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RE: Steel Terminology[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
- Subject: RE: Steel Terminology
- From: "Sprague, Harold O." <spragueho(--nospam--at)bv.com>
- Date: Mon, 3 May 2004 16:11:23 -0500
Placing concrete between the flanges of a wide flange section, wrapping the column, and placing the rest of the slab on grade is a practice employed by some VERY good concrete floor contractors. Kalman Flooring requires the practice. They even place concrete on top of the anchor rods and base plate, and provide a bond breaker over the horizontal surface interface. They then wrap the entire column with closed cell foam so that the concrete slab on grade is not constrained by the columns when the concrete floor slab shrinks. The re-entrant corners in the slab on grade have added rebar. The column is treated as a penetration, and they can (and do) routinely place slabs that are 100 feet from joint to joint in spite of structural columns at about 30’ o.c. Kalman has done this for probably 25 years, and have fewer cracks and more durable industrial slabs on grade. After the slab is cast, they cut the closed cell foam around the columns and place a bead of elastomeric sealant around the column.
I am not aware of anyone doing this for steel columns, filling the area between the steel flanges and then wrapping the column prior to placing the slab-on-grade. My understanding of the standard of practice is to leave a block-out around the entire steel column (a diamond or circle shape as viewed in plan looking downward), place the slab-on-grade and after the structure is fully loaded (dead load for all floor levels above has been placed) then pour in the blockout around the column. The blockout is poured monolithic, pouring inbetween the steel column flanges as well as the entire block-out. The concrete surface can be tooled to help control shrinkage cracks, but I haven't seen anyone do this for steel columns. They just live with any cracking that might occur. When its a square or rectangular concrete column I have seen contractors tool in a crack control joint (recess) at a diagonal to the four corners of the column (It is about 50-50 wheather the contractor places the crack control joints from the four corners of the column in the block-out).
Mike Cochran S.E.
In a message dated 5/3/2004 1:25:03 PM Pacific Standard Time, GSKWY(--nospam--at)aol.com writes:
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