Experimental Investigation On Design Methods And Mechanical Behavior Of Steel And Composite Bridge Towers

Steel bridge towers have been used for many years in other countries, however, China is still in the primary stage of practicing this type of towers for its own national conditions. With the development of composite structures, composite bridge towers begin to bleed into application. Since the short history of composite structures, the practical engineering and related researches are not enough. With the construction of long span bridges and new types of bridges, steel bridge towers and composite bridge towers will have wide application in bridge engineering. But in China, the guides on the steel bridge towers is not mentioned in the present steel bridge design code, relevant researches are not enough, and the guides can be referred to in foreign codes are also limited, which produces a large difficulty to the design and construction of steel bridge towers. Herein, steel bridge tower's structure design and numerical analysis method are studied and summarized in this dissertation. Through the axial compression full-scale model test and numerical simulation of steel-high performance concrete composite bridge tower, axial compression failure mode and mechanics characteristic are obtained. Moreover, the research results provide reference for the mechanics characteristic study and engineering design of steel bridge towers and composite bridge towers.The main research jobs are shown as the follows:1. The home and abroad development history, application situation and study references are summarized, then, based on steel bridge tower and composite bridge tower's structural characteristic, the main research jobs are put forward.2. Taking test equipment and aims into account, the section model of steel-high performance concrete composite bridge tower with typical structure type are designed, and via to axial compression the ultimate bearing capacity is obtained when the model is destroyed.3. According to the composite bridge tower's change law of deformation and strain, the mechanic characteristic and failure mechanism under axial pressure are extracted.4. Based on the finite element section model, the ultimate bearing capacity is calculated with consideration of material nonlinearity. Then, through comparison of the calculation results and the test results, some suggestions about composite bridge tower's design method are proposed. The results demonstrate that:the bearing capacity of composite bridge tower is higher than the normal steel bridge towers and concrete bridge towers; as for the restriction effect of steel panel to the core concrete, the restriction effect at the four corners is the most strong, at the mean time, the restriction effect at the center of steel panel is the most weak, In order to increase restriction effect of steel panel to the core concrete, a feasible method is setting longitudinal stiffened rib. In order to increase the bearing capacity of composite bridge tower, a feasible method is setting shear connector to enhance the interaction between the steel panel and concrete.5. This paper summarizes home and aboard research results and the project research results, furthermore, bring forward design method for the steel bridge tower, provide reference for the design code of steel bridge tower.