P1: GIG GRBT055-COM-A
AISC-Sample (LRFD)
June 17, 2005
206
17:25
Char Count= 0
MATERIAL
[Comm. A3.
TABLE C-A3.1 Minimum Tensile Properties of HSS and Pipe Steels Specification ASTM A53 ASTM A500 (round)
ASTM A500 (rectangular)
ASTM A501 ASTM A618 (round) ASTM A847 CAN/CSA-G40.20/G40.21
Grade
Fy, ksi (MPa)
Fu, ksi (MPa)
B A B C A B C – I and II III – 350W
35 (240) 33 (228) 42 (290) 46 (317) 39 (269) 46 (317) 50 (345) 36 (248) 50 (345) 50 (345) 50 (345) 51 (350)
60 (415) 45 (311) 58 (400) 62 (428) 45 (311) 58 (400) 62 (428) 58 (400) 70 (483) 65 (450) 70 (483) 65 (450)
specification because it is the most readily available round product in the United States. Other North American HSS products that have properties and characteristics that are similar to the approved ASTM products are produced in Canada under the General Requirements for Rolled or Welded Structural Quality Steel (CSA, 2003). In addition, pipe is produced to other specifications that meet the strength, ductility and weldability requirements of the materials in Section A3, but may have additional requirements for notch toughness or pressure testing. Pipe can be readily obtained in ASTM A53 material and round HSS in ASTM A500 Grade B is also common. For rectangular HSS, ASTM A500 Grade B is the most commonly available material and a special order would be required for any other material. Depending upon size, either welded or seamless round HSS can be obtained. In North America, however, all ASTM A500 rectangular HSS for structural purposes are welded. Rectangular HSS differ from box sections in that they have uniform thickness except for some thickening in the rounded corners. ASTM A500 Grade A material does not meet the ductility “limit of applicability” for direct connections in Section K2.3a(12). This limit requires that Fy /Fu ≤ 0.8. In determining that other materials meet the ductility limit, it is important to note that ASTM A500 permits the yield strength to be determined by either the 0.2 percent offset method or at 0.5 percent elongation under load (EUL). Since ASTM A500 materials are cold-formed and have rounded stress-strain curves with no yield plateau, the latter method indicates yield strengths greater than the 0.2 percent offset. The ductility limit is intended to apply to yield strengths determined by the 0.2 percent offset. However, mill reports may indicate the EUL yield, raising concerns that the material does not have adequate ductility. Supplemental tension tests may be required to determine the 0.2 percent offset yield strength. Specification for Structural Steel Buildings, March 9, 2005 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.