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RE: Lateral bracing of longspan steel joists

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Talk to an engineer from one or more joist suppliers that serve your area.
They will probably tell you that they would not bid trusses that they
considered to be inadequately braced.  Then you can honestly tell the
architect that he won't get any bids on his project.  He will probably be
more willing to listen to you then.

Roger Davis
SDS Architects Inc.
(yeah, I'm one of them too)

-----Original Message-----
From:	DOLORES (DOLLY) TRIVIZ [mailto:dktriviz(--nospam--at)]
Sent:	Tuesday, December 15, 1998 1:33 PM
To:	seaint(--nospam--at)
Subject:	Lateral bracing of longspan steel joists

Dear Sirs:

I am working on a project in which I have designed lonspan steel joists (70'
span), two configurations--scissors joists 48" deep, and a pitched top chord
joist with a maximum top to bottom chord depth of about 12' at midspan.  I
have specified full depth bridging (diagonal bridging running from top chord
on one joist to bottom chord of adjacent joist) throughout.  The pitched top
chord joist occurs in the middle of the building and supports a moveable
folding door on the bottom chord, and the scissors joists occur on each side
of this joist at about a maximum 13'-6" spacing.

The architect has tried to convince me that we can effectively bridge these
joists with 30" deep bridging throughout, with the bridging being connected
to a "stiff" (how stiff??) member that will  connect the top to the bottom
chords of the joist where the bridging member intersects the joist.  I have
not given my approval because I am not convinced that this constitutes an
effective bridging system that will prevent lateral movement of the top and
bottom chords of the joists.  The roof diafram will consist of plywood.

What are anyone' thoughts to this type of bridging system suggested by the