ANZAC Bridge - Sydney

Stay cables   The western tower, along with the first three deck segments, were built at the same time and completed in mid 1993. During construction the three deck segments were supported by scaffolding and when tower construction was completed, the first stay cables were installed.

The sub contractor responsible for the cable stays was Austress Freyssinet Pty Ltd.

Wire strand

Wire strand.

 

The stay cables were constructed from multiple wire strands surrounded by a black polyethylene sheath supplied by Vinidex Pty Ltd.
The individual strands, 15.7mm in diameter, consist of seven galvanised steel wires waxed and covered in polyethylene.
The number of strands in each sheath varied - increasing in number from 25 to 74 towards the centre of the bridge.

wire strands within cables

Wire strands within cables.

Stay Cable outer tube

Polyethylene sheath ready for joining.

12m lengths of polyethylene sheath were welded together on the deck and an initial wire strand drawn in.
The sheath and strand were then winched into place and the initial strand fixed into the anchor points and tensioned to its predetermined load. 3.

 
Cable strands and drawing wheel

Cable strands within the polyethylene
sheath and the drawing wheel.

Stay Cable outer tube

Joined length of polyethylene sheath ready for placement.


The remaining strands were then individually drawn into place through the polyethylene sheath from the deck level using a drawing wheel.
After being secured in an adjustable anchorage point in the tower head, the strand was cut to length and fixed at deck level.
A hydraulic jack at the tower top was then used to set the final strand tension to match that of the initial strand. 1.3.8.

 
The drawing wheel

The cable drawing wheel.

Tower anchor points

Tower anchor points.

 
Anchor points - eastern end

Cable stay anchor points - eastern end.

Anchor points under the deck - western end.

Anchor points under the deck - western end.

 
Stay cables are numbered - eastern end

Stay cables are numbered
viewed from the spiral ramp eastern end

Stay cables are numbered - eastern end

 

Antivibration cables

 

Initially the stay cables were subject to serious vibrations. Experimentation using heavy ropes tying the stay cables diagonally back to the deck solved the problem.
The permanent solution replaced the ropes with thin spring loaded stabilising cables between the stay cables and the deck.
The spring failure safety link was later added.

Antivibration cable mounting to deck

 

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