ULTIMATE STRENGTH ANALYSIS OF STEEL JACKET PLATFORM

Currently, there are about more than 80% of offshore platform around
Malaysia's block field aged 30-40years which beyond the original design life of 25
years. With the several numbers of the platform services beyond the original design life,
structural assessments need to conduct the gauge platform performance throughout for
the extended years. There was 2 common method widely used, simplified ultimate
strength analysis and static pushover analysis. Simplified ultimate strength defined as
when any of member, joint, pile steel strength and pile soil bearing capacity reaches its
ultimate capacity. That result the overview of the platform ultimate strength. Static
pushover analysis generally concentrates on RSR (Reserve Strength Ratio) and REF
(Reserve Resistance Factor) for the ultimate strength. The report summarizes two parts
of analysis, first the study of ultimate strength of different leg jacket platform and the
second part is the bracing configuration study. The analyses were a non-linear
analysis where the load will distribute to an alternative of the steel framework until the
structure collapse under allocated condition. It is found that a platform with more legs
has higher ultimate strength compared to less number of legs. Hence a bigger jacket
platform with eight legs has much stiffen than smaller platform and mostly installed at
rough area. Another part of analysis of bracing configuration study where X-bracing
contributes highest rigidity to the whole platform by retaining the platform until the
highest load reported compare to another configuration.