It is my experience that the total weight of steel drives the costs. Joists
require longer lead time for fabrication and might introduce noticeable
vibration to human occupancy.
For what it counts and without any other criteria to go on I will place my
vote for WF beams and girders used compositely with the deck.
From: Jason Kilgore [mailto:jkilgore(--nospam--at)leok.com]
Sent: Thursday, March 22, 2001 9:35 AM
Subject: Cost Analysis
We currently have a disagreement in our office about relative pricing of
different floor construction methods for office-building type usage (fire-
proofed or not). Most of our work is in the Kansas City area, where unions
rule supreme and labor costs are high.
Both of the owners of my company are adamant about one of the methods,
several of the younger engineers disagree (but are out-ranked, so the
method is used).
If the disagreement continues, I'm going to do a mock building design using
the two methods and have a few construction companies price it.
Here are the two sides of the issue (very generalized). Any comments?
Use WF girders, steel bar joists at 2'0" - 2'6" o.c., with light-gage form
Advantages: Easier installation, lighter & easier-to-handle pieces, cheaper
deck, no shoring.
Disadvantages: Short spans require heavier joists for fire-rating, fire-
proofing more labor-intensive (requires wrapping each joist in mesh),
more pieces to install and fire-proof
Use WF girders, WF beams at 6'0"-8'0" o.c., heavier composite decking.
Advantages: Far fewer pieces, WF beams usually meet min. sizes for fire-
ratings, easier and faster to fire-proof.
Disadvantages: Pieces are larger, installation more difficult, deck far more
expensive, sometimes requires shoring for casting.
Jason W. Kilgore, P.E.
Leigh & O'Kane, L.L.C.