Research On Working Platforms And Pouring Length Of Each Section Of Outsourcing Concrete Of Stiff Skeleton Arch Bridge

The construction of the stiff skeleton method had greatly improved the spanning capacity of concrete arch bridges.my country had adopted this method to build many large-span concrete arch bridges.The core issue of the development of stiff skeleton concrete arch bridges was how to use the weaker stiff skeleton to safely form concrete arches ring.In our country,the method of split ring and Multi-working platforms was used to pour the outsourcing concrete to form the main arch ring,which had a better load adjustment effect on the force and deformation of the stiff skeleton.This paper taken the already built Nanpan River Bridge and the Tian’e Longtan Bridge under construction as the engineering background,and discussed the influence of the number of working platforms and the pouring length of each small section of the working face on the force and deformation of the skeleton during the process of outsourcing concrete pouring.Research had been carried out,and the specific contents are as follows:(1)Organized the development status of stiff skeleton concrete arch bridges at home and abroad.Consulted related literature,introduce four load adjustment methods and related examples in the process of pouring outsourcing concrete,compared and analyzed their advantages and disadvantages,and concluded that Multi-working platforms pouring was the main method for outsourcing concrete construction of long-span concrete-filled steel tube stiff skeleton arch bridges.(2)The theoretical basis for dividing the length of each section of the working platform was discussed.The pouring method for Multi-working platforms with split loops was introduced emphatically,and the principle of superposition of stress influence lines was introduced.Taking the concrete tensile stress in the upper chord of the arch foot as the control target,the reasonable length of each section of the working platform was calculated.(3)Taking the Nanpan River Bridge as an example,the rationality and accuracy of the method of dividing the length of each section of the working platform used in this paper was compared and analyzed.A comparative analysis of the force of the stiffness skeleton under different working platforms and different vertical pouring sequences was obtained,and the change law of the stiffness skeleton hand and a better vertical pouring sequence in different working platforms were obtained;The superposition of stress influence lines was introduced.The concrete force in the upper chord of the arch foot was the control target.The pouring length of each section of the working platform was calculated,which solved the tensile stress of the concrete in the upper chord of the arch during the pouring process.The force,deformation and stability of the original plan and actual measured values were compared.Comparative analysis proved the reliability and optimization effect of the model.(4)Study the pouring plan of the outsourcing concrete of Tian’e Longtan Bridge.Using the research experience and summary laws of the Nanpan River Bridge,analyzing the force and deformation laws of the stiffness framework under different working platforms,it was concluded that the six working face scheme was better,and according to the method proposed in this paper,the pouring of each small section of the working platform was obtained.The length ensures that there was no tensile stress in the concrete in the upper chord of the arch foot during the pouring process,and a more reasonable outsourcing concrete pouring plan was recommended.Based on the numerical simulation analysis of the two bridges mentioned above,this paper theoretically studied the change law of the instantaneous stress and permanent stress of the rigid framework under multi-platform casting,and provided an applicable method for determining the pouring length of each small section of the working platform.