What is the elongation requirement for ASTM A992 I-beams?

ASTM A992 I-beams (the primary grade for structural steel in the U.S.) require a minimum elongation of 18% for thickness ≤2 inches. Elongation measures ductility-critical for absorbing energy during earthquakes or collisions. This requirement ensures the I-beam can stretch 18% of its original length before fracturing, allowing gradual deformation instead of sudden failure. Thicker sections (2-4 inches) have a 17% minimum, as larger grains reduce plastic deformation capacity. Elongation is tested on specimens from the web, reflecting the section's weakest point under tension.