Committee I.2: Loads
Authors: Hermundstad Ole Andreas , Chai Shuhong , de Hauteclocque Guillaume , Dong Sheng , Fang Chih-Chung , Johannessen Thomas B. , Morooka Celso , Oka Masayoshi , Prpic-Oršic Jasna , Sacchet Alessandro , Sazidy Mahmud , Ugurlu Bahadir , Vettor Roberto , Wellens Peter 
Published: April 2023

Committee Mandate

Concern for the environmental and operational loads from waves, wind, current, ice, slamming, sloshing, green water, weight distribution and any other operational factors. Consideration shall be given to deterministic and statistical load predictions based on model experiments, full-scale measurements and theoretical methods. Uncertainties in load estimations shall be highlighted. The committee is encouraged to cooperate with the corresponding ITTC committee.

Introduction

The content of this committee's report is composed in accordance with its mandate by the expertise of its members. Compared to previous reports of the Loads committee the structure is slightly altered, while the topics covered remain basically the same, except that the present report covers ice loads more extensively, while giving less attention to hydroelasticity in waves. There is one section for each of the main types of loads acting on a ship or offshore structure. Hence, Section 2 focuses on wave loads, Section 3 on current and wind loads, while Section 4 concerns ice loads. Next, Section 5 is of a more generic character, concerned with characteristic loads and uncertainty. Finally, Section 6 is devoted to special topics, of which there was only one contribution, namely loads on free-fall lifeboats. Within each of the sections 2 – 5 there is generally one part focusing on ships and another part focusing on stationary offshore structures. On the lowest level we have distinguished between the different ways of assessing the loads, namely theoretical/numerical methods, laboratory tests and full-scale measurements, although this subdivision is not followed consistently through all sections. In the section on wave loads, a distinction is made between potential theory methods and field methods. The latter group contains numerical methods for solving the Navier-Stokes equations in some form, assessing the flow in the entire fluid field. Potential formulations normally use boundary element methods, although field methods can also be used with potential theory (e.g, Amini-Afshar et al. 2019).

The committee has performed a benchmark study on heave/pitch motions and vertical bending moments for a large containership at zero speed in steep regular waves. Existing experimental results have been compared with numerical simulations performed by some of the committee members to investigate the performance of various numerical linear and nonlinear methods, ranging from strip theories to SPH and RANSE solvers. This study is presented in an appendix to the report.

To avoid unnecessary overlap with other ISSC committees the focus has been on loads and rigid body responses. Structural dynamic responses, such as springing and whipping of ships, are left to the Dynamic Response Committee, but vortex-induced vibrations of slender structures and ice-induced vibrations are considered in the present report. Loads on offshore wind turbines (OWT) are covered to some extent, although the Offshore Renewable Energy Committee deals with OWT in general.