| The span of domestic suspension bridges is getting larger and larger,and the size and weight of the main cable saddle have also increased significantly.In view of the limitations of the main cable saddle that cannot be replaced during useful life and the high requirements for safety,the design of the previous main cable saddle was extremely conservative,which contradicted the economics of structural design.Therefore,it has important economic benefits and engineering design reference value to explore the ultimate bearing capacity of the main cable saddle,study the force transmission path of the structure,and optimize the structural design size.The thesis mainly focuses on the above problems,taking the main cable saddle of Longtan Bridge as the engineering background,and adopts the method of numerical simulation analysis to conduct a systematic analysis and research.The main contents,methods and results are as follows:(1)Through the statistical analysis of the structural design dimensions of the main cable saddle of the existing long-span suspension bridges,the structural parameter of the main cable saddle is summarized with a certain regularity,and the parametric geometric model is established based on Autodesk Inventor,which can provide reference for the structural designers of the cable saddle when formulating the design parameters of the cable saddle;(2)For the main cable saddle of Longtan Bridge,the finite element numerical simulation models are carried out based on the ABAQUS.The mechanical properties of the main cable saddle are systematically studied,its force transmission path,failure mode and ultimate bearing capacity are revealed,and the safety and reliability of the main cable saddle of Longtan Bridge is verified.;(3)Establish the parameterized geometric model based on Autodesk Inventor,import the geometric model into the ABAQUS to establish the finite element models,systematically analyze the influence of the main cable saddle design parameters on the bearing capacity,and explore the influence of the material types and geometric parameters on the structural bearing capacity.Based on the influence of design parameters on the bearing capacity,the preliminary design dimensions of the main cable saddle of Longtan Bridge is optimized for structural dimensions;(4)Based on the force transmission mode of the saddle and the destructive nature of the plastic development of each component in the ideal elastoplastic analysis,a method for structural optimization with the safety factor as the goal is proposed,and the preliminary design dimensions of the main saddle of the Longtan Bridge are were optimized for structural dimensions;(5)The multi-linear elastoplastic material constitutive model is used to further explore the bearing capacity of the main cable saddle of the Longtan Bridge after structural optimization,and a preliminary discussion on the evaluation criteria of the bearing capacity of the structure when considering the plastic strengthening of the material.The standard of horizontal deformation,the standard of vertical deformation and the evaluation standard based on the bearing capacity of the main cable can provide a reference for designers to carry out calculation and analysis;(6)Based on the probability theory and finite element numerical simulation technology,the PYTHON material random simulation program is compiled on the ABAQUS,the random finite element models considering the inhomogeneity of the cast steel material are established,and the influence of the inhomogeneity of the cast steel material on the ultimate bearing capacity of the cable saddle is analyzed.The results show that under the static load,the influence of the inhomogeneity of the cast steel material on the ultimate bearing capacity of the cable saddle is negligible. |
