Increasingly, the shapes and sizes of structural steel sections are now dual certified to have a minimum 50ksi yield, i.e. the steel has a yield stress of 50,000 pounds per square inch in both compression and tension.
Grades with a minimum 50ksi include ASTM A572 Gr. 50, A992 Gr. 50, A500 Grades B and C, A529 Gr. 50, and A709 Gr. 50. Before these high yield steels became readily available, A36 with a yield of 36ksi was the standard. The new grades provide weight savings because of their strength. Furthermore, lighter buildings require less extensive and costly foundations.
One of the benefits of steel in construction is that it can be curved to create functional structures with aesthetic appeal. The question arises as to whether the steel with these higher yields limits steel section bending.
The answer is, given the right machinery and rolling techniques, 50ksi steel rolls just as easily as A36. Consequently, the curved sections also have the beneficial strength to weigh ratios inherent in the straight members.
The strength of other materials is less than steel even when enhanced by steel reinforcing. For example, a normal concrete mix has a yield stress of 3 to 5ksi in compression only. Even “high strength” concrete may have a compressive yield strength of only 12 to 15ksi. And the strength to weight ratio of steel is much higher than other materials.’
