Regulatory Approaches for Wind Load Assessments of Offshore Structures

Abstract

The need for an accurate or at least conservative assessment of wind loads on offshore structures to ensure adequate safety is acknowledged by all stakeholders. A traditional, empirical method that uses a prescriptive approach has been accepted for many decades. Proposed designs are submitted to a regulatory body to demonstrate that requirements using this method are satisfied. A review verifies that the submission satisfies the standard. However, there are questions with respect to the accuracy of this approach that may lead to over-conservative limits in operation. Alternatives exist to the traditional, empirical method to assess wind loads and moments on offshore structures that use both wind tunnel testing and computational fluid dynamics (CFD). Challenges to the use of the alternatives to the traditional method for wind load assessment for regulatory purposes have often pointed to a lack of demonstrable consistency or inaccuracy. Recent work performed under the guidance of the Offshore Committee of the Society of Naval Architects and Marine Engineers has done much to answer the challenges to wind tunnel testing and CFD. However, given the expertise needed to successfully perform wind load assessments using wind tunnel testing or CFD, a traditional regulatory approach that relies on prescriptive standards for acceptance may not be practical. This paper explores different approaches for rules or regulations that can leverage the outcomes of the recent work with sufficient reliability to assess confidently that standards are satisfied. Methods by which equivalents to prescriptive standards may be evaluated and applied in a regulatory context are discussed. Comparisons with similar approaches formulated for use in other maritime fields are also examined.