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RE: positive connection for wood beams to columns

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See 1633.2.5 of UBC and 1620.2.4 of IBC.

The IBC is much clearer about the requirements and not as conservative.
I use toe nails or clip angles to the top plate for flush beams to
provide this "positive" connection. 

Also I think there was an errata in the UBC changing the 0.5Ca to 0.3Ca
which for some reason was not picked up in the 2001 CBC.

Michael Bryson, SE


-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
Sent: Tuesday, June 27, 2006 7:34 PM
To: SEAINT
Subject: Re: positive connection for wood beams to columns

Drew:

One possibility in the 1997 UBC might be section 2314.  This is a
section
on post-beam connections.  It states "Positive connection shall be
provided to ensure against uplift and lateral displacement."

Bascially, the provision is for a wood beam that sits on some support in
bearing (i.e. like most floor joist sit on foundation sill plates; like
most roof rafters/joists sit on wall top plates).  Since by and large
the
best way to do a wood connection is to use a bearing or seat connection,
this type of situation is quite common.  The point is that the code does
not want that wood beam to "passively" sit on the bear seat, but wants
there to be some sort of "positive" connection.  In otherwords, it is
not
a good idea to just rely on gravity to keep the beam sitting in place
with
only friction holding it in place...the code wants there to be some sort
of physical connection other than just friction.

In the case of a joist hanger (or something similar), there are usually
nails that "positively" connection the joist/beam to the joist hanger
and
another set of nails (or screws) that connect the joist hanger to the
supporting member.  In the case of joists sitting on a beam or a sill
plate or wall top plate, toe nails are frequently used (although this
may
not be the best choice), but a better thing would be some sort of a
"Simpson" style strap (aka "hurricane straps").

HTH,

Scott
Adrian, MI


On Tue, 27 Jun 2006, Drew Morris wrote:

> In the IBC/UBC in the wood section, there is a comment to the effect
> that "all beams will have a positive connection to the supporting
> column".  Does anyone know where this section is and what is meant by
> positive connection?  Obviously, some sort of Simpson column cap will
> qualify, but would toenails?  There is no uplift on these beams and
they
> are not part of the lateral system.
>
>
>
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