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RE: New Masonry on Existing Slabs on Grade

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I would suggest using Table 5 (Chapter 5) or Table 6 (Chapter 6) in
Designing Floor Slabs on Grade by Ringo and Anderson. Table 5 is for wall
loads on slabs with a joint (or crack) immediately adjacant to the wall.
Table 6 is for max. uniform storage loads with an unloaded aisle (critical
aisle width) immediately adjacent to the heavy load. The allowable loads
should be very similar (after adjusting for the width of the wall).

Another way to do it is by using beam on elastic foundation. If you have
Enercalc, I believe there is a program that would calculate the moments or
stresses in the unreinforced slab due to the concentrated load.

If you exceed these allowable loads, I would recommend cutting a footing
into the slab.

I hope this helps!

Jim K.

-----Original Message-----
From:	Zachary Goswick [SMTP:ZachG(--nospam--at)]
Sent:	Wednesday, February 20, 2002 4:58 PM
To:	'seaint(--nospam--at)'
Subject:	RE: New Masonry on Existing Slabs on Grade

	I should probably clarify some more.  It is an interior slab on
grade with
a new masonry bearing wall.  I haven't seen any requirements for this
in any code, so I have talked with a couple of other engineers.  Others
said that they have done it two ways.  Either put the masonry walls
the slab or cut the slab and put in a new footing flush with the slab.
ways have worked in the past for load bearing walls.
	If I do not sawcut, then the masonry wall bears directly on the
slab.  The slab
does 2 jobs, it serves as the slab and as the footing (an integral

The problem that I see with this is that the existing slab will crack
possibly on both
sides of the wall, depending on a couple of factors such as slab thickness,
strength, slab reinforcement, soil conditions, wall load, etc.
	One of the problems I see with putting in a footing is that it costs
more than doing
nothing and just resting on the slab.  The other thing about putting in the
footing is that
it then puts a construction joint on each side of your wall, out from the
face of the wall.
In an industrial environment this may be ok, but when you are trying to
reduce the number
of slab joints under tile or some other brittle material in a finished
space, it is not ideal.
	I asked these questions because I was trying to get an idea of what
criteria other
people use to decide when to sawcut and when not to sawcut.  Is this a
judgment call?  For
the responses that said to put a footing in, what did you base this on?
it just because
the wall is a bearing wall, or was there another reason?
 << File: ATT00039.html >>

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