12:16 Jan 12 

If the "Tôles Perforées" are sufficiently "Nervurées" to be self-supporting, that could be the answer.

11:30 Jan 12 

Another reference with TPN... Barbara could be onto something!

11:27 Jan 12 

would only refers to the structural elements and not the metal sheeting...normally :)

11:22 Jan 12 

'tôle' is mentioned elsewhere in the document in the context of metal sheeting for the roof, so this could well be it. I think I'll need to double check with the client. Thanks for your suggestions.

11:19 Jan 12 

Perhaps elsewhere in your document?

TPN can be (but in this case it isn't):
tôle plane noire (This one is just about possible.)
Travaux Publics du Nord
Tarif de première nécessité
Taux de protection nominal

11:18 Jan 12 

I suspect that TPN is actually a typo for IPN which is a standard steel section.

I would need more context to provide a correct answer but I suspect that we are referring to some kind of section cut in the IPN beam which is embedded (but in what?)