METRIC DESIGN GUIDE
There are three world steel shape standards:
ASTM A6/A6M (American).
Japanese Industrial Standard (JIS).
Deutsches Instituet fuer Normung (DIN) (German).
A fourth is the BI, or British Imperial. None is dominant worldwide, but each is used
extensively. There is no international standard issued by ISO, the official international
group that develops worldwide standards.
An ISO standard is currently undergoing development, and will probably involve
selection of shapes from the three primary world standards, coupled with elimination
of redundant shapes.
Since no international trend exists on standardization of steel shapes, the American
Institute of Steel Construction (AISC) recommends that metric projects use the same
steel shapes currently used, but use the metric dimensions listed in ASTM A6/A6M.
A6/A6M lists both inch and mm dimensions of shapes. All load and resistance factor
design (LRFD) property, shape, and specification design data are available in metric
from AISC for A6/A6M steel shapes. (Phone orders: AISC, Chicago, IL, 312-670-
Structural calculations done in metric are easier to review and have a lower probability
ASTM A325M and A490M are standards for structural metric bolts. There are seven
standard metric bolt sizes, which replace the nine bolts currently used. Standard sizes
are 16, 20, 22, 24, 27, 30, and 36 mm. Many manufactured products now use metric
fasteners either in part or for all of a product. There are hundreds of firms making
metric fasteners, screws, and bolts