Page 84 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

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CONNECTIONS

3.16 CHAPTER THREE

FIGURE 3.10 Typical welded splice of columns when depth D U of the upper col-
umn is nominally 2 in less than depth D L of the lower column.

3.2.5 Bolt Installation: Snug-Tight versus Fully Tensioned

High-strength bolts (A325 and A490) can be installed either snug-tight or fully tensioned. Common
bolts (A307) can only be installed snug-tight. Snug-tight installation is achieved when all plies are
in contact. It can be attained by a few impacts of an impact wrench or the full effort of a person using
an ordinary spud wrench. Fully tensioned installation is achieved when the bolt is stressed in tension
to 70% of its tensile strength. The RCSC Specification requires fully tensioned installation for the
following conditions:
1. Joints in which fastener pretensioning is required in the specification or code that invokes the
Specification
2. Joints that are subjected to significant load reversal
3. Joints that are subjected to fatigue load with no reversal of the loading direction
4. Joints with ASTM A325 or F1852 bolts that are subject to tensile fatigue
5. Joints with ASTM A490 bolts that are subject to tension or combined shear and tension, with or
without fatigue

FIGURE 3.11 Typical bolted splice of columns when depth D U of the
upper column is nominally 2 in less than depth D L of the lower column.

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