Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

CFS Roof Trusses

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I recently received information from Unimast Inc. which included CAD CFS roof
truss details. All the deatils included a note stating that all truss
members(chords, verticals and diagonals) shall not include web punchouts. I'm
curious why this is a requirement since the trusses are fabricated using stud
members(CSJ members using Unimast's designation). Said members when used for
exterior wall assemblies are typically furnished with punchouts and are
usually subjected to combined axial and flexural stresses. Is the concern that
punchouts may occur at a panel point? Could not the design documents require
that truss member punchouts not occur within a prescibed distance near the
panel point?

I reviewed the AISI's '"Design Guide For Cold-Formed Steel Trusses" and HUD's
"Prescriptive Method For Residential Cold-Formed Steel Framing(1st edition)".
Neither of said documents preclude the use of web punchouts for truss members.


Charlie Canitz, PE
Bel Air, MD