Mechanical Behavior Research And Design Optimiztion Of Cable-Girder Anchorage Structure Of Long Span Steel Girder Cable-Stayed Bridges

The anchorage is the connection structure between cable and girder, which is the key area of cable-stayed bridges with large span and steel girder. The anchorage is the key research objects and design area because it’s complex design configuration and it is very sensitive for local stress concentration. The details design of the anchorage structure is not covered by the existing codes and lack of specific guidance.Large scale test models are used to verify the design, which is very expensive. This paper aims at four kinds typical anchorage forms, which is currently very popular in long span cable-stayed bridges with steel girder. Anchorage box, gusset plate, pin hinge and the anchor pipe, are studied extensively.In order to give some constructive suggestions for the design of anchorage structure, following main contents are studied:1. State-of-art and shortcoming of the anchorage structure are reviewed, and the design principles of anchorage structure are summarized the. The structure form, stress characteristic, assembly process and other aspects of four kinds of anchorage structure are introduced in detail. Detail comparison among fabrication technology, maintenance and landscape are made. Combined with the specific cable-stayed bridge, gives the detail application of associated anchorage.2. Theory and method of structure model test design are researched. Combined with typical examples of anchorage structures, the selection principles of test prototype, the test load and data collection methodology are summarized.3. Based on the completed cable-stayed bridges and sub-model methodology, the finite element analysis models of four type anchorages are established, and simulation analysis are performed. According to the structural behavior and the characteristic of force flow, the stress distribution, stress concentration and force flow methodology of four type anchorages are studied. The material non-linear and contact nonlinear are also taken into consideration in the finite element models.4. According to mechanical characteristics and control factors of four kinds of anchorage, sensitivity of parameters are analyzed. The design parameters are chosen based on the analysis of sensitivity parameters, then the simplified formula are fitted, which can be used for the guidance of the design.5. The design of anchorages is optimized based on optimum method of influence parameters’ surface. In the optimum method, the dimensions of plate are variables, the total weight of anchorage is the objective function and the maximum stress in anchorage is the variable of controlled state.6. The fatigue load and verification method, which are defined in BS5400, AASHTO LRFD, Eurocode and Chinese road bridge design code, are reviewed and compared.7. The typical gusset plate anchorage of Zhanjiang bay bridge is investigated as a case study. The fatigue life of gusset anchorage is assessed based on the equivalent standard fatigue load model and the BS5400.8. Based on the Linear Elastic Fracture Method (LEFM), the stress intensity factor of cracks is calculated by empirical formula and the finite element method. The fatigue life assessment of gusset plate anchorage of Zhanjiang bay bridge is predicted by fatigue crack propagation law.