Need a book? Engineering books recommendations...

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

RE: Bar Joists parallel to masonry walls

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The two options for this situation are to 1) omit the last joist and use the
wall for bearing or 2) include a joist immediately adjacent to the wall.

If you omit the last joist you can get into problems with construction
staging because the wall must be in place before the deck is placed.

The detail you're looking at is more common.  In reality, the only purpose
of that end joist is to support the deck until the wall is in place.  After
attaching the deck to the wall you have a redundant system - the load is
shared between the joist (spanning 60', in your example) and the deck
(spanning, say, 5').  Because the deck will only allow the joist to deflect
a minute amount, 99% of the load will be carried by the deck.  All you have
to do is locate the SECOND joist such that the deck can span from it to the
wall (watch for snow drift and deck shear), and ignore the first joist in
your calculations.

You need to clearly state on the drawings that the first joist MUST NOT have
any camber for the very reasons you mentioned.  I usually put the camber
note on both the roof plan and the edge details.

---
Jason Kilgore
Leigh & O'Kane, LLC
Kansas City, Missouri
________________________________________
From: Jim Wilson [mailto:wilsonengineers(--nospam--at)yahoo.com] 
Sent: Friday, August 13, 2004 9:55 AM
To: seaint(--nospam--at)seaint.org
Subject: Bar Joists parallel to masonry walls

I am debating two opposing details for placing a bar joist adjacent a
masonry wall.  Its quite common to see bar joists parallel to masonry walls
set off from the wall by 6" or so.  But it seems to me, however that this
will cause installation problems with the metal decking as well as
performance issues under loading.
 
If a 60' span joist has 1 1/2" camber for example, how can the metal decking
be successfully attached to the top of the masonry wall without either
bending the deck or tapering the top of the wall.  This connection is
imperative to transfer diaphragm shear to the shear wall.
 
Secondly, how can the joist deflect under snow/live loads without fatiguing
the deck welds and ultimately causing some type of failure at that location?
 
Am I being too picky or am I just seeing some bad details?  It seems to me
that the joists should be set off from the wall the same distance as the
typical joist spacing to keep the necessary flexibility.
 
Regards. 
 
Jim Wilson, P.E.
wilsonengineers(--nospam--at)yahoo.com
Stroudsburg, PA
 
________________________________________
Do you Yahoo!?
New and Improved Yahoo! Mail - Send 10MB messages!



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********