Unlike P-, this type of P-Delta effect is critical to nonlinear modeling and analysis. P- effect, or P-“big-delta”, is associated with displacements relative to member ends. An easier way to capture this behavior is to subdivide critical elements into multiple segments, transferring behavior into P- effect (Powell 2006). So long as a structure adheres to the slenderness requirements pertinent to earthquake engineering, it is not advisable to model P-, since it may significantly increase computational time without providing the benefit of useful information. Typically, P- only becomes significant at unreasonably large displacement values, or in especially slender columns.
