advantage of staggering top and bottom rebar

huangyhg

advantage of staggering top and bottom rebar
are there any advantages of staggering the top and bottom matt reinforcing in a suspended slab? i've seen it done this way but can't really visualize how this is better. it seems much harder for setting up the rebar chairs.
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this gives you more coverage for a shorter amount of rebar stepping the area down to half when the moment is low.
it is definately easier than providing 2 separate lengths of rebar.
i have gone to considerable effort in the past to provide optimized reinforcing layouts with staggered top and bottom steel, detailed and rationalized to put every square millimeter to work. only, to arrive on site with complete top and bottom reinforcing mats installed and grizzly old steelfixers shaking their heads at the complicated reinforcing layout provided by the engineer. after several more occurrences and incredulous conversations with steel schedulers a staggered bar has not been specified since.
the current climate of the industry in my region has labor at a premium, to be optimized at the expense of all other parameters.

when you stagger the top and bottom mats, where does the ironworker put his feet?
that is not a problem, the barsetter can see what he is stepping on.  the only feet to worry about are those big ones belonging to the concretors, who are intent on knocking all this reinforcing steel out of their way.