Determination of Displacement Ductility Corresponding to Ignoring P-Delta Effects Using Incremental Dynamic Analysis

P–Delta effects are the result of gravity loads acting through the structure's lateral displacement. Although for Columns with small lateral displacement which undergo low levels of nonlinearity it is perfectly acceptable to neglect the P-Delta effect, for columns experience high levels of nonlinearity it is crucial to accurately capture the P-Delta effects. Finding the threshold of safely ignoring P-Delta effects have been subjected to many studies. Incremental Dynamic Analysis (IDA) is a series of nonlinear dynamic analyses of a structure under varying intensities of ground motion record and provides information on the performance of a structure at various stages. This research implements this technique in determination of permissible displacement ductility for ignoring the P-Delta effects by performing IDA with and without P-Delta effects and comparing the obtained IDA curves. For small earthquake record scale factors, the structural response with and without P-Delta effects are reasonably similar, but as ground motions intensifies two graphs start to diverge which means the P-Delta effects is becoming more significant and no longer can be ignored.