Frequency-domain approach of hydroelastic response for offshore bottom-mounted slender structure

Bottom-mounted slender structures are often flexible enough to induce hydroelastic effect which could change their dynamic properties and affects the resultant response. This study presents a frequency-domain approach to characterise the hydroelastic response as well as wet dynamic characteristics for offshore bottom-mounted structure with arbitrary geometry. The boundary element method associated with Euler-Bernoulli theory is integrated and coupled. The approaches for wet fundamental period, wet damping ratio and hydroelastic response are validated against a benchmark experiment. Results show that surrounding water has obvious influence on the structural period and damping ratio, particularly on damping ratio. The distribution of added mass grows quickly with depth to about z/d = 0.2 and then gradually decreases whereas added damping mainly concentrates near free surface and drops rapidly with depth. If hydroelastic effect is not considered, it could cause considerable frequency-to-frequency errors from −26% to 52% in responses.