Analysis of Full-Scale Hull Girder Loads of a Container Carrier and Its Simulation Using a Nonlinear Seakeeping Program

Abstract

ABS, SHI, and OOCL have been conducting a project on full-scale measurement of hull stress of a container carrier since 2006. A Hull Stress Monitoring System (HSMS) was installed on an 8063 TEU container carrier recording hull girder loads and other navigation data. Vibratory responses of the hull girder were recorded at certain conditions, such as in the limited fetch storm waves in the Mediterranean Sea. The recorded data has been analyzed to determine the level of vibratory responses and the conditions in which they occurred. Since the vibratory response is superposed to the wave frequency component of the hull girder loads, it also affects the statistics of the maximum hull girder loads in waves. The effects of the vibratory responses in the long-term have been investigated for the dynamic Vertical Bending Moment (VBM) and bow acceleration. While the full-scale measurement provides valuable data for what actually happened in real vessel operations, the actual conditions can not be controlled, such as the wave environments or loading conditions. Hence, numerical calculation results are also desirable to investigate the vibratory responses under controlled conditions taking into account the elastic hull girder properties under exact conditions for validation purposes. ABS has been applying a time domain nonlinear wave/body interaction analysis program, NLOAD3D, for the assessment of the structural responses of vessels in large waves. The NLOAD3D program has been further developed to incorporate an elastic beam model to reproduce vibratory hull girder responses, with the simulations being carried out on motions and moments for selected notable events recorded during the voyages. Comparisons of the simulation and the measurement are presented.