Study On Cooperative Force Of Concrete Filled Steel Tube Tied Arch Bridge-cast-in-place Support

As a kind of bridge structure with large stiffness,strong spanning ability and beautiful shape,concrete filled steel tubular tied arch bridge is more and more widely used in highspeed railway,highway and municipal bridge engineering.The construction of concretefilled steel tubular tied arch bridge generally adopts ’ beam first and arch later ’,that is,the concrete tie beam is poured by bracket,the prestress of tie beam is tensioned,and then the steel pipe arch rib is erected and the arch rib concrete is poured.The types of temporary supports mainly include full support represented by disc buckle support and beam-column support represented by bailey beam support.In the traditional design of the support,the weight of the tie beam,the concrete filled steel tube,the formwork and the support,the construction machinery and the personnel load are generally considered,and all the loads are borne by the support.In fact,after the prestressing of the tie beam,the tie beam and the support can work together to bear the load of the arch rib support weight and the concrete filled steel tube weight.The research on the cooperative force of concrete filled steel tube tied arch bridge-temporary support can optimize the existing support design theory,improve the construction scheme and reduce the construction cost.The main contents of this paper are as follows :(1)Using the theory of flexible foundation beam,a collaborative force calculation formula for the beam and truss-type support under concentrated load has been derived,and the calculation expressions for displacement,rotation,moment,and shear force have been obtained.The computational results have been verified using SAP2000 finite element software.The key parameters analysis has been carried out to investigate the impact of calculated formula parameters on collaborative force load allocation.(2)Using the theory of double flexible foundation beam,a collaborative force calculation formula for the beam and trellis-type beam under concentrated load has been derived,and the calculation expressions for displacement,rotation,moment,and shear force have been obtained.The computational results have been verified using SAP2000 finite element software.The key parameters analysis has been carried out to investigate the impact of calculated formula parameters on collaborative force load allocation.(3)Midas / Civil was used to establish the spatial finite element collaborative stress model of the tied arch-disc buckle bracket and the tied arch-beam column bracket,and the stress and deformation of the bracket in each construction stage were analyzed.The load and deformation of the support were analyzed during various construction stages.In addition,the load distribution law of the plate rack and beam column type support were studied after post-construction load actions,providing theoretical support for the design optimization of temporary structures.