However, for steels having a definite yield stress, the stress
be limited to the yield stress; for steels without a definite yield point, the
will stress will be limited to 80 percent of the ultimate strength or 0.2 percent
proof stress whichever is smaller and that in prestressed concrete
members, the tensile stress in the extreme fibres of the concrete may be
permitted so as not to exceed 213 of the modulus of rupture of concrete.