Monopile Design Methodology
For details of the code implementation, please see Monopile Design API.
Overview
This module is based on initial pile dimension calculations from Arany (2017) [1]. Pile dimensions are chosen to withstand the bending moment from the 50-year Extreme Operation Gust (EOG). This corresponds to wind scenario U-3 in Section 2.2.1. This module is not intended to capture the complexities of a full engineering design study for monopiles, but rather broadly capture the scaling trends due to increased site depth, turbine size and material parameters.
The 50-year extreme wind speed can be calculated using the following cumulative density function.
\(U_{10,50-year}=K(-\ln(1-0.98^\frac{1}{52596}))^\frac{1}{S}\)
where \(K\) and \(S\) are the Weibull scale and shape factors respectively.
The mudline bending moment is calculated as:
\(M_{wind,EOG} = \gamma_LF_{wind,EOG}(S + z_{hub})\)
where \(\gamma_L\) is the load factor (defaults to 1.35), \(F_{wind,EOG}\) is the total wind load on the turbine, \(S\) is the water depth at site and \(z_{hub}\) is the hub height of the turbine. The derivation of \(F_{wind,EOG}\) can be seen in detail in the ORBIT technical documentation.
Initial pile dimensions are then calculated using Arany (2017) [1], API (2005) [2], and Poulos and Davis (1980) [3].