Research On Rise-Span Ratio And Beam-Arch Cooperation Mechanism Of Single-Arch Through Continuous Beam-arch Combination Bridge

In the continuous beam-arch combination system,the arch and the beam cooperate with each other to maximize their respective advantages and bear the external load jointly.The continuous beam-arch combination system is one of the preferred bridge types for urban landscape construction because it has diverse forms and is more in line with the city appearance.This paper is based on a single-arch through continuous beam-arch combination bridge in Xining as the engineering background,combining with mechanical analysis and finite element modeling as the main line.The following researches are carried out on the beam-arch cooperation mechanism and structural parameters:(1)Based on the assumption of equal suspender force and filmy force,the method of structural mechanics is used to deduce the expression of the beam bending moment,beam deflection,arch bending moment and arch deflection under dead load and live load.The formula,as well as the expressions of the load sharing ratio of arch,the bending moment ratio of arch-beam and the deformation ratio of arch-beam,reveal the mechanism of beam-arch collaboration bridge.(2)The quartic parabolic curve is used to fit the suspender force.The error analysis of the formula and the finite element calculation result are carried out to determine the suspender force correction coefficient,so as to reduce the error caused by the assumption of equal suspender force.In the similar way,the cosine curve is used to fit the suspender force.The error analysis of the suspender force formula and the filmy force formula calculation results are determined from the filmy force correction coefficient,so as to reduce the error caused by the assumption of filmy force.Through the suspender force correction coefficient and the filmy force correction coefficient,the correction coefficients of the beam deflection,arch deflection and the proportion of external load sharing by the suspender force are finally calculated to be 1.1,1.2,and 0.9 respectively,in order to reduce the formula error.(3)According to the expressions of load sharing ratio of arch,bending moment ratio of arch-beam,and deformation ratio of arch-beam,combined with engineering background,the author draws the influence curves of each parameter(Suspender-arch ratio of equivalent flexural rigidity,Ratio of beam-arch sectional flexural rigidity,Rise-span ratio,Influence coefficient of axial deformation,Side-to main-span ratio,Side-to main-span flexural rigidity ratio)and load sharing ratio of arch,bending moment ratio of arch-beam,deformation ratio of arch-beam.The influence of structural parameters on the load sharing ratio of arch,bending moment ratio of arch-beam,and deformation ratio of arch-beam is also analyzed.(4)Based on the finite element calculation results,the influence of different rise-span ratio on the single-arch through continuous beam-arch combination bridge is analyzed.The relationship between the internal force of the beam,the internal force of the arch,the suspender force and rise-span ratio is also explored.