Mechanical study on legs of mat supported jack up platform under towing condition

Key words:  mat supported jack up platform  towing  leg  bending moment

Abstract:

Towing condition of the mat supported jack up platform was introduced briefly. Based on the bending moment study on legs of common jack up platform, the bending moment of mat supported jack up platform was studied. Force analysis on jack up platform was made when it was in rolling state. The formulas of inertia bending moment and total bending moment were deduced respectively. Based on these bending moment formulas, the relationship between location of mat and bending moment of leg was researched. The bending moment change of legs in different mat location was studied based on a real jack up platform. A comparison between mat supported and common jack up platform was made at last. Research results show that the existence of the mat can increase the inertia bending moment of the leg at the main deck. If the leg length above the main deck decreases and the distance between the mat and the main deck increases, the bending moment caused by wind force and gravity may increase. Inertia moment is the dominant factor to the variation of the overall moment. The overall bending moment of the leg increases linearly with the decline of the mat.