Stress Analysis Of The Prestressed Cable-pylon Anchorage Zones Of An Arch-tower Cable-stayed Bridge

The cable-stayed bridge, which is a composite architecture, consists of the cable-pylon, main girder and cable. Its floor system is compressed and supporting system is in tension. Cable-stayed bridge is applied to the modern bridge engineering more and more for its good mechanical behavior, large span capacity, novel structure, good seismic behavior and ripe construction technology day and day. The anchoring systems of cable-pylon anchorage are the significant points of a cable-stayed bridge, whose main composition is making correspondence position's cable force transferring to the pylon safely and uniformly. Because of the force and structure condition at cable-pylon anchorage segment are complicated, analysis of strength performance of these positions have been paid high attention in the bridge engineering all the time, while anchorage zone of pylon is also the difficult and important part in designing and constructing of cable-stayed bridge.The anchorage system in cable-pylon anchorage zones is infinite branch variety,such as ring pre-stress, square-formed finish rolled threaded reinforcing bar , anchoring steel beam , steel anchor box, etc. Prestressed anchorage has advantages of simple anchoring method, less amount of steel and cheap in price; anchoring steel beam has complex structure, and whose steel consumption is bigger leading to high cost, but it has the features of stressing definite, clear force transferring and guaranteed mechanical performance; steel anchor box's characteristics lie between the other two, which is suitable for cable-stayed bridge with cable in plant layout. In practical engineering design, the selection of reasonable anchoring method is according to engineering budget, capacity of construction and maintenance, and so on. The cable-pylon is compression-bending member which mainly in compression, bringing concrete material into full play of the strong compression resistance capacity, and concrete material's maintenance cost is low. So the cable-pylon tends to apply concrete material, and most of cable-stayed bridges use concrete material in our country, whose anchoring method is mostly prestressed anchorage.Based on the under constructed right branch main bridge of Ma Anshan changjiang river bridge, the theory and simulation analysis of three cable-pylon anchorage zones where concentrated forces of cables are bigger on the top of pylon were carried out in detail. With finite element analysis software-ANSYS, spatial analysis model of cable-pylon anchorage zones is established in this paper; research on their respective functions and interaction of finish rolled threaded reinforcing bars and cables under different conditions is carried out; the mechanical behavior of pre-stressed cable-pylon anchorage zones is summarized and reasonable arrangement of pre-stressed steel within the cable-pylon anchorage zones is also analyzed; attenuation of stress induced by cable tension or pre-stressed along the pylon height is studied on, the conclusion will provide evidence for reasonable arrangement and optimal layout of pre-stressed steel; general design method of the cable-pylon anchorage zones is concluded, then it analyzes and compares the design method of the cable-pylon anchorage zones in countries standard.