in which L is the span length, Mu is the required moment, n is the number of brace points within the span, E is the modulus of elasticity, Iy is the moment of inertia of the minor axis, Cb is the bending coefficient as defined earlier, ho is the distance between the flange centroids, tw is the thickness of the beam web, ts is the thickness of the web stiffener, and bs is the width of the stiffener (or, for pairs of stiffeners, bs = total width of stiffeners). (For ASD, replace Mu in Equation 4.66 by 1.5Ma, where Ma is the required flexural strength based on ASD load combinations.) Strength Requirement for Torsional Bracing

The connection between a torsional brace and the beam being braced must be able to withstand a moment given by


nCbLbr where Lbr is the distance between braces (if Lbr < Lq, where Lq is the maximum unbraced length for Mu, then use Lq). The other terms in Equation 4.68 are defined in Equation 4.66.

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