what is the actual yield stress of a992

huangyhg

what is the actual yield stress of a992?
is it higher than the published 50 ksi?  i had testing perfomed on some older beams in an existing building and i was quite suprised by the yield stress numbers.  steel dated 1880s had a yield stress of 38 ksi and steel dated 1940s had a yeild stress of 53 ksi!  that's better than a36 and a992!  this got me wondering, if you sampled several brand new a992 steel beams, would the results all yield approx 50 ksi or would it very from say 50 ksi up to 65 ksi?  just curious if anyone knows if the actual yeild stress is higher than the published 50 ksi of a992.  i would assume so, and that 50 ksi is the mimimum allowed.  thanks.
yes, minimums are listed.
the aisc seismic specification takes this into account, using the expected yield stress for steel when calculating the   
in the last materials report i looked at for one of our projects, yield and tensile strengths of the a992 material was reported.  i saw values as high as 64ksi for yield, with the average being about 58 ksi.