316 Framed Columns Alternative Methods 3161 LeMessurier Method

Considering that all columns in a story buckle simultaneously and strong columns will brace weak columns (Figure 31.13), a more accurate approach to calculate K-factors for columns in a sidesway frame was developed by LeMessurier (1977). The K value for the ith column in a story can be obtained by the following expression:

where P; is the axial compressive force for member i, subscript i represents the ith column, and P is the sum of axial force of all columns in a story.

where K0 is the effective length factor obtained by the alignment chart for unbraced frames and PL is

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