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

Re: Retrofit Involving Steel Joists

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Bill:

Most likely the EOR specified certain loads on the joists, which the detailer
copied, which the joist fabricator designed for. IMO over 99% of joist jobs go
that route.  The problem comes, though, for any retrofit or future change.  Most
joist companies do not save their designs longer than a year.  So while you can
rest comfortable that the joists are strong enough to safely support those
original loads, you don't have a clue as to how they will respond to your new
loads.

I do a LOT of joist retrofit design and construction.  The only safe recourse,
unless you get real lucky and find the joist companies' original design, is to
attack the joist with a micrometer - they don't use standard AISC angles.

Good luck,
                      Phil

"Polhemus, Bill" wrote:

> I've got a little job where we must add some medium-heavy (IMO) equipment to
> the roof of an existing building. I know who supplied the roof joists; I
> have the original engineer's drawings where he called out the joists (incl.
> the SP joists for equipment loads at the time the building was designed).
>
> I called the joist manufacturer, and he pointed me back to the steel
> fabricator, saying "he only gave us a fabrication list, he detailed the
> steel".  But a call to the steel guy yields only a finger pointing back the
> other way!  He claims "we wouldn't have done anything different from what
> the engineer prescribed".
>
> Only problem is, this doesn't answer the question of who designed/detailed
> the "SP" joists which are diagrammed on the engineer's drawings.
>
> I want to know who I should expect to have this design data.
>
> Can someone give me some opinions and guidance on this?