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Building Design and Construction Handbook - Merritt - Ventech!

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7.4 SECTION SEVEN<br />

7.2.1 Grades of Steel<br />

Structural steel grades are referred to by their corresponding ASTM designation.<br />

For example, the most commonly used grade of structural steel is A36, which is<br />

produced to meet the requirements of the ASTM A36 specification. This grade<br />

offers a good mix of strength, weldability, <strong>and</strong> cost. In many designs, this specification<br />

alone will satisfy designers’ needs. Other specifications, such as A53 for<br />

pipe, provide an equivalent grade of steel for that type of product. However, as<br />

loads on the structural elements becomes larger, other grades of steel may become<br />

more economical because of dimensional limitations or simpler fabrication. These<br />

grades provide greater strength levels at somewhat higher costs per unit weight.<br />

AISC recommends certain grades of steel, all of which have desirable characteristics,<br />

such as weldability <strong>and</strong> cost-effectiveness, for use where higher strength<br />

levels are required. The specifications covering these grades are listed in Table 7.2.<br />

Several steels have more than one level of tensile strength <strong>and</strong> yield stress, the<br />

TABLE 7.2 Characteristics of Structural Steels<br />

ASTM<br />

specification Thickness, in<br />

Carbon Steels<br />

Minimum<br />

tensile<br />

strength,<br />

ksi<br />

Minimum<br />

yield<br />

stress,*<br />

ksi<br />

A36 To 8 in incl. 58–80† 36<br />

A529 To 1 ⁄2 in incl. 60–85† 42<br />

High-strength, low-alloy steels<br />

A441 To 3 ⁄4 incl. 70 50<br />

Over 3 ⁄4 to 11 ⁄2 67 46<br />

Over 11 ⁄2 to 4 incl. 63 42<br />

Over 4 to 8 incl. 60 40<br />

A572 Gr 42: to 4 incl. 60 42<br />

Gr 45: to 11 ⁄2 incl. 60 45<br />

Gr 50: to 11 ⁄2 incl. 65 50<br />

Gr 55: to 11 ⁄2 incl. 70 55<br />

Gr 60: to 1 incl. 75 60<br />

Gr 65: to 1 ⁄2 incl. 80 65<br />

A242 To 3 ⁄4 incl. 70 50<br />

Over 3 ⁄4 to 11 ⁄2 67 46<br />

Over 11 ⁄2 to 4 incl. 63 42<br />

A588 To 4 incl. 70 50<br />

Over 4 to 5 67 46<br />

Over 5 to 8 incl. 63 42<br />

A992 Shapes only 65 50<br />

Heat-treated low-alloy steels<br />

A514 To 3 ⁄4 incl. 115–135 100<br />

Over 3 ⁄4 to 21 ⁄2 115–135 100<br />

Over 21 ⁄2 to 4 incl. 105–135 90<br />

* Yield stress or yield strength, whichever shows in the stress-strain curve.<br />

† Minimum tensile strength may not exceed the higher value.

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