40 ksi or 60 ksi rebar
40 ksi or 60 ksi rebar
(OP)
Is there a mojor cost difference between the two grades of rebar?
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RE: 40 ksi or 60 ksi rebar
Dik
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
I don't know the exact cost figures or cost indexes, but I do not think the cost is significant anymore to worry about.
PE, SE
Eastern United States
"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: 40 ksi or 60 ksi rebar
2. Haven't seen 40 KSI called out for many years.
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: 40 ksi or 60 ksi rebar
BA
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
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RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
On topic: I have been requested to use 40ksi bar to save money on ICF walls from a specialty ICF contractor. I don't know if they buy stock by the train car load or what but 1) it is still available (subject to market) 2) there apparently is a price difference to some people (maybe labor only? I know they preferred lots of small bar vs. less big bar)
To the OP: Please post the answer you find after you call.
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MAP
RE: 40 ksi or 60 ksi rebar
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: 40 ksi or 60 ksi rebar
______________
MAP
RE: 40 ksi or 60 ksi rebar
RE: 40 ksi or 60 ksi rebar
I conducted testing on mockups of old bridges. We had to order a special heat of 40ksi steel from the mill (only the stirrups were 40ksi) as no suppliers or mills in the whole state had 40ksi steel. In our material testing, most of the "40 ksi" steel yielded at ~55ksi or so, not too far below 60ksi steel.
I'd be interested if someone has actually seen a recent heat ticket for 40ksi steel and what it's actually yielded at. I think the stuff at Lowes/Home Depot is whatever is cheapest and most regionally available, so in most of the US, 60ksi (I doubt they have a heat ticket to prove it though).
RE: 40 ksi or 60 ksi rebar
Weldability is only assured if the bar is specified ASTM A706 (in Canada it's Type W.) If I recall correctly, there once was a "weldability supplement" that certified A615 as weldable, but the current spec doesn't have one - it is all about carbon equivalent content.
If large post-yield ductility is really a primary concern (it seldom is except in seismic design), you can specify ASTM A706 Grade 60 or 80, which has higher ductility (12-14%) than A615 grade 60 (9%). In these specs, the ductility is dependent on grade and size of the bar. Stainless rebar ductility is a minimum of 20%.
ICF and swimming pool folks like lower yield strength so they can bend it in the field, often by hand. Since to bend it, you have to yield it, they like the low grade materials. This is fine for pools and artistic works. As a designer, you really should design buildings to avoid the need for that, since few field personnel will use the right bend radius, and tighter bends can not only damage the bar, but the CRSI/ACI bends assure that the concrete inside the bend does not crush and cause a bar fracture under heavy stresses. This is the failure mechanism of tighter bends in concrete. We are trying to educate ICF builders about ordering fabricated bar to make the work go faster and safer. The premium to have it fabricated is very small, and is much less expensive than field labor to bend the bar. I hand bent bar on my first ICF project, and it is not the way to go. Detail corner bars and minimum-bend, single leg stirrups to go over openings, and have them fabricated. Many fabrication shops use automatic benders that can knock out a house full of cut to length and fabricated bars very quickly.
The latest data suggests that A615 grade 60 averages 70 ksi, nominal; A615 grade 75 averages a little over 80 ksi; and A706 grade 60 averages under 70 ksi. I do not have figures for grade 40 handy, but most mills do not produce it.
The bar sold in retail centers may be non-spec, ungraded bar, so be careful with that.