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32.5.4 Continuous Systems

Figure 32.6 shows the relationship between brace stiffness and buckling load for a continuously braced column. The exact solution can be approximated using the following equation [3]:

where Pe is the Euler buckling load, L is the column length, and p is the brace stiffness per unit length.

The continuous brace formulation given in Equation 32.12 can also be applied for equally spaced discrete braces by determining an equivalent brace stiffness per unit length, b, using

where n is the number of braces within the column length, L. This method is accurate for two or more discrete braces and is illustrated in Example 32.4.

Corrugated metal deck is a common type of continuous lateral bracing and acts like a shear diaphragm with the properties of a relative brace. The stiffness and strength properties of the metal n

Metal deck

Jreq'd b

F 2Pu

Jreq'd

FIGURE 32.7 Continuous metal-deck bracing.

deck are generally defined in a per unit width basis (e.g., shear stiffness = G' kip/rad per ft width). The bracing requirements for the shear diaphragm can be determined from the relative brace requirements presented in Section 32.5.2, as shown in Figure 32.7. Properties for corrugated deck can be obtained from the Steel Deck Institute Diaphragm Design Manual [7]. The required shear diaphragm stiffness per unit width is

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