Australia has high-quality offshore wind resources along its extensive southwestern, southern, and southeastern coastlines. The wind is strong and consistent. To harness the abundant offshore wind energy, six prior offshore wind areas have been officially declared by Department of Climate, Change, Energy, the Environment and Water with some located in shallow water.

For offshore wind projects in shallow water, monopiles, which are large-diameter cylinders driven vertically into the seabed, could be a possible foundation choice for supporting offshore wind turbines. Monopiles are designed to support static load, rotor-induced dynamic loads, and environmental loads from wind, currents and waves. In this research, the focus is on wave-induced loads.

Australian wave environments exhibit unique characteristics. Long-period, persistent swell dominates the southern coastline, which makes nonlinear wave effects more pronounced. Experimental studies have shown that nonlinear higher harmonic wave loads can contribute more than 60% of total wave loading under steep, long-period waves. Furthermore, these higher harmonic forces can lead to resonant excitation of structural responses, such as tower bending. Therefore, nonlinear wave loads may have significant implications on both extreme loads and structural fatigue.

The current industry approach may be insufficient to capture these important nonlinear effects. To support the development of the offshore wind industry and the deployment of a large number of turbines, there is a need for an efficient and robust tool to predict wave loads on monopiles with accuracy. This is valuable in optimising monopile design without comprising safety requirements, reducing over-conservatism and lowering cost. Hence, this research aims to:

1. develop a comprehensive understanding of nonlinear wave loads on monopiles,
2. develop and validate a computationally fast and accurate nonlinear model to predict wave loads,
3. apply the model to Australian wave data to perform multi-decadal, design-life wave loads calculations.