Analysis Of Influence Of Parameters On Static And Stability Characteristics Of Half-through Spatial Y-shaped Steel Box Arch Bridge

With the rapid progress of science and technology in China in the past 40 years,steel box arch bridges,steel truss arch bridges and other forms of steel arch bridges have developed rapidly in China,while half-through spatial Y-shaped steel box arch bridges are a new form of steel box arch bridges,there are few studies on the mechanical properties of such bridges at home and abroad.Therefore,it is of great engineering significance to analyze the static and stability characteristics of such arch bridges.In this paper,a half-through spatial Y-shaped steel box arch bridge with a main span of220 m is used as the research background.First,the overall stress of the steel box arch bridge is analyzed.The orthogonal test method is used to sensitively analyze 7 structural parameters Performance analysis to determine the main influencing parameters of the static characteristics of the structure;then,the single-factor parameter analysis is performed on the main influencing parameters of the static characteristics of the structure to obtain the changing law of the static characteristics of the structure at each parameter level;finally,the structural elasticity Stability was analyzed and parameter studies were conducted.Research indicates:(1)The maximum value of arch rib stress under constant load is mainly concentrated between the side arch foot and L/4 ～ 3L/8 of single arch.The main beam and main arch show W-shaped deformation trend under live load.The rise-span ratio and boundary constrained structure are most affected by the force,followed by the arch rib stiffness.The stiffness of the main beam has a certain influence on the static characteristics of the main beam.The characteristics of the hanger have a great influence on the stress of the hanger.The effects of auxiliary arch stiffness and arch axis coefficient on the static characteristics of the structure are relatively small.(2)Under the effect of temperature,the two arch-beam consolidation systems produce large internal forces and arch foot reaction forces.Under the two-hinge arch-beam-articulatedsystem and two arch-beam free systems,the main beam is under poor stress and large deformation.In a hinge-less system,the internal connection stiffness has little effect on stability.The hinge-less arch-beam-articulated system is the optimal structural system form.(3)With the decrease of the rise-span ratio,the internal force of the arch ribs showed an overall rapid growth trend.Different rise-span ratios have a greater influence on the main beam stress and S29 hanger stress.The maximum deflection of the main beam under live load increases first and then decreases,but the change range is very small.Under different load cases,the structural stability has a different trend in different rise-span ratios.This type of bridge should not choose a smaller rise-span ratio.(4)As the stiffness of the arch rib decreases,the internal force and stress of each section of the arch rib show a decreasing trend,and the decreasing trend gradually accelerates.The maximum deflection of the main beam live load is greatly increased,and the increase speed is accelerated.The overall stability of the structure is greatly affected by the external stiffness of the arch rib.(5)As the stiffness of the main beam decreases,the maximum bending moment and stress of the main beam under constant live load are greatly reduced.Under live load,the maximum deflection has a large increase.Due to the reduction of the calculated area of the stress of the hanger or the breakage of the hanger,the stress of the hanger has increased by more than 30%.During operation,anti-corrosion treatment should be carried out on the hanger.When replacing hangers,attention should be paid to changes in the stress of adjacent hangers.The use of wind bracing can effectively improve the overall stability of the structure,but the stiffness of the wind bracing has little effect on the vertical stability.