The design load from waves on offshore structures are often estimated by aid of experimental studies in wave flumes and basins. When going from open sea to laboratorial conditions a number of factors are either added or omitted such as wind above waves. The paddle-generated waves are based on a spectrum taking the indirect effect of wind into account, whereas the direct effect of wind is left out. Previous studies have focused on the direct effect of wind on waves themselves, but no investigations on the load have been made. The question is whether or not airflow separation, vortexes etc. in the wind field alter physical properties such as steepness of waves, the number of breaking waves and hereby the force; especially the in-line force. To investigate the matter, an experimental study of depth-integrated force on a circular cylinder from irregular waves both with and without wind above, was conducted. An objective, when conducting the tests, was to achieve the same significant wave height whether wind was present or not. Exceedance probability curves for wave crest height, depth-integrated force and pressure were obtained. Moreover, a more descriptive assessment of the phenomena was done by studying the average force shape of the hundred largest force events. In addition, there was applied a phase-based harmonic separation method to explore the wind's effect on the harmonic force components of higher order. The front steepness of the waves was clearly increased with the introduction of wind and further increased, when increasing the wind velocity. The introduction of wind consistently increased the number of breaking waves detected with a breaking criterion. The wave-induced load in the tail of the exceedance probability curve was only increased for some of the sea states, when wind was present. This was very dependent on the size of the crest height of the largest breaking waves. The maximum wave-induced pressure in the tail of the exceedance probability curve was on the contrary increased for all sea states, when wind was present, and it kept increasing with increasing wind velocity. For one of the sea states with increased force extrema, the averaged force shape for the hundred largest events of a case with wind revealed a shape with a spiky peak consistent with that generated from breaking waves. This was not present for the case without wind. The separated harmonic contents of the force up to fourth order also showed a tendency towards more energy at harmonic components of higher order for the case with wind.

海上结构的波浪设计载荷通常通过波浪槽和盆地的实验研究来估计。当从公海到实验室条件时，会添加或省略许多因素，例如波浪上方的风。桨产生的波浪基于将风的间接影响考虑在内的频谱，而忽略了风的直接影响。以前的研究集中在风对波浪本身的直接影响上，但没有对载荷进行调查。问题是风场中的气流分离、涡流等是否会改变物理特性，例如波浪的陡度、破浪的数量以及由此产生的力；尤其是内联力量。为调查此事，对来自上方有风和无风的不规则波浪作用在圆柱体上的深度积分力进行了实验研究。进行测试时的一个目标是，无论是否有风，都能达到相同的有效波高。获得了波峰高度、深度积分力和压力的超越概率曲线。此外，通过研究一百个最大力事件的平均力形状，对现象进行了更具描述性的评估。此外，还应用了一种基于相位的谐波分离方法来探索风对高次谐波力分量的影响。随着风的引入，波浪的前陡度明显增加，并在增加风速时进一步增加。风的引入不断增加了用破碎标准检测到的破碎波的数量。当存在风时，超出概率曲线尾部的波浪诱发载荷仅在某些海况下增加。这在很大程度上取决于最大破碎波的波峰高度的大小。在所有海况下，当风存在时，超越概率曲线尾部的最大波浪诱导压力反而增加，并且随着风速的增加而不断增加。对于力极值增加的海况之一，在有风的情况下，一百个最大事件的平均力形状显示出具有尖峰的形状，与破碎波浪产生的形状一致。在没有风的情况下不存在这种情况。