Background to New Edition of API Bulletin 2V: Design of Flat Plate Structures
Authors: Balint Stephen W. , Serrahn Clay S. , Chang Ben C. 
Published: October 2008

API Bulletin 2V-Design of Flat Plate Structures, has recently been revised. This paper discusses the changes made to the bulletin and references test data to support these changes. Particular effort has been made in the areas of bi-axial compression with lateral pressure, and bi-axial compression with or without edge shear. Design factors of safety have been addressed to improve consistency with other established codes of practice. In addition, the bulletin has been updated to provide guidelines for the use of finite elements analysis as the primary source of expected stress information. The philosophy of hierarchical design has been formally included into the bulletin. Consistency in variable names and formulas has been sought in an effort to improve user friendliness. Observations on areas for future research are made.

Introduction

The mid 1980s was a time of change for the oil industry in the Gulf of Mexico. Production opportunities were beginning to emerge in the deeper waters off the continental shelf. The typical fixed jacket drilling and production structures developed for more shallow depths could not be used in this new arena. New structural arrangements were needed.

Floating steel configurations began to be considered for use as production platforms. The combined requirements of resisting the large lateral and in-plane loading while minimizing weight for optimum efficiency lead designers toward stiffened, thinwall panel design. Buckling was recognized as an important aspect in the design of this type of structure, so the ability to predict the buckling capacities of the various components and the composite structure became critical to successful application.

In 1987, API Bulletin 2V, Design of Flat Plate Structures, was developed to provide guidance to designers for these types of applications in conjunction with other applicable codes and standards. The buckling and design formulations included in the first edition of this document were based on the latest information available at the time - mostly classical equations and empirical formulations provided by other codes. In general, the most conservative approach was adopted into the bulletin.

API requires that each of its documents be reviewed every five years to determine the validity of the document. In 1997, a task group made up of members of the offshore community of design engineers was assembled to review the document and recommend to the API Subcommittee 2 whether the document should be revised or withdrawn. The group validated the existence of the document, though identifying areas where revision was needed to ensure a consistent and complete methodology. The Task Group recognized, however, that there were some issues that would require more time to rectify than others, and so two revisions were planned.

The second edition of Bulletin 2V was issued in 2000. It approached the issue of combined in-plane load with lateral pressure, and revised the interaction formulations for edge shear in bi-axially loaded panels.