Research On The Cable-Tower Anchorage Structure Of Long-Span Railway Steel-Truss Cable-Stayed Bridge

Concrete bridge towers are used in most of completed cable-stayed bridges more often. The cable-tower anchorage regions are important mechanical constitution transmitting the local concentrated force of the cable to tower pillar safely and evenly, whose force status is an important issue to consider. To balance the enormous tensile stress in the cable-tower anchorage due to cables, some plane pre-stressing tendons are arranged within the tower walls for the pre-pressure of anchorage areas in order to prevent section cracking and enhance its cross-section bearing potential. There are many ways for the layout of plane pre-stressing tendons, it must be in accordance with the distribution rules of the tensile stress due to cables in anchorage regions in order to make use of pre-stressing effectively and save materials and in the same way,some stages such as pre-stressing construction and operation are need to be considered to make sure that the stress distributions is relatively uniform in the anchorage regions under various loading combinations, taking into account factors such as construction and convenience.In this dissertation a detailed space finite element model for the cable-tower anchorage region based on a large railway steel-truss cable-stayed bridge is builded by a large widely used finite element software ANSYS to examine the stress distribution rules under a variety of adverse loading conditions and comparatively analyze the force performance and differences under the three different layouts of pre-stressing tendons, which is to make sure of the best solution and application. The content of the dissertation is as follows:(1) A summary of the development of cable-stayed bridge and the current status of the use for railways is made with a brief review of previous studies on the situation and the development process for the anchorage zone.(2)The various types and characteristics and application and development trends are summarized aiming at the cable-tower anchorage structure.(3)By a finite element simulation analysis for the cable-tower anchorage regions a detailed study is carried out on the force performance and the stress distribution rules under a variety of loading conditions and its combinations within all kinds of different layouts of pre-stressing tendons. (4) By comparing and analyzing three kinds of programs of layout of the pre-stressing tendon which are curved well-shaped steel bar and U-shaped steel bar transversely opened and U-shaped steel bar longitudinally opened, their advantages and disadvantages are to be pointed out and the best solution is to be chosen according with the actual project situation. In comparison, it's appropriate to prefer to use programs of the curve-well steel bar layout and U-shaped steel bar transversely opened while the value of the cable force is much larger and the compressive reserve in tower wall is enough. So U-shaped steel bar transversely opened can be more favorable because of avoiding many adverse factors and simplifying the construction process than the other two schemes.With the research of the dissertation, we can obtain some valuable rules, which are valuable and can be used for reference in design and construction and bridge monitoring for homothetic anchorage regions.