Scope of supply
- Parallel strand stay cable system
- Internal viscous dampers on all stays
- Pylon anchorage boxes, fabricated in house
- Stressing, adjustment and final geometry
Divisions involved
The problem
A coastal site with a design wind of 55 m/s and a slender deck meant the stays needed damping from the day they were installed, not after commissioning. The pylon anchorage boxes had to be positioned to a 3 mm tolerance inside a slipformed concrete pylon.
What we did
Anchorage boxes were fabricated and trial-assembled at Butibori against the survey model, then set in the pylon on adjustable frames surveyed at every lift. Stays were installed strand by strand with a mono-strand jack from deck level, avoiding any heavy lift at pylon head. Damper sizing was recalculated after the first eight stays using measured deck frequencies rather than modelled ones.
What happened
Final cable forces were inside 3 % of the design values across all 128 stays. Measured stay vibration under monsoon conditions stayed below the fib comfort limit without retrofit.
Measured outcome
- 340 m
- Main span
- 128
- Stays
- 73 strand
- Largest cable
- 116 m
- Pylon height