# Offshore wind turbine with monopile (DS and p-y curves)

**URL:** <https://forums.nlr.gov/t/offshore-wind-turbine-with-monopile-ds-and-p-y-curves/1122>\
**Category:** Structural Analysis\
**Created:** [May 5, 2015, 5:48pm UTC](https://forums.nlr.gov/t/offshore-wind-turbine-with-monopile-ds-and-p-y-curves/1122 "2015-05-05T17:48:02Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\
**Post date:** [May 6, 2015, 1:52am UTC](https://forums.nlr.gov/t/offshore-wind-turbine-with-monopile-ds-and-p-y-curves/1122/2 "2015-05-06T01:52:16Z")

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Dear Loic,

The forum topic you linked to provides a lot of guidance for introducing a distributed-springs foundation model into FAST v7 through the user-routine UserTwrLd(). As discussed in that topic, the provided UserTwrLd() could be modified for p-y curves in place of simple linear springs. Using your own UserTwrLd() routine will require a recompile of FAST v7 with your UserTwrLd() routine.

More guidance for building a FAST v7 model with a distributed spring or p-y foundation can be found in the following forum topic: [Natural frequency of NREL DS monotower in OC3.](http://forums.nlr.gov/t/natural-frequency-of-nrel-ds-monotower-in-oc3/845/1).

Best regards,

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