| With rapid constructing of high-speed railway in China, the railway hybrid girder cable-stayed bridge has been widely built to cross large bidies of water, due to its computence for rigidity and mass distribution. The anteroposterior-plate-type steel-concrete composite connection with cells,a critical part for hybrid girder cable-stayed bridge,is widely used to meet the transmission of internal forces and deformation caused by the high speed trains. Due to the complicated structural form and material properties, the mechanical behavior of anteroposterior-plate-type steel-concrete composite connection with cells is still unclear. Especially, both the temperature action and the shrinkage and creep of core concrete have great influence on internal force distribution and deformation between concrete and steel. and consequently, lead to complicate stress distribution and transmission of main beam. Therefore, it is of critical to systematically investigate the complex static behavior of anteroposterior-plate-type steel-concrete composite connection with cells under various load conditions.Currently, there are still few literatures regarding the research on anteroposterior-plate-type steel-concrete composite connection with cells. In addition, the researches on the other types of steel-concrete composite connection mainly focused on the carrying capacity of the special hybrid girder cable-stayed bridges while the stress distribution and transfer mechanism, especially on static behavior under temperature, shrinkage and creep action, have not been studied. Considering the state of art, the author has carried out systematic and comprehensive researches on the static behaviors, i.e. stress distribution, carrying capacity, deformation and transfer mechanism, of anteroposterior-plate-type steel-concrete composite connection with cells of the Yongjiang River Bridge. The research can promote the application of railway hybrid girder cable-stayed bridge, guide the design, construction and maintenance of the steel-concrete composite connection. The main content of the dissertation is as follows.1. Based on the study on existing experimental research on steel-concrete composite connection, the experiment set up of the anteroposterior-plate-type steel-concrete composite connection with cells of the Yongjiang River Bridge, is presented. The design theory, technology route, manufacture, material properties, load scheme and test spot arrangement of test model are discussed. Especially for the design issues of shear connectors in a scale model, the finite element model of the small size of the shear connectors release test was established to calculate carrying capacity and shear stiffness for the comparison between conventional shear connectors and small scale connectors in different aspects, such as shear area, carrying capacity and shear stiffness. the designing method of shear connectors in scale model test was proposed.2. By comparing the results of finite element model and test model, e.g., the stress distribution, carrying capacity, deformation and transfer mechanism of anteroposterior-plate-type steel-concrete composite connection with cells, the correctness of nonlinear finite element model was proved by test model results, which would lay the foundation for further analyses of its static behavior by FEA.3.Based on test model results, the design parameters used to evaluate the state of the axial force transmission and the theoretical model were identified. In addition, the effects of design parameters including the cell length, the bearing-plate thickness, the cell height and the shear stiffness of shear connector to static structural behavior of anteroposterior-plate-type steel-concrete composite connection with cells were analyzed.4. To investigate the static behavior of various types of steel-concrete composite connection under vertical load and horizontal load, the anteroposterior-plate-type, end-plate-type and the front-plate-type steel-concrete composite connection with cells were established usingnonlinear finite element models and the stress distribution, carrying capacity, deformation and transfer mechanism were investigated.5. Based on the concrete shrinkage and creep theories, the concrete constitutive relations considering three-dimensional creep effect has been conducted. The FEA model including the nonlinear material model is implenented in ANSYS with Python scripts, which is used to analyze the influence of the concrete shrinkage and creep of steel-concrete composite segment on the parameters evaluating the state of transmission of the axial force.6. The calculation theories of temperature field and thermal stress have been summarized. According to measured data and meteorological data of the bridge, the temperature model of steel-concrete composite connection has been established and the transient thermal stress has been calculated as well. Meanwhile, its the effects of its load-transmitting performance, deformation and mechanical behavior are calculated under the most unfavorable temperature action. |
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