the cable.Through adjusting the stress-free state parameters,the cause of the finite element calculation error during arch rib hoisting was analyzed.(4)During the construction of flying-swallow-type concrete-filled steel tubular arch bridges,there are processes of tubular tied tensioning by several times and sectional ringed concrete casting in the sidespan.To optimize the construction process,the stress performance of the sidespan and mainspan in the loading process was discussed.An optimization plan for the force and order of tubular tied tensioning was proposed.By taking the tensioning force as the adjusting vector,the influence matrix of the tubular tied tensioning force on the control target during the construction was rationally simplified,to control the tension in a feasible domain under constraints.The optimized tubular tied tensioning plan solved the problem of unbalanced force during the construction of flyingswallow-type arch bridges.The optimized plan allowed the horizontal thrust of the skewback,the bending moment at the bottom of the bearing platform and the tensile stress of sidespan concrete to be controlled within a range that was more conducive to the structure under stress. |
PDF Full Text Request