Example 3111

Given: A column with perforated cover plates is shown in Figure 31.22. As usual, Ky = 1.3, L = 25 ft (7620 mm). Determine the modified effective length factor (Ky)m by considering the shear deformation effect.

Section properties

Iy = 2467 in.4 (1.03 x 108 mm4) If = 35.5 in.4 (1.48 x 106 mm4) a = 30 in. (762 mm) c = 14 in. (356 mm)

FIGURE 31.22 A column with perforated cover plates.

Solution

1. Calculate the shear factor av by Equation 31.114 _ I p2EI / 9c3 \

2. Calculate (Ky)m by Equation 31.107

31.9.5 Built-Up Members with Bolted and Welded Connectors

AISC (1999) specifies that if the buckling of a built-up member produces shear forces in the connectors between individual component members, the usual slenderness ratio KL/r for compression members must be replaced by the modified slenderness ratio (KL/r)m in determining the compressive strength:

1. For snug-tight bolted connectors

2. For welded connectors and for fully tightened bolted connectors

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