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Building Design and Construction Handbook - Merritt - Ventech!

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7.38 SECTION SEVEN<br />

answer requires application of sound judgment based on experiences. Tests <strong>and</strong><br />

studies that have been made indicate that it takes rather small forces to balance the<br />

lateral thrusts of initial buckling.<br />

Figure 7.21 illustrates some of the common situations encountered in presentday<br />

practice. In general, positive lateral support is provided by:<br />

(a) <strong>and</strong> (b) All types of cast-in-place concrete slabs (questionable for vibrating<br />

loads <strong>and</strong> loads hung on bottom flange).<br />

(c) Metal <strong>and</strong> steel plate decks, with welded connections.<br />

(d) Wood decks nailed securely to nailers bolted to the beam.<br />

(e) <strong>and</strong> (ƒ) Beam flange tied or braced to strut system, either as shown in (e)<br />

or by means of cantilever tees, as shown in (ƒ); however, struts should be adequate<br />

to resist rotation.<br />

(g) Purlins used as struts, with tees acting as cantilevers (common in rigid<br />

frames <strong>and</strong> arches). If plate stiffness are used, purlins should be connected to<br />

them with high-strength bolts to ensure rigidity.<br />

FIGURE 7.21 Methods of providing lateral support for beams.

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