Civil Engineering Reference
In-Depth Information
diameters of 66 mm internal, 72 mm external, and three cables of 19 No 12.9 mm
strands in ducts with diameters of 81 mm internal, 87 mm external, Figure 5.12. The
cast-in-situ reinforced concrete top slab was 200 mm thick.
The limited number of beams did not justify a highly mechanised site. Eight soffi t
forms were laid out, in line with the bridge, Figure 10.14. The steel shutter, equipped
with external vibrators, could be moved from soffi t to soffi t. Consequently it was
possible to work on several beams at the same time, preparing the steel cage, casting the
concrete, leaving the beams in place to gain strength, and then tensioning the tendons.
The beams were then picked up directly by the launcher which was improvised from
Bailey bridge sections, and placed in position. The slabs between the precast beams
were then cast using timber shuttering, suspended from the top slabs of the precast
beams.
10.3.8 GSZ Superhighway, Pearl River Delta Viaducts, Guandong
Province, China
The Pearl River Delta Viaducts extended for 17 km of which over 14 km used precast
Tee beams. The viaducts were built by Slipform Engineering Ltd, the contracting arm
of Hopewell Holdings [3]. Benaim were engaged to design the decks and foundations
by Tileman (S.E.) Ltd, a subsidiary of Slipform Engineering.
The Superhighway consisted of two adjacent carriageways, each carrying three lanes
of traffi c plus hard shoulders. The 15.4 m wide decks required fi ve beams, at 3.45 m
centres, Figure 10.16. The spans were mainly 32.5 m, although there were many
special cases, principally adjacent to interchanges; the precast beams were 2.3 m deep,
included a top slab 1.6 m wide, and weighed 75 tons. The cast-in-situ deck slab and
the webs were 200 mm thick, Figure 10.17. Each 32.5 m long beam was prestressed
by fi ve tendons consisting of 6 No strands of 15.7 mm, in ducts with diameters of
61 mm internal, 71 mm external. The side cover to the webs was 35 mm; the links
Figure 10.16
GSZ Superhighway, Pearl River Delta Viaducts (Photo: Engineer Leo K.K. Leung,
Executive Director of Hopewell Highway Infrastructure Ltd (Hong Kong Stock
Code: 737))
