Study On Constructionsafety Risk Response Of Main Arch Of Extra Large Box-ribbed Arch Bridge

The box arch bridge was widely used in engineering construction,especially across the valley,because of its mature construction technology,unique bridge type,large span and so on.However,the stress characteristics of the arch bridge were relatively different from those of the other bridge types.In the construction process,the stress and strain control were more stringent.Through the research on the safety risk response of the box arch bridge construction,the safety measures of the construction process can be strengthened,Its construction safety and reliability.In this paper,a large mountain box arch bridge as an example to study the main arch ring construction mechanics characteristics and safety response technology.The main contents of this paper were as follows:(1)Analyze the basic theory of risk assessment and risk control,first carry out the overall risk assessment of the arch bridge during the construction period,determine the specific risk assessment content,provide the construction side to provide the basis for construction risk decision;(2)consider the construction risk is mainly reflected in the main(3)Through the design of the safety measures of the arch ribs,the cable winds were designed to evaluate the structural safety of the arch bridge during the construction period,and the main calculation was the stability of the ribs and archs.Cable anchoring design,traffic safety measures designed to carry out risk response design to ensure that the arch bridge during the construction period to achieve safety requirements.Through the above research,the following conclusions were shown:(1)The overall construction risk level of the bridge is Grade IV,which is extremely high risk,and it is necessary to attach great importance to the parties.The construction risk of the main arch ring should be evaluated for structural safety.(2)The stability factors of the upper and lower arches in the installation of cable wind cables and the installation of cable wind cables are 6.11 and 6.05,respectively,which are greater than the specification requirements,ie,meet the requirements of the first type of stability.(3)After setting cable wind cables and adjusting cable forces,the stress condition of arch ribs changes significantly.The position and size of maximum tensile stress and maximum compressive stress in each stage have changed.The values of maximum tensile stress in each stage are less than the resistance of materials.The standard value of tensile strength is 2.65 MPa,and the maximum compressive stress values are all less than the standard value of 32.4 MPa for the compressive strength of materials.The tensile and compressive forces in the construction stage meet the requirements of the code.(4)After the wind cable is installed,the stability of the arch ribs is enhanced;the stress conditions are improved,the maximum tensile stress and the maximum compressive stress are reduced,and the maximum compressive stress and the maximum tensile stress are less than the standard value of the strength of the material.