Theoretical solutions including the Morison equation have been widely used to estimate the wave forces exerted on offshore structures of vertical cylindrical configuration. However, none of those methods can accurately predict the wave force of the secondary load cycle induced by a steep wave acting on the cylinder. In this study, regular waves of different wave steepness are generated using an experimental wave flume with a piston-type wavemaker, and the forces exerted on the cylinders of three different diameters are investigated. Using the data-fitting method, the difference between the experimentally measured wave force and that calculated by the Morison equation is empirically formulated, and the effects of key non-dimensional parameters on the force difference function are analyzed. The results show that the amplitude and phase of the force difference function are mainly governed by the incident wave condition including the relative depth, relative amplitude, and relative elevation. On the other hand, the effect of the relative radius is negligible when the diameter-to-wavelength ratio satisfies the small-scale structure condition. The proposed equation is valid for predicting the non-breaking regular wave forces exerted on a vertical cylinder when the secondary load cycle occurs and can be utilized in wave-structure interaction problems.

包括莫里森方程在内的理论解已被广泛用于估计波浪力作用在垂直圆柱构型的海上结构上。但是，这些方法都不能准确预测由作用在气缸上的陡波引起的二次负荷循环的波动力。在这项研究中，使用带有活塞式造波器的实验波形水槽产生了不同波陡度的规则波，并研究了施加在三种不同直径的圆柱体上的力。使用数据拟合方法，根据经验公式化了实验测得的波力与由莫里森方程计算的波力之差，并分析了关键的无量纲参数对力差函数的影响。结果表明，力差函数的振幅和相位主要受入射波条件的影响，包括相对深度，相对振幅和相对高程。另一方面，当直径/波长比满足小尺寸结构条件时，相对半径的影响可以忽略。所提出的方程对于预测二次载荷循环发生时施加在垂直圆柱体上的不破坏规则波浪力是有效的，并且可以用于波浪结构相互作用问题。当直径/波长比满足小尺寸结构条件时，相对半径的影响可以忽略不计。所提出的方程对于预测二次载荷循环发生时施加在垂直圆柱体上的不破坏规则波浪力是有效的，并且可以用于波浪结构相互作用问题。当直径/波长比满足小尺寸结构条件时，相对半径的影响可以忽略不计。所提出的方程对于预测二次载荷循环发生时施加在垂直圆柱体上的不破坏规则波浪力是有效的，并且可以用于波浪结构相互作用问题。