RMD KWIKFORM designed and supplied the special formwork for the huge 100,000-tonne Gravity Base Structure (GBS) built by Taylor Woodrow at the Barmac dry-dock at Nigg near Invergordon in Scotland. Ii is now in been positioned in the Amerada Hess South Arne field in the Danish sector of the North Sea.

The hollow concrete structure measures 110 metres by 90 metres and comprises 100 interconnecting cells, each 17 metres high. It acts as a massive storage tank, capable of holding 550,000 barrels of crude oil. It also forms the base for topside facilities, which is supported on two legs; one concrete leg centrally mounted and one steel lattice leg attached to the side of the structure.

One of RMD Kwikform's major contributions was to devise an economic and effective formwork solution for soffit support for 96 of the 100, 650mm-thick cell lids. Supporting just the weight of the lid's reinforcement steel and walking load was achieved by spanning three steel beams between the 350mm thick walls of each of the nine metre square cells. These were laid out checkerboard fashion and were used to support permanent RMD KWIKFORM PermaSpan panels, each of which measured approximately 2.15 metres by 600mm or 2.15 metres by 900mm.

To support the load of the 650mm deep lids, RMD KWIKFORM H33 Girders were formed into 9-metre by 4.5-metre assemblies using RMD KWIKFORM Super Slim Soldiers to connect three H33 sections. 21 of these assemblies were constructed at ground level to reduce the work at high level and were then craned into position.

Extended tapered end members on each assembly were located via bearing plates in the cell walls and the soffit formwork below was supported using RMD KWIKFORM Rapid Tie bolts. These bolts were attached to the soffit support steel beams and passed through the steel-reinforced lightweight concrete that was poured onto the multi-ribbed GRP PermaSpan panels. Once the concrete was hardened the Rapid Tie bolts were disconnected and the H33 Girder Tower assemblies were craned to the next section in readiness for the next concrete pour.

In addition to this ingenious lid construction solution, RMD KWIKFORM also supplied its unique Paraslim modular cantilever formwork system for the construction of the structure's 300 metres of roof-level parapet. The Paraslim system is based on a triangular frame supported by a single diagonal tie. This tie is attached to a Paraslim bracket – unique to RMD KWIKFORM – which is fixed to the top of the parapet.

The Paraslim triangular frame itself is based around RMD Kwikform's Super Slim Soldiers as the primary beams, which support conventional RMD KWIKFORM Alform beams. The solution is quick and safe to erect and use.

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