Study On Mechanical Property Of The UHPC Arch Bridge

Arch bridge is widely used in engineering due to its great leap ability,high bearing capacity and overall modelling beautiful.However,it is restricted to develop into a larger span by two major factors,namely,the big weight and the construction is hard.The most direct way to reduce the dead load of reinforced concrete arch bridge is to use high-strength and ultra-high-performance concrete.Arch bridge is a kind of compression-flexure member.If UHPC is used to replace ordinary concrete,on the one hand,it can make full use of its high compressive strength,reduce the size of the section,reduce the weight of the arch ring,and at the same time make up for the shortcomings of the arch bridge’s high requirements on the foundation bearing capacity and the substructure.On the other hand,because the material has good durability and corrosion resistance,can extend its service life,reduce the cost of the whole life cycle,has significant economic benefits.At home and abroad,the study of UHPC expansion and application background,this paper presents a set of materials,this paper puts forward the new ideas ultra-high performance concrete arch bridge,It combines the advantages of materials and structures.This paper make some researches and analysis on it,from the engineering quantity of arch ring,rigidity of section,stability and dynamic characteristics o,etc,compared with ordinary concrete arch bridge,proves the feasibility and superiority of UHPC is applied to arch bridge.The specific research contents and results are as follows:(1)Taking the new MiDi bridge in PanZhiHua city as the prototype,the trial design and optimization of UHPC arch bridge were carried out.The spatial calculation model was established by using the finite element software.The results of strength,stiffness and stability checking according to the relevant specifications showed that the UHPC arch bridge was feasible in terms of mechanical performance and met the design requirements.(2)By using UHPC’s ultra-high performance,its section size can be greatly reduced.Compared with the ordinary concrete arch bridge,its dead load can be reduced by 45.65%,and the amount of concrete can be reduced by 49.68%,making it possible for the arch bridge to have a greater span.(3)In addition,the stress of control section is 31% to 70% higher than that of the ordinary concrete arch bridge.However,the strength of UHPC is 3.25 times that of C50.Therefore,the stress 70% higher will not exceed the allowable stress.The axial force of each section decreases.Under the self-respect function,For the axial force,arch springing decreased by 22.07%,the arch roof decreased by 21.92%.For the bending moment,arch springing decreased by 23.29%,and the arch roof decreased by 46.35%.(4)Dynamic characteristics,compares the first ten natural frequencies and corresponding modes,concluded that keeps the same cross section size,the natural frequencies of the UHPC arch bridge is higher than ordinary concrete arch bridge,after the section size decreasing,the natural frequency of vibration of UHPC arch bridge is smaller than normal concrete arch bridge,EI reduce the lower the natural frequency of vibration effects increase with the decrease of the natural vibration frequency is greater than the weight of influence.(5)Try to design the ultimate bearing capacity of the UHPC arch bridge and the related parameters influence are analyzed,draw the following conclusions: geometric nonlinear factors on the little effects on the stability of the arch rib,material nonlinearity is the main factors influencing the ultimate load coefficient in only consider defects within and outside the surface defects,the jump more instability,and across the outside the sensitivity of the flaws in the sensitivity of less than the opposite.(6)The ratio of vector to span has a great influence on the ultimate bearing capacity of arch bridge,along with the decrease of the rise-span ratio,the ultimate load coefficient decreases,The proper selection of span ratio is helpful to improve the ultimate bearing capacity of the structure,The increase of initial defect will reduce the ultimate load coefficient of the structure,but the impact is very small,also should be considered in the design and construction to ensure the safety of the structure.