Study On Construction Mechanics Behavior Of Stiff Skeleton Concrete Arch Bridge With Prefabricated Box Bottom Floor

The stiff skeleton concrete arch bridge has many advantages in China due to its large spanning capacity and good performance.In the traditional stiff skeleton construction,a stiff truss system is used to erect a stiff skeleton arch,and a concrete skeleton reinforced concrete arch ring is formed around the concrete skeleton surrounding the concrete.During the construction of the outer concrete,especially when installing the arch box floor formwork,the construction is difficult,the risk is high,and the construction period is long,which often becomes a key factor in the construction.To this end,this paper relies on the Guizhou Yutang Bridge under construction as a project to carry out the rigid skeleton concrete arch bridge with arched floor prefabrication-the study of mechanical behavior during construction:(1)Research on modeling and simplification methods of stiff skeleton concrete arch bridge.The life-and-death unit technology is used to simulate the construction process of the arch bridge.The complex problem of the beam element and the plate element is adopted for the stiff skeleton concrete arch bridge.Combined with the force characteristics and filming principle of the stiff skeleton arch,the shear stiffness equivalent and energy mutual Etc.Theorem,the derivation of the equivalent plate thickness calculation formula for the meridian of the stiff skeleton to the pseudo-web is carried out,and verified by an example.(2)Study on the pouring scheme of the wet joint concrete of the floor between the stiff skeleton segments with the prefabricated floor.According to the characteristics of comprehensive construction period,steel tube and concrete stress,the pouring scheme was proposed.The finite element software was used to analyze the skeleton string stress,floor sill stress and skeleton shape of each scheme,and the optimal wet joint placement scheme was determined.According to the special arch hinge structure of Yutang Bridge,the rationality of arch hinge structure,the timing of sealing hinge and the removal order of buckle back cable are analyzed.(3)Study on the perfusion sequence of concrete in a stiff skeleton steel tube.Using the exhaustive algorithm and the principle of symmetry,combined with the simulation results of the finite element software,the optimal sequence of concrete infusion in the stiff skeleton string is proposed.Based on the theory of linear elastic calculation,the stability analysis of the structure of the rigid skeleton installation stage with prefabricated floor is carried out to obtain the linear stability safety factor of each stage.(4)Study on concrete pouring scheme of arched web and roof of stiff skeleton arch bridge with prefabricated floor.According to the stress and line shape of the arch ring during the construction of the arch box web and roof concrete of Yutang Bridge,the concrete box pouring plan of the arch box and the roof is analyzed based on the deflection influence line theory.