This section addresses the requirements of BS5950:2000 5.6.3 (and 2.4.2.7) that indicates when a member is determined to be "sway-sensitive" in an axis, one of two methods can be used to account for the secondary effects. The first method is to use effective lengths for the columns, and the second method is to amplify the sway moments in design. In both these cases only a first-order elastic analysis is required. The engineer can assign which method is to be used for each axis of a member through assignment (refer to Sway-Sensitive Design Method (BS5950:2000 Only) ).

For frames more susceptible to second order forces (λ_cr less than 4.0) a second order (P-Delta) analysis is mandated. This analysis should accurately determine the secondary forces that will result from the deformation of the structure, and will result in member forces following the analysis that incorporate these secondary effects. Where a second-order analysis is performed the members are designed according to the amplified sway method as described below. The engineer can indicate that RAM Frame should perform a first or second order analysis by selecting "Ignore P-delta" or "Consider P-Delta" respectively, in the Criteria-General dialog box in Analysis mode, as described on the Criteria section of this manual.

The BS5950:2000 5.6.3 indicates that for sway-sensitive frames one of two approaches should be taken to perform the code check, these are described below.