Research On Structural Performance Of Long-span Continuous Girder-arch Composite Bridge After Vehicle Impact Suspension Damage

In recent years,with the continuous improvement of China's economic strength and continuous improvement of overall national strength,and the bridge business has developed rapidly.The continuous beam-arch composite bridge combines the bending of a beam bridge with the compression of an arch bridge.Advantages,solve the problem of building bridges on soft soil foundation,at the same time also give full play to the material properties and reasonable structural force of the bridge structure,beautiful shape,widely used throughout the country.However,on the one hand,due to the long-term load of the bridge structure,the damage or functional degradation of the bridge boom has a great impact on the life of the bridge;on the other hand,economic development,the increase of vehicles,the impact of vehicles hitting the bridge and the damage to the bridge boom and Fracture will cause the redistribution of the internal force of the boom and changes in the axial force and displacement,which will greatly reduce the service life of the bridge and bring huge economic losses.Therefore,when designing a continuous beam-arch composite bridge,analyze the vehicle impact It is necessary to cause damage to the bridge hanger under the action.This article takes the main span 150 m down-through continuous beam-arch composite bridge as the research object,and studies the related structural response of the long-span continuous beam-arch composite bridge after the vehicle hits the boom damage.This article first collected the domestic and foreign literature on beam-arch composite bridges in detail,carefully read and organize,introduced the development overview of continuous beam-arch composite bridges,summarized the advantages and disadvantages of continuous beam-arch composite bridges,and described the current domestic and foreign bridges in detail.Existing problems and the research status of beam-arch composite bridges are put forward,and the problems existing in the practical application of beam-arch composite bridges are put forward.Finally,the research content of this thesis is explained.Then,the finite element software midas/civil2019 was used to establish a calculation model.Then analyze the response of the single group of suspenders,the damage of the side suspenders when the single group of suspenders break 30%,and the response to the axial force,displacement and internal force of the suspenders when the single group of suspenders break.The force value of the boom will suddenly increase,with a maximum increase of 42.1%.The farther away the broken boom is,the lower the force value of the boom will decrease.From the perspective of the change in displacement,the displacement at the upper end of the boom break will decrease the most,and the boom will break.From the end to the mid-span,the reduction in the displacement of the upper end of the boom at the fracture increased from 5.4mm to 8.0mm.The farther the distance from the fracture boom,the smaller the impact.The influence of the internal force of the bridge structure is not very obvious.When a single group of booms breaks,when the side boom is damaged by 30% or 50%,as the degree of damage increases,the value of the damaged boom force will decrease,and the axial force will increase significantly.The increase of the axial force is close to the degree of damage of the damaged boom.You can also use this rule to determine whether the side boom is damaged and the degree of damage after the boom is broken.From the perspective of displacement,when the boom is damaged,the same side is damaged.The displacement of the upper end of the boom is significantly increased.Compared with a single boom,the displacement is multiplied after the fracture.As the degree of damage increases,the change in the deflection of the corresponding node of the broken boom increases linearly.From the change of internal force,when F1 breaks and F2 damages At 50%,it has a significant effect on the internal force of the bridge structure.The left bending moment and shear force at the foot of F arch both increase multiples,the bending moment of the main beam increases significantly,and the overall change is greater than the impact of a single suspension rod fracture on the bridge structure.Finally,the influence of the two groups of booms on the axial force,displacement,and internal force of the boom at the same time in the typical section is analyzed.The analysis results show that when the two groups of booms break at the same time,the axial force of the adjacent boom suddenly increases,up to 85.2%.The axial force of the boom is very close to the limit of the axial force of the boom.Under long-term vehicle-mounted coupling shock,fracture may occur and cause continuous fracture of the boom,resulting in bridge accidents.From the perspective of displacement changes,when the two groups After the booms break at the same time,the displacement of the upper end of the boom on the same side increases by up to 12.2mm.It can be found that the simultaneous increase of the two groups of booms on the axial force and displacement of adjacent booms is not equal to the linear superposition of a single boom From the change of internal force,the influence of the two groups of suspension bars on the bending moment and shear force of the remaining structure is obvious.Among them,when the two sets of suspenders at the ends break simultaneously,the impact on the remaining structure's internal force is the most obvious.The moment increased by 1.7 times,and the bending moment at 1/4 of the F arch ribs decreased by 3.3 times.The displacement and bending moment of the side beams increased first and then decreased.The maximum increase of the bending moment was close to 7000 kN·m,and the maximum displacement was5 mm.obvious.Figure [78];table [36];reference [54]...