Q.: Is there a standard tolerance on straight (not bent) deformed rebars? A recent shipment of 50-foot lengths of Number 18 bars has a slight fixed bend that is definitely an inelastic deformation; the bars are not just sprung. Do we have any justification for rejecting them?
A.: ASTM reinforcing steel specifications A 615, A 616 and A 617 make no references to such tolerances. Fabricating tolerances for bending deformed bars are given in the Concrete Reinforcing Steel Institute (CRSI) Manual of Standard Practice, 23rd edition, 1980, in Chapter 7, pages 7-4 and 7-5. These tolerances, however, refer only to the relatively short lengths of bars used for standard bends and there is no quantitative requirement for the tolerance of straight lengths of deformed bars.
It is common to require that "Bars shall not be kinked." Bars with a kink in them at the time of manufacture normally go to the scrap heap; those with slight bends or twists are ordinarily accepted. Nevertheless, when bars leave the rolling mill they are reasonably straight. It is possible for something to happen to them enroute that might bend them beyond the elastic limit and put a permanent bend or twist in them. However, we know of nothing in any standard specifications to establish a tolerance on the amount of such inelastic bending. Any requirements as to the straightness of bars would therefore have to be written into the specifications and contract documents by the design engineer.