To assess high-frequency ship response for rule development purposes of large modern containerships, numerical predictions were compared with experimental data. The numerical results were based on a technique that relied on superimposing rigid body motions on elastic hull girder deformations, whereby a finite element Timoshenko beam idealizing the hull was two-way coupled to a RANS solver for the fluid-structure interaction problem. The experimental data were obtained from model tests of a segmented 10,000 TEU containership equipped with load cells, accelerometers, and pressure sensors. A longterm measurement campaign onboard a 4,600 TEU panamax containership yielded full-scale measurements. For the investigated cases, data analysis confirmed that predictions accounting for highfrequency response yielded higher section loads than those based on rigid body assumptions. The amount of high-frequency excitation may vary for different ship kinds and sizes, ship speeds, loading conditions, and operating areas. Present design rules cannot be changed until the associated uncertainties are clarified.
Size and capacity of containerships have increased rapidly to meet the unceasing growth of marine container transport needs. A ship able to carry 18,000 TEU will soon be built, and designs with a capacity of 22,000 TEU are planned. Although design experience is limited for such ships, design rules are needed to ensure adequate structural safety, and guidelines, together with the necessary software, must be established to aid the designer in specifying wave-induced hull girder loads and the associated high-frequency response caused by the inherent elastic behavior under wave-impact related loads. At present, classification society rules rely on constant overall safety factors to account for the dynamic amplification of stresses in the ship structure. However, full-scale measurement campaigns of, e.g., Kahl and Menzel (2008) and Storhaug et al. (2003) revealed that highfrequency measured vibrations contributed significantly to life-cycle extreme stresses and total fatigue damage.
