Stable Bearing Capacity Study Of Ultra-high Performance Concrete Box Arch Bridge

Ultra-High Performance Concrete(UHPC)has excellent mechanical and permeability properties and is accepted as the most innovative cement materials recognized for nearly 30 years.The arch bridge is a structure mainly bearing the compressure.Applying UHPC to the arch bridge can give full play to the ultra-high compressive strength of this material.There are many advantages in UHPC box arch bridge,such as reducing the size of the section and the deadweight of bridge,improving span ability,shortening period,improving bridge durability and extending service life.The material properties of UHPC between normal concrete and steel,the thinner and lighter UHPC arch ring is more prone to local buckling than normal concrete members under strong pressure.Not only the strength of the UHPC box arch must be considered,but also the stable behavior of the thin-walled members.When calculating the bearing capacity of the UHPC box arch,it is necessary to consider the influence of the overall stability and local stability.This article starts from the actual characteristics of the arch,focusing on the mechanical behavior of UHPC members and structures,the compressive failure characteristics of UHPC box thin-walled members and the stable bearing capacity of UHPC box arch structures.The main contents and results of research are as follows:(1)The preparation mechanism of UHPC was analyzed,and the mechanical parameters such as compressive strength,flexural strength,and elastic modulus of UHPC used in subsequent tests were mastered,which provided the material foundation for later experimental research and finite element simulation analysis.(2)The axial compressive tests on the UHPC box thin-wall columns was conducted,and the failure modes,local buckling characteristics,load-deformation relationships,and ultimate load-bearing capacities were analyzed.At the same time,ABAQUS model was used to compare and verify.Based on the test results and the empirical formula of the bearing capacity for steel box members,the calculation formula of the bearing capacity for UHPC box thin-walled members considering the local stability was proposed.(3)Based on the calculation formula of the stable bearing capacity for steel members and the material characters of UHPC,a formula for calculating the bearing capacity of UHPC box arches based on the equivalent beam-column method was proposed,which fully considered the influence of local stability.The single-point loading test on one UHPC box arch was conducted,and the crack distribution,load-deformation relationships and failure modes were analyzed.ABAQUS model was used to compare and analyze,which considered the material and geometric dual nonlinearity,and gained results in good agreement.Compared with the results of finite element analysis,the measured bearing capacity in the test was closer to the proposed formula.It shows that this formula has good applicability.The research results of this article can provide a positive reference for the subsequent research on design theory of UHPC box arch bridge.