Design Assembled Legs For Offshore Jacket Platform

Lifting device is the important component of the jack-up, it has a complex composition and endures the total weight of the upper mechanical structure. The work scope is usually in the range of 5m-160m under the water, and the amounts of the jack-up is about 48% of all the offshore platforms.Current domestic and international jack-up offshore drilling platforms, applications and development needs increasing the working depth capability, using high-strength steel,and using advanced leg structure and lifting mechanism, etc. In this paper, I analyze the "Shengli 7th" offshore drilling platform and propose offshore drilling platform, jack-type leg assembly of the transformation plan, design basis and design ideas; making connectors for model design and demolition devices; handling devices fabricated leg hydraulic power system part of the design and control system; analyzing the device design load conditions the overall force by ANSYS finite element software, Pin hole stress concentration and contact element analysis; calculate the joint bolt Department pretension, the least rotary joint , finding that the Department of thread root is the most susceptible to deformation of site.This assembly-leg transformation aimed at increasing the platform's operating depth, increase stability when towing. In this paper, the platform transformed the overall modal analysis, transient dynamic analysis and harmonic response analysis. Through modal analysis of the platform structure ,discovering the stiffness and mass distribution of load to avoid the wave resonance; Transient Dynamic Analysis of maximum displacement and stress derived platform; harmonic analysis by harmonic loads in the steady state dynamic response getting the largest value with the variation of load frequency.