Jack-up drilling rigs are widely used in offshore oil and gas exploration industry. It is originally designed for use in the shallow waters; there is growing demand for their use in deeper water depth and harsher environmental conditions.
In order to extend the operating range of jack-up units, it has to be designed reliable analysis as well as eliminating excessive conservatism. Jack-up drilling rigs have been designed by using allowable stress design approach. Recently, the class rule has developed specific regulation based on the load and resistance factor design method based on the reliability foundation. This method is statistically based method which utilizes concepts of limit state design. It uses factored loads and employs resistance factors to account for uncertainly in the loads and computed strength of the leg components in jack-up drilling rig.
In order to compare the two methods (ASD-Allowable Stress Design and LRFD-Load & Resistance Factored Design), lattice leg structure was calculated using ASD and LRFD at different environmental load to dead load ratios in order to compare the load to capacity ratios of each method at these varying ratios.
