Abstract
The effect of hydroelasticity on local structural response due to measured wave impact loads are discussed. The structure considered are the vertical beams at the upper flare of a SEVAN SSP FPSO. The first method uses a modal method with uniform and constant added mass. The accuracy of this type of calculation is investigated through comparisons with a complete hydroelastic calculation. These hydroelastic calculations account for the load modifications due to the structural response in a consistent manner. This means that the added mass is time dependent and the effect of slam damping is included. As the load modifications due to the structural deformation is primarily a dynamic effect, the effect of hydroelasticity is discussed through dynamic amplification factors (DAF). The analyses show that the calculated DAFs relevant for the measured wave slamming loads are in a range where the simplified method using only uniform and constant added mass overestimates the structural response considerably in most cases. As an example, the responses from the simplified calculations are in the range of 30 to 40% higher than the response from the fully hydroelastic calculations for the two wave slams with the highest pressures.
