Mechanical Behavior Analysis Of Abnormal Shaped Cable-stayed Bridge Pylon

The Pylon anchorage zone plays a vital role in the overall security of stayed-cable bridge. This thesis take Yiyang Bridge as the project backgournd. The tower of this bridge is an unique abnormal shaped one without supreme beam, and its sectional dimensions from top to bottom changes very obviously. Its force analysis and construction are relative complex under the combined action of stayed-cable and circumferential prestressing anchor system, so the pylon anchorage zone is the key part in bridge design. To meet the design needs, this research, based on the global analysis of the full-bridge, applies the finite element software ANSYS to carry out spatial detailed stress analysis. special attention is paid to the research on the tower anchorage zone of prestressed hoop anchoring system. the main work and results of this thesis are as follows:(1) By consulting relevant literatures, the author investigated the form of cable-stayed bridge pylon, and various forms of anchorage zone of cable anchors with their advantages and disadvantages listed, and mastered the characteristics of prestressed anchor system and current research trends;(2) A whole model of Yiyang Bridge was built with utilization of the bridge structure calculation software MIDAS/CIVIL. This research specially focused on the overall shrinkage, creep and temperature on the impact of Yiyang Bridge Pylon,as well as the role of the force and displacement under various load combinations;(3) A comprehensive study of the stress distribution of three-segment model in three different conditions was conducted by selecting the top three segments of Yi Yang Bridge's cable-pylon anchorage zone. Curve graphs are plotted by selecting several nodes regularly. There are obvious stress concentration at stay cable found in the channel, prestressed steel beam anchor point, steel plate and concrete blocks at the junction of the teeth, in both directions at the junction of the column wall and a corner portion tendons channel corner, etc., stress distribution characteristics are consistent with previous studies;(4) The three-segment model was simplified into two-segments based on the stress analysis of three-segment model. By comparing the force conditions of two-segment model in U-shaped transverse, U-shaped vertical and well-shaped prestressing system, this research concludes that the most reasonable layout form are U-shaped transverse;(5) The two-segment model of cable-pylon and the parameters related to prestressed steel were analyzed, the varies of control point stress values in the process of parameter changes were surveyed by selecting the appropriate stress control point, and the most reasonable form of circular prestressing force was concluded; this research solved the problem of excessive centralized local stress and inconsistent prestressed reserve in two-segment model by adding detailed structural measures.Some laws and conclusions were drawn via the analysis of this research, and they are expected serving as the reference for Yi Yang Bridge cable-pylon anchorage zone design.