Sergio Zoruba, Ph.D. and Keith A. Grubb, P.E., S.E.
ASTM A992 has become the standard material specification for wide-flange steel shapes. Here’s why.
Forjoints in special moment frames, inelastic deformations in beams and column panel zones are more reliably attained with ASTM A992 wide-flange shapes.
n just five years, ASTM A992 50 ksi steel hasbecome the dominant material specification for wide-flange shapes, solidly displacing ASTM A36 wide flanges. In fact, ASTM A992 is so commonly rolled that it now costs less than ASTM A36 wide-flangeshapes—and you would be hardpressed to find an ASTM A36 wide flange with a yield as low as 36 ksi. Starting in the 1970s, the steel industry in the United States began to use increasing amounts of recycledmaterials in the production of structural shapes. Today’s structural steels consist of more than 95 percent recycled material. The reliance on recycled materials resulted in a trend towards increasedyield strengths. By the 1990s, ASTM A36 material had significantly higher yield strengths—and less ductility, because tensile strength remained essentially constant—than ASTM A36 steel produced in theearly 1970s. To take advantage of this inherent “bonus” strength, the steel industry began to transition towards 50 ksi steel in 1997, with the release of AISC Technical Bulletin No. 3. TechnicalBulletin No. 3 provided special requirements for ASTM A572 grade 50 steel that created a 50 ksi material suitable for both seismic and non-seismic building applications. The bulletin placed an upper limiton yield strength (ensuring ductility) and tightened a few mechanical properties (requirements absent from the A572 specification). In effect, the bulletin created an early version of ASTM A992, whichwas released in 2000. Today’s version, ASTM A992-01, includes a yield strength range of 50 ksi to 65 ksi, a minimum tensile strength
of 65 ksi and a maximum yield-to-tensile strength ratio of...
Leer documento completo
Regístrate para leer el documento completo.