P

bi = N pU Lb where N« 4 — 2/n. Using the recommended stiffness equal to twice the ideal stiffness and applying the resistance factor gives

Equation 32.10 is based on equally spaced braces and is unconservative for unequal spacings. The required stiffness for unequal brace spacings can be obtained using Winter's rigid bar model [6]. In this model, the column is represented using rigid links with ficticious hinges at brace locations and the braces are represented using simple springs. Under the applied load, displacements are imposed at brace locations and equilibrium is enforced to obtain This technique is illustrated in Example 32.2. For a single nodal brace at any location along the length of a column, with the longest segment defined as L and the shorter segment as aL, can be conservatively determined using

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