Effects of Damage and Repairs on the Lateral Load Capacity of a Typical Template-Type Offshore Platform

摘要

Damage and defects in the structures of offshore platforms can develop during design, construction, operations, and / or maintenance. Corroded members, cracked joints, dented and bent members are the results. This paper explores the effects of such damage and defects on the lateral loading capacities of a conventional steel 8-leg template-type platform. The computer program ULSLEA (Ultimate Limit State Limit Equilibrium Analyses) is used to evaluate the effects of damage to and defects in the critical load carrying members in such platforms. The effects of repairs on the lateral loading capacities are also studied. The results from the numerical analyses indicate that this type of platform is very robust. This type of platform can tolerate very significant amounts of damage to important load carrying members and not suffer significant decreases in the lateral load carrying capacity of the structure system. The analyses indicate that the robustness in these structures is derived from a combination of redundancy (alternative load paths), 'excess' capacity in the important load carrying members, and ductility (ability to deform plastically without loosing strength). Grouting repairs are indicated to be particularly effective in restoring the capacities of damaged and defective braces and joints.