چكيده لاتين :
Lift installation of a major marine or offshore structure necessitates detailed evaluation of
inter-dependent engineering and construction constraints that influence the feasibility, safety
and cost-effectiveness of the lifting operations. Due to the advancements in heavy lift
technology, large modularized ship blocks may be fully outfitted, and then lifted and joined
to form the entire ship. Similarly, an offshore structure may be fabricated in a yard,
transported to the selected offshore location, and then installed by lifting. The objectives of
this paper are to find the locations of optimum positions of offshore platform heavy lift
points using the method of evolution strategies either minimizing the moment or
maximizing the natural frequency. The results obtained are compared with the published
results. The optimal positions of simple supports are located to maximize the fundamental
frequency of beam or plate structure taking into account both elastic and rigid supports. The
minimum stiffness of a simple support (or point) that raises a natural frequency of a beam to
its upper limit is investigated for different boundary conditions. The solution also provides
insight into dynamics of a beam with an intermediate support for more general boundary
conditions. Finite element approach is used for solving the problems. The computer
packages such as PRE\V!N/FEAST, SAP90 are used for performing finite element analysis.
