Civil Engineering Reference
In-Depth Information
Chapter 3
Offshore Structure Platform
Design
3.1 INTRODUCTION
Offshore fixed platform design has three main phases, the first of which is
design of the deck that carries the topside facility. The dimensions of the
deck depend on the function of the platform and the facilities that will be
located on it.
The second part is design of the jacket, which depends on the water depth,
the wave and current loads, and the other loads described in
Chapter 2
. The con-
figuration of the jacket structural system is chosen based on the water depth and
the designer
s experience.
The third phase of design is to assess the robustness of the deck and jacket
design for lifting, pullout, transportation, launching and installation.
The three main components of a steel template platform are the topside facil-
ities (decks), the jacket and the piles.
Topside facilities frequently have three decks: a drilling deck, a well head/
production deck and a cellar deck. The decks are supported by a gridwork of
girders, trusses, and columns.
Figures 3.1 and 3.2
show a plan of the main
deck and two elevation views, including the three common levels on every plat-
form (the main deck, cellar deck, spider deck or mezzanine deck in some cases).
The main function of the topside is to carry the load from the facilities and
drilling equipment. The function of the jacket is to surround the piles and to
hold the pile extensions in position all the way from the mud line to the deck
substructure. Moreover, the jacket provides support for boat landings, mooring
bits, barge bumpers, the corrosion protection system and many other platform
components. Examples of jacket drawings are presented in
Figure 3.3
.Plan
views at different levels are presented in
Figure 3.4
for the highest jacket
level, in
Figure 3.5
for the mud-mat level and
Figure 3.6
for the horizontal
frames at different levels.
'
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