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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)compuserve.com]
	Sent:	Tuesday, December 08, 1998 7:45 AM
	To:	seaint(--nospam--at)seaint.org
	Subject:	"z" limit requirement

	Ah, yes!

	The notorious z-limit requirement!

	When the z-limit requirement starts requiring what I consider a
ridiculous 
	amount of reinforcing at a ridiculously close spacing, I calculate
the amount 
	of Grade 40 reinforcing that would be required and provide only that
amount, 
	whether or not the reinforcing supplied is Grade 40 or Grade 60.
Z-limit 
	does not have to be calculated for grade 40, therefore implying that
the 
	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
REQUIRED by
	. > 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
certain
	. > conditions? 
	. > Thanks in advance for the input.
	. > 
	. > A.M.
	. >