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RE: Need "Flitch-plate" design example

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Your point is well taken. By adding the sideplate where we have, we have
only picked up 4' of patio ceiling load leaving the rest of the load
concentrically loaded above. I doubt that there will be much torsional
effect (my intuition) since the opposite side of the original beam is
supporting about 7 feet of tributary ceiling that is flush framed to the
face of the beam. At worst case, the torsional effect of the bracing should
be minimal.
As far as connection, I specified to install the lags 1+ACI- to 2+ACI- from the edge
of the member in order to develop the chord close to the outer axis. I may
have misunderstood your email in regard to laging around the neutral axis.
3/8+ACI- lags require a min of 5/8+ACI- clearance from the edge of the member. With
a bit over 14,000 pounds on the tension side of the beam, I would feel more
comfortable to bring the lags in another inch and add extra lags as needed
and space them six inch on center top and bottom.
Thanks again to everyone for the help

-----Original Message-----
From: T
Sent: Thursday, May 14, 1998 10:21 PM
Subject: Re: Need +ACI-Flitch-plate+ACI- design example


Agreed.  I generally find a greater number of connectors near the end.  I
also usually specify a double (or staggered) row of connectors, not just on
the neutral axis.  The adding of a side plate may, as I noted before, add
torsional complexities due to relative stiffnesses taking the centre of
shear out from the section centroid and therefore needs greater care in
applying simplistic analysis.  Also as you pointed out the stability of the
plate itself may be compromised by being on the outside but again good bolt
detailing can minimize the problem.  I still think that the flitch plate can
be used in most simple cases by considering the collection as a simple
transformed section without too much worry.

Subject: Re: Need +ACI-Flitch-plate+ACI- design example

+AD4-Sorry,  but I always use the critical bolting for either plate buckling or
+AD4-for horizontal shear.  True composite action can only be acheived for
+AD4-horizontal shear transfer.   Otherwise the combined action depends on the
+AD4-end bearing situation and the relative stiffness of the respective
+AD4-This clearly will be satisfactory in many cases.
+AD4-In the case under consideration I assume the an existing timber beam has to
+AD4-be supplemented.  (I have deleted the original message so stand to be
+AD4-corrected.)  In this case the end bearing is likely to be through the
+AD4-timber.  Then a load transfer operation is required for the steel plate to
+AD4-be effective. E.G. jack up the timber beam, fix the flitch plate and
+AD4-the beam for the load transfer onto the composite section.   And for the
+AD4-steel plate to be properly utilised the horizontal shear transfer needs to
+AD4-take place.  At the beam ends I often find that the shear transfer  governs
+AD4-bolt spacing,  and then in the timber/bolt bearing stress.
+AD4-Bruce Shephard, Principal Consultant Seismic Risk
+AD4-Opus International Consultants, New Zealand
+AD4-DD Telephone  4 4717597,  Fax  4 4711397

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