Tower Structural Details

Hello everyone,

I am interested in finding out any detailed information (ideally including drawings) regarding the structural design of a monopole tower structure, such as that which may have been used for the N-REL 5MW baseline wind turbine work. (Although I acknowledge that all data I’ve found in the reports using that concept is related to general structural properties only for the purpose of demonstrating the aero-elastic calculations).

My objective is to complete a set of fatigue life calculations for components and details in the tower, for the contribution of loads resulting from an ice sheet interacting with the structure. As such, I’m looking to use “typical” structural details and connections in the assessment of the stresses to demonstrate the nominal and hot-spot stress approaches, in accordance with the various standards and guidelines.

If anyone has information regarding the structural design and construction of a monopole tower design (actual or typical), please let me know. Alternatively, if anyone can suggest any contacts within industry or the community who might be in a position to provide such details, please advise.

Thank you for any help,
Dale Braun

Dear Dale,

While these don’t include details regarding the transition piece and grout, some structural details of the monopile support structure for the NREL 5-MW wind turbine (including diameters, thicknesses, and material properties) are documented in Section 2.1 of the report found here: I can’t think of a public report with more details.

I hope that helps.

Best regards,

HI Jason,

Thank you for the quick reply.

As noted, Section 2.1 of the document referenced describes some general structural parameters (wall thickness, diameters and some material property assumptions). While this will provide some guidance, I am hoping to obtain more detailed information including the size and spacing of any longitudinal (vertical) stiffening; and, size and spacing of any ring stiffeners. Connection details and any welded attachments are also of interest. This level of information will allow for a meaningful evaluation for the fatigue life estimations.

I can make some assumptions based on ‘typical’ construction techniques, but it is preferred to obtain the information directly from applied designs. However, I’ve not come across and published designs (aside from the most general information) and so I suspect I may need to contact either the classification societies or designers directly.

Thank you again.

Kind regards,


The NREL 5MW design was done only in sufficient detail to be modeled by aeroelastic codes. I would be extremely surprised if anyone ever modeled connectors and ladders and such. This turbine will never be built, so such details are not necessary for our efforts.

I doubt any company that actually designed a real tower would be willing to share their detail design documents with you. You may be able to get something like that for an old, discontinued turbine, but it won’t be anything in the multi-MW range.


Hi Jason,

Thank you for your help in the forum.

I run FAST v8 and I need to get responses (forces and displacements) at top of tower. It seems to me that ElastoDyn is dealing with them. I run FAST8 but I can’t find outputs of Elastodyn, it seems that FAST does not generate outputs of Elastodyn. Could you please give me a hint how I can get responses of top of tower in FAST8?

Kind Regards,


Dear Arash,

The desired ElastoDyn outputs should be specified in the “OutList” section at the bottom of the ElastoDyn primary input file. Have you specified the desired outputs there?

The FAST glue code identifies the output channels being written to the global output (.out) file at the bottom of the FAST summary (.sum) file. These should match the number of columns in the global *.out file.

Best regards,

Dear Jason,

Thank you very much for your reply. The problem is solved.


Dear Jason,

I am modelling the OC4 5MW baseline wind turbine (jacket). I modeled the jacket based on the information in SubDyn input file. but I am not sure about TP. I dont know how to connect tower to jacket as there is not any element there to be able to connect them. I am wondering how tower is connected to the top of jacket.

Could you please help me to model the connection between tower and TP a bit. I would really appreciate any word from you in this regard.

Thank you,

Arash Hemmati,

Dear Arash,

In FAST, the interface nodes (at the top of the jacket) in SubDyn are rigidly connected to the platform in ElastoDyn as described in Section 5.4 of the SubDyn User’s Guide and Theory Manual.

A complete FAST model of the NREL 5-MW turbine atop the OC4-jacket is provided as Test21 in the FAST CertTest.

I hope that helps.

Best regards,