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RE: "z" limit requirement

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But if the structure is exposed to more severe conditions than just the
weather, notice ACI 318-95 Paragraph 10.6.5.  Allowable z could be as low as
95 kips/in.

	-----Original Message-----
	From:	Roger Turk [SMTP:73527.1356(--nospam--at)]
	Sent:	Tuesday, December 08, 1998 7:45 AM
	To:	seaint(--nospam--at)
	Subject:	"z" limit requirement

	Ah, yes!

	The notorious z-limit requirement!

	When the z-limit requirement starts requiring what I consider a
	amount of reinforcing at a ridiculously close spacing, I calculate
the amount 
	of Grade 40 reinforcing that would be required and provide only that
	whether or not the reinforcing supplied is Grade 40 or Grade 60.
	does not have to be calculated for grade 40, therefore implying that
	crack width for reinforcing stressed under service loads up to about
24ksi is 
	not a concern.

	A. Roger Turk, P.E.(Structural)
	Tucson, Arizona

	A. M. wrote:

	. > Hello Everybody,
	. > 
	. > For any concrete beam (floor, roof or grade beams), are we
	. > UBC
	. > 1910.6.4 to ALWAYS check the "z" (distribution of flexural
	. > reinforcement)?
	. > Most concrete beam design softwares and beam design examples
from books
	. > does
	. > not check this. When I design a concrete beam (especially a
grade beam),
	. > most of the time I need a lot more rebar due to the "z"
requirement than
	. > required by  flexure. Should we ALWAYS check them? Or only on
	. > conditions? 
	. > Thanks in advance for the input.
	. > 
	. > A.M.
	. >