Offshore Structure Platform Design - Offshore Structures: Design, Construction and Maintenance - page 101

3.2 PRELIMINARY DIMENSIONS
Topside structures are designed based on requirements of the American Institute
of Steel Construction (AISC), with Allowable Stress Design (ASD) or Load
Resistance Factor Design (LRFD) specifications according to the project require-
ment. The main supporting element is the plate girder or tubular truss, and in most
cases a tubular member is preferred because it incurs little wind load.
The floor is covered with steel plates, usually about 38 mm (1½ inches)
thick. The thickness of the deck framing depends on the spacing between
floor beams and the anticipated load on the deck.
Figure 3.7 is a platform elevation view showing the main parts of the
offshore platform and affected load.

3.2.1 Approximate Dimensions

Large forces result when waves strike a platform ' s deck and equipment. ●

Therefore, the air gap should be at least 1.5 m (5 ft) added to the wave crest
height from the omnidirectional guideline for the maximum wave height for
the 100-year return period, as shown in Figure 3.7 .

●

Control
room

C.G wind
load e ffect

Generator

Gap ≥ 1.5 m

Boat
landing

Max
wave
height

M. W.L

1

10

FIGURE 3.7 Platform elevation view.