In previous tests of columns under displacement reversals in the inelastic range of response, different arbitrary displacement histories have been used. Comparisons of drift-capacity data from columns tested under different displacement histories can only be made if displacement-history effects are ignored. Possibly because of this reason, currently available methods for column drift capacity ignore displacement-history effects. To investigate whether drift capacity is a function of displacement history, sixteen cantilever columns were tested under various displacement patterns. The test results indicate that column drift capacity is sensitive to displacement history. For columns cycled beyond yield, drift capacity decreases as a function of the amplitude and number of cycles the column has experienced. Based on measurements of average unit strains in the transverse reinforcement, a model is proposed for estimating the drift capacity for a given column under any symmetric displacement pattern.
The essential requirement for a reinforced concrete column of a structure to resist strong ground motion is that it retains a substantial portion of its strength as it experiences displacement reversals in the nonlinear range of response. This study addresses the problem of estimating column deformation capacity considering possible displacement-history effects.