ABSTRACT

In this paper, we present an extension of the alternative environmental contour approach based on inverse first-order reliability theory in a three-dimensional model that accounts for short-term extreme response uncertainties. Subsequently, the long-term extreme tension under wave excitation loads is investigated to evaluate return levels for the design of mooring systems. Tension extreme data are derived from time-domain simulations of a floating coupled system using the peak-over-threshold method to determine short-term load distribution. A linear interpolation scheme is utilised to establish the parametric model using distribution parameters and wave data. Long-term extreme loads are estimated using a simplified discrete approach combined with Monte Carlo simulations, which helps avoid the tedious task of direct integration. The applicability of these load assessment models is demonstrated and discussed using an example of a semi-submersible platform situated at a 500-m water depth, and the results are compared with one- and two-dimensional environmental contour-based models.

摘要

在本文中，我们在考虑短期极端响应不确定性的三维模型中提出了基于逆一阶可靠性理论的替代环境等值线方法的扩展。随后，研究了波浪激发载荷下的长期极端张力，以评估系泊系统​​设计的返回水平。张力极限数据来自浮动耦合系统的时域模拟，使用峰值超过阈值的方法来确定短期负载分布。线性插值方案用于使用分布参数和波浪数据建立参数模型。使用简化的离散方法与蒙特卡罗模拟相结合来估计长期极端载荷，这有助于避免直接积分的繁琐任务。