Mitigation of hydroelastic response in pneumatically supported floating structures

Abstract

Pneumatically supported floating structures, which utilize an aircushion below the structural bottom, have been suggested to remedy the excessive hydroelastic response of the conventional pontoon-type floating structures. This paper presents an analytical study to examine the hydroelastic responses of the pneumatically supported floating structures. For the hydroelastic analysis, the fluid was modeled as a 2D-strip of finite depth seawater, whilst the floating structure was modeled as a beam with zero-draft. A direct coupled model was then constructed by using the boundary integral formulation for the fluid and FEM for the structure and by incorporating a pneumatic factor at the fluid-structure interface to consider the compressibility of the aircushion. Additionally, hydroelastic responses of the pneumatically supported type were compared for the pontoon-type for a wide range of pneumatic factors and regular waves. As a result, the pneumatic supports could significantly reduce the hydroelastic responses in most cases and that the response reduction may be markedly enhanced when the pneumatic factor was taken as small for a relatively short incident wave. Substantially, the analytical technique used in the present study can examine the design conditions, as being essential for practical applications of the pneumatically supported floating structures.