Allowable Steel Stress in Foundation Hairpin
Allowable Steel Stress in Foundation Hairpin
(OP)
I am looking through a hairpin design example in Alexander Newmans book "Metal Building Systems" and I noticed that he is using an allowable steel yield stress of 24 ksi for rebar. Is this because he is using working loads instead of factored loads or is he trying to limit the cracking in the slab to which the hairpin is connecting? If I am working with factored loads can I not just use 0.9 x 60 ksi x Area of the hairpin to determine the tensile capacity of my hairpin? Asssuming of course that it is properly developed and lapped into the slab reinforcing.
I would greatly appreciate any clarification on this matter.
Thanks!
I would greatly appreciate any clarification on this matter.
Thanks!






RE: Allowable Steel Stress in Foundation Hairpin
RE: Allowable Steel Stress in Foundation Hairpin
All my bar is 60 ksi and since I am using factored loads I have been using the 0.9 x 60 ksi. I guess because the entire book is on metal buildings he is trying to keep things consistent by using allowable stress for the rebar? I am just not used to seeing that since I have only ever worked with the newer ACI codes.
P.S. I'll keep trying on that star.
RE: Allowable Steel Stress in Foundation Hairpin
RE: Allowable Steel Stress in Foundation Hairpin
The 24 ksi is an allowable rebar stress for Allowable Stress Design.
RE: Allowable Steel Stress in Foundation Hairpin
It looks like what you're doing with LRFDS is correct. I wouldn't allow the stress at service to exceed 0.5fy, but that's not in a code anywhere so it isn't mandatory.
RE: Allowable Steel Stress in Foundation Hairpin
As I get more experience, the thing I feel is the most important to me is where I can place the redundancies without a large subsequent charge....this seems to be one of them....but definitely your call...good luck
RE: Allowable Steel Stress in Foundation Hairpin