Civil Engineering Reference
In-Depth Information
deck and over the stay-cable anchorage zone. The load from the deck is transferred
to the towers through inclined concrete struts. The thrust of the struts is carried in
compression by the bottom slab of the deck and by transverse bending in the columns.
Thus there are no portal beams linking the columns.
The twin-leaf layout allows the pylons to adapt to the deck shortening caused
by concrete creep and shrinkage, and by temperature changes. The half decks were
planned to be jacked apart before mid-span closure to preset the columns and reduce
their bending moments. The foundations consist of twenty-six 2 m diameter hand-
dug caissons beneath each column, capped by a 6.5 m deep, 32 m × 28 m cruciform
reinforced concrete pile cap.
Figure 18.21
Ah Kai Sha Bridge: wind tunnel model of towers (Photo: BMT Fluid Mechanics
Ltd)
