Modified version OpenFAST v2.2.0

This repository contains a modified version of OpenFAST 2.2.0 in which the Subdyn module has been modified to include the two following features:

• Seismic foundation input motions at the base of the support structure.
• A dynamic soil-structure interaction model that employs a Simplified Lumped Parameter Model [1] to represent the lateral, vertical, rocking and torsional impedances of the foundation.

In order to be able to use these features, the following changes have been introduced into the OpenFAST input files:

1. File SubDyn.dat, new line with the variable SeismicInp, indicates if there is a seismic signal.
2. File SubDyn.dat includes other new line Seismic Input File, read the seismic signal input here.
3. Seismic Input File, in the examples seismic_input.dat.
4. The SLPM Coefficients are indicated in File SubDyn.dat, in the line Simplified LPM-Type members properties. The SLPM member must have Flag.1 = SLPM.

Uniform sismic input motions are assumed (i.e., if there exists more than una support, all of them experience the same foundation input motion). On the other hand, the parameters that define the SLPM must be obtained by fitting the target impedance functions.

The original version of OpenFAST 2.2.0 can be found here OpenFAST v2.2.0

[1] Carbonari S., Morici M., Dezi F., Leoni G., A lumped parameter model for timedomain inertial soil-structure interaction analysis of structures on pile foundations , Earthquake Engineering & Structural Dynamics, Vol. 47, 2147-2171.(2018)

[2] Romero-Sánchez C. and Padrón L.A., Implementation of Ground Input Motion and Dynamic Soil-Structure Interaction into Openfast for the Seismic Analysis of Offshore Wind Turbines. Congress on Numerical Methods in Engineering, CMN 2022.

Financing:

• ProID2020010025, funded by Consejerı́a de Economı́a, Conocimiento y Empleo (Agencia Canaria de la Investigación. Innovación y Sociedad de la Información) of the Gobierno de Canarias and FEDER;