Design And Stress Characteristics Of Loose Cable Saddle Structure Of Large Suspension Bridg

The loose cable saddle is an important component of the suspension bridge,which is used to support the main cable,change the direction of force transmission of the main cable,and disperse the main cable into cable strands and anchor them on the anchorage respectively.The loose saddle is generally a monolithic structure,which is heavy and difficult to transport and hoist.In order to meet the needs of suspension bridge construction in mountainous areas,China adopted a split swing shaft loose cable saddle for the first time in the Kaizhou Lake Special Bridge in Guizhou Province.At present,the research on suspension bridge saddle mainly focuses on the main saddle of the cable,and there are still relatively few research data on the loose saddle and even the split pendulum shaft loose saddle,and the influence of the split structure on the mechanical properties of the loose saddle is not sufficient.Therefore,it is necessary to study the structural design and force characteristics of split pendulum saddle in depth,and the research results can provide a certain reference for the design and selection of loose saddle in the actual project in the future.Based on the single-span steel truss suspension bridge with a span diameter of 1100 m,this paper uses MIDAS Civil to model and calculate the whole bridge to obtain the tensile value of the main cable acting on the loose saddle,and uses CATIA V5 to model the loose cable saddle 3D,import it into ANSYS Workbench,calculate the stress,deformation,stability and dynamic performance of the loose saddle,and study the split pendulum shaft loose saddle.The main work carried out is as follows:(1)The research progress of main cable saddle and loose saddle of suspension bridge at home and abroad is reviewed,and the research status of pendulum shaft loose saddle is introduced.Taking the installation of a bridge pendulum loose saddle as a case,the advantages of split pendulum shaft loose saddle transportation safety and easy hoisting are summarized.(2)The relationship between the vertical bend and the transverse bending design parameters of the loose cable saddle groove is expounded,the theoretical calculation of the split pendulum shaft loose saddle is carried out,and the calculation formula of the shear force at the split of the split pendulum swing saddle and the theoretical analysis of the safety state of the pendulum shaft are supplemented.(3)The suspension bridge relying on the project is calculated,the tensile value of the main cable is obtained and applied to the loose saddle,and the differences in material dosage,stress,deformation,stability and dynamic characteristics of the split pendulum shaft loose saddle and the integral pendulum loose saddle are compared through finite element analysis.The results show that although the material dosage,maximum stress value,deformation,stability and dynamic characteristics of the split type are slightly inferior to the integral type,the local force of the split pendulum shaft loose saddle is more uniform and the material utilization rate is higher.(4)From the perspectives of strength,stability and stiffness,the loose cable saddle was comprehensively studied,and the influencing factors of the force performance of the split pendulum shaft saddle were analyzed,and the bearing capacity coefficient and safety performance of the split pendulum saddle were obtained.Through conservative calculations,it is concluded that the split pendulum loose saddle has a safety reserve of 1.61 times the design load.(5)For the split pendulum loose cable saddle,design the upper saddle head and lower saddle body with different size parameters,use finite element simulation to do force analysis and compare,and study the sensitivity of the split pendulum loose cable saddle to the design parameters of each part Based on this,the structural optimization of the split pendulum loose cable saddle is carried out,and the thickness of the side wall end of the upper saddle body of the split pendulum loose cable saddle is 130 mm,the thickness of the rib plate of the upper saddle body is 60 mm,and the thickness of the lower saddle is 60 mm.The thickness of the saddle steel plate adopts a design combination of 70 mm,which can make the material more efficient.