STEEL - Materials for Civil and Construction Engineers - page 98

These are classified as follows:
1. Low alloy

Low carbon Heat treatable

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Plain High carbon

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High strength-low alloy Plain

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Medium carbon Tool

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■ Plain
2. High Alloy

Tool

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Stainless

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Steels used for construction projects are predominantly low- and medium-
carbon plain steels. Stainless steel has been used in some highly corrosive ap-
plications, such as dowel bars in concrete pavements and steel components in
swimming pools and drainage lines. The Specialty Steel Industry of North
America, SSINA, promotes the use of stainless steel for structural members
where corrosion resistance is an important design consideration (SSINA, 1999).
The use and control of alloying agents is one of the most significant
factors in the development of steels with better performance characteristics.
The earliest specification for steel used in building and bridge construction,
published in 1900, did not contain any chemical requirements. In 1991
ASTM published the specification which controls content of 10 alloying
elements in addition to carbon (Hassett, 2003).

3.5

Structural Steel

Structural steel is used in hot-rolled structural shapes, plates, and bars. Struc-
tural steel is used for various types of structural members, such as columns,
beams, bracings, frames, trusses, bridge girders, and other structural applica-
tions (see Figure 3.8).

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3.5.1 Structural Steel Grades

Due to the widespread use of steel in many applications, there are a wide va-
riety of systems for identifying or designating steel, based on grade, type and
class. Virtually every country with an industrial capacity has specifications
for steel. In the United States, there are several associations that write specifi-
cations for steel, such as the Society of Automotive Engineers, SAE, the Amer-
ican Iron and Steel Institute, AISI, and the American Society for Testing and
Materials, ASTM. The most widely used designation system was developed
cooperatively by SAE and AISI based on chemical composition (Key-to-Steel,
2005). However, the materials and products used in building design and con-
struction in the United States are almost exclusively designated by ASTM
specifications (Carter, 2004). ASTM specification names consist of a letter,