An Eigenfunction-Expansion Method for Hydroelastic Analysis of a Floating Runway

Abstract

A mat-type very large floating structure (VLFS) is one of the most popular conceptual designs for future floating plants and airports. With its high length-to-draft and breadth-to-draft ratios, a mat-type structure is quite flexible and is vulnerable to dynamic motions caused by waves. As a result, such structures would usually be located near the shore and be protected by a breakwater. Hydroelastic analyses of VLFS have mostly been done under the assumption of 'zero-draft' to achieve numerical efficiency, Recently, a higher-order boundary element method (HOBEM) analysis of MEGA-FLOAT by Hong et al. (2001) showed that the non-zero draft effect may not be negligible in the practical range of incoming wave lengths. The two-dimensional analysis of Kim & Ertekin (2000) also provided a similar conclusion. However, the HOBEM approach could not easily be applied to a full-scale VLFS because of its high demanding computational resources. In the present paper, we extend Kim & Ertekin's eigenfunction expansion method to three dimensions, and provide a more efficient numerical model for the hydroelastic analysis of a mat-type VLFS. The presence of a breakwater and the proximity of a shoreline will also be considered. Validation of the new model is done by comparison with the HOBEM results. The new model is expected to provide a useful method for site selection and preliminary or conceptual design of a mat-type VLFS.