Seismic

Routines for Simulating Seismic Loading in Wind Turbine Dynamic Analyses

by Dr. Ian Prowell
MMI Engineering

and Mohammad-Amin Asareh
Missouri University of Science and Technology

A module for simulating seismic loads on wind turbines was developed through a subcontract between NREL and Missouri University of Science and Technology. The seismic module is currently implemented as a replacement for the generic user-defined platform loading routine in FAST, UserPtfmLd. All functionality existing in FAST, other than that relying on other platform models, is still intact and functions without modification. This module adds the ability to:

  • Specify a platform motion time series as displacement, velocity, or acceleration independently in the X, Y, and Z axes.
  • Generation of synthetic motion for platform motion time histories.
  • Baseline correct motions to prevent residual displacement and velocity due to numerical error in integration.
  • Perform spectral matching through integration with the 2009 version of RSPMATCH as documented in: Atik, L.A. and Ambrahamson, N. (2010). "An Improved Method for Nonstationary Spectral Matching", Earthquake Spectra, 26(3), pp. 601-617. DOI: 10.1193/1.3459159

The force required to achieve the desired motion is calculated at run time for each time step and applied to the wind turbine platform in FAST using a damped oscillator model.  The current implementation does not directly support consideration of base rocking, twisting or soil-structure interaction.

Through a code-to-code verification, the version published has been shown to reproduce previous work published in:

Powell, I., Elgamal, A., Jonkman, J., and Uang, C. (2010). Estimation of Seismic Load Demand for a Wind Turbine in the Time Domain, National Renewable Energy Laboratory, NREL/CP-500-47536, Golden, Colorado, USA. Also published in: 2010 Proceedings of the European Wind Energy Conference and Exhibition, Warsaw, Poland.

Experimental validation is in the process of being published and will be cited here when available. Existing certification of the FAST code does not apply to modifications provided here.

Examples are provided in the distributed archive that illustrate the different features of the seismic module such as using synthetic motion generation, baseline correction and target response matching. Questions regarding the seismic module or the provided examples should be directed to Dr. Ian Prowell.

You may download the following files from our server:

  • Seismic Change Log (v2.00.00, 1 KB, 01-May-2014)

    This is a list of changes made to the code. Look at this text file to see if we've made worthwhile changes since you received your previous version of Seismic.

  • Seismic Shaking Documentation (v1.00, 625 KB, August-2012)

    This is a document that can be used as a manual for using the seismic module. Input parameters, example files, verifications and recommend practices are described in this documentation. It is also included in the archive.

  • FAST Seismic Archive (v2.00.00, 5.2 MB, 01-May-2014)

    This is a self-extracting archive of FAST with seismic capabilities. It includes the seismic source code, an executable file of FAST v7.02.00d-bjj compiled using Intel® Visual Fortran v11.0.074 with the seismic source code replacing the generic UserPtfmLd routine, seismic shaking documentation and examples for using different features of the seismic module.

Programming Language:     Technology:     Wind and Water Tools:

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If you want to refer to this website in a report, here is a reference you can use:
NWTC Information Portal (Seismic).  https://nwtc.nrel.gov/Seismic. Last modified 19-March-2015 ; Accessed 23-February-2017