grades of steel
 

grades of steel
we are looking at changing some structural steel channels 8x11.5 from a36 to a572. our contractor is saying that there is an extra cost from his supplier if we make this change. i was under the impression that the 50 ksi steel was virtually the same or more readily available than the a36 (similar to w shapes).
does anyone have ionformation on this
thanks in advance

from what i've seen, the higher strength steel does cost more. with steel plate (not shapes) it only costs $1.00 more per hundred weight. however, the 36 ksi steel has a good chance of meeting the criteria for astm a572-50. if the channels are already purchased, one option is to have the contractor get the channels reclassified or at least tested to see their yield strength.
hope that helps.
i understand from talking to a number of fabricators that grade 50 channels are quite costly compared to a-36 channels and harder to come by. the wide flange shapes are only being produced as a a992 specification which is a duel certification. what your contractor is telling you sounds correct. aisc has a web site that can answer any steel related question you have. modern steel construction magazine periodically (i think quarterly) publishes a listing of the rolling sizes from all of the major steel producers.