534

4:00

where a is the shear panel length for unreinforced web element, h is the clear distance between transverse stiffeners for reinforced web elements.

For a web consisting of two or more sheets, each sheet should be considered as a separate element carrying its share of the shear force.

For the design of C-section webs with holes, the above nominal shear strength should be multiplied by a factor qs specified in section C3.2.2 of the AISI Specification [7].

6.6.4.3 Combined Bending and Shear

For continuous beams and cantilever beams, high bending stresses often combine with high shear stresses at the supports. Such beam webs must be safeguarded against buckling due to the combination of bending and shear stresses. Based on the AISI Specification, the moment and shear should satisfy the interaction equations listed in Table 6.3.

6.6.4.4 Web Crippling

For cold-formed steel beams, transverse stiffeners are not frequently used for beam webs. The webs may cripple due to the high local intensity of the load or reaction as shown in Figure 6.26. Because the theoretical analysis of web crippling is rather complex due to the involvement of many factors, the present AISI design equations are based on the extensive experimental investigations conducted at Cornell University, University of Missouri-Rolla, University of Waterloo, and University of Sydney under four loading conditions: (1) end one-flange (EOF) loading, (2) interior one-flange (IOF) loading, (3) end two-flange (ETF) loading, and (4) interior two-flange (ITF) loading [7]. The loading conditions used for the tests are illustrated in Figure 6.27.

TABLE 6.3 Interaction Equations Used for Combined Bending and Shear

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