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NOTE: Designs requiring notch strength or
installation and operation at low temperatures will
require special material selections. Notch strength
will be required based on design geometry or for
dynamically loaded structures. When notch toughness
is required, the supplementary requirements of the
ASTM specification for the steel being considered
should be reviewed and the appropriate supplementary
requirements (ASTM A 6) specified. In designs where
the material will be exposed to temperatures below
freezing, the material type should be checked
against the proposed ambient and working
temperatures for resistance to brittle fracture.
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2.1.1
Structural Steel
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NOTE: ASTM A 36/A 36M is a general purpose
structural grade steel with a minimum yield strength
of 250 MPa 36 ksi. For notch toughness, a low-alloy
steel should be considered. Increased corrosion
resistance in non-marine environments can be
obtained by specifying a minimum copper percentage
of 0.2 percent. Check availability of shapes. Many
are no longer American made.
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ASTM A 36/A 36M.
2.1.2
High-Strength Structural Steel
2.1.2.1
Low-Alloy Steel
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NOTE: ASTM A 572/A 572M steel is available in Grades
345 MPa (number representing yield strength in ksi)
42, 50, 60, and 65, of which only Grades 42 and 50
are used for dynamically loaded structures.
ASTM A 992 covers W shapes (rolled wide flange
shapes) intended for use in building framing. For
S, M, and HP shapes and channels, A36 or A572 Grade
50 should still be specified.
ASTM A 709/A 709M covers carbon and high-strength
low-alloy steel structural shapes, plates, and bars
and quenched and tempered alloy steel for structural
plates intended for use in bridges. Eight grades are
available in four yield strength levels as follows:
36 [250], 50 [345], 50S [345S], 50W [345W], HPS 50W
[HPS 345W], HPS 70W [HPS 485W], 100 [690], 100W
[690W].
Grades 50W [345W], HPS 50W [HPS 345], HPS 70W [HPS
485W], and 100W [690W] have enhanced atmospheric
SECTION 05120
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