Stay cable and suspended
The cable arrangement at tower level has a great influence both on influence on both the aesthetic and economic aspects of the project.
Axial or lateral planes
The Stay cable can be arranged in one or two axial planes or in two lateral planes. The distance between the deck attachments must take into account the deck erection method. The cable size should be limited to allow easier replacement.
Fan and semi-fan system arrangement.
In the fan system, the cables are distributed over the upper part of the pylon. In the harp system, the stay cables are parallel with one another . With the pure fan system, all cables run from the bridge deck to a single point at the top of the tower.
Most cable-stayed bridges use the semi-fan system because of its efficiency and the high level of geometrical freedom that it provides. To extend the practical span range of cable-supported bridges, a combination of suspension and cable-stayed systems could be used
The shape of the tower varies depending on whether the cables lie in one or two planes. An inclined pylon can be stabilised by back-stay cables.
If the stressing anchorages are placed inside the pylon, a minimum clearance of about 3.5 m between facing stressing anchorage bearing plates is recommended.
Cable-stayed structures with saddle designs can be aesthetically attractive. In some bridges, the saddles are designed to allow for cable replacement.
Connection below or above the deck
For concrete decks, the anchorage is generally placed below the deck. A guide pipe goes through the deck. This pipe can also be used to receive a vibration damping system. For steel or composite decks, the anchorage can be placed above the deck.
Pin and fork system
For some steel or composite decks, the stay-cable connection is designed with a pin and fork system. This more expensive design allows the cable to be aligned during installation, but friction forces prevent free rotation of the anchor during the bridge's service life.
In some cases, the stay-cable deck connection has to be protected from potential damage caused by traffic accidents, vandalism and fire. Protection details vary from one project to another
Two planes arrangement on
Harp system arrangement on
Val de Renne Bridge
Fan system on
Bridge Greece, 1988
Back-stay cables on
Saddle design on
Wadi Leban Bridge
Saudi Arabia, 1997
Anchorage below the deck on
River Leven Bridge
Anti-vandalism systems on
John Paull II Bridge