Optimization Design And Engineering Application Of Flexible Suspension Bridge In Mountain Area

The stiffness of flexible suspension bridge is small,when the live load is passed on the bridge,the geometry of the main cable changes accordingly.The larger the load,the larger the local deflection of the deck.This paper analyzes the optimal design of the flexible suspension bridge from the aspects of controlling the stiffness of the structure and the deformation of the main beam.The simplified calculation method of deformation stress of flexible suspension bridge is studied,and the influence of gravity stiffness of flexible suspension bridge,elastic stiffness of main cable and bending stiffness of stiffened beam on deformation of flexible suspension bridge is studied.The influence of the main structural parameters on the deformation of the structure and the stress of the stiffener beam is studied.The results show that the flexural span ratio of the stiffener beam is mainly determined by the ratio of the constant live load and the vertical span ratio of the main cable under uniformly distributed and concentrated loads.The effective way to reduce the span ratio of the structure is to increase the ratio of the constant live load and to adopt a smaller span ratio of the main cable.Compared with the gravity stiffness of the structure,the stiffness of the stiffening beam is in a secondary position.In the design,the method of welding section steel can be abandoned,and the stiffening beam can be set as hinge in the longitudinal direction,and the stiffening beam can no longer bear the whole bending moment,but as a local stressed member,which can effectively improve the stress of the stiffening beam.In order to improve the mechanical performance of the flexible suspension bridge and control the deformation of the main beam,three measures were adopted,including increasing the restraint at the end of the main beam,adding the central buckle,increasing the restraint at the end of the main beam and adding the central buckle.The results show that the deformation of the main girder decreases greatly when the restraint at the end of the main girder is added and the central buckle is added.The axial force and stress of the structure increase locally,which is within the stress range of the steel beam.The stress of the structure is reasonable,the deformation is small and the durability is improved obviously.The optimal design of flexible suspension bridge can effectively improve its deformation and stress performance,reduce the disease of the bridge,and improve the service performance of the bridge.