The existing equivalent frame methods for lateral displacement analysis of flat-plate structures are one-value stiffness models which do not reflect the realistic response of structures. Based on the experimental data, the procedure for predicting the drift response of flat-plate structures is reviewed and an approach is proposed which accounts for the changes in the stiffness during the loading history. The application of the suggested procedure is demonstrated through examples. Punching failure in a flat-plate structure greatly changes the overall stiffness and results in moment redistribution between various members of the structure. This effect needs to be considered in the nonlinear analysis of flat-plate structures subjected to earthquake loading. A numerical procedure to account for the localized punching failure in calculating the response of flat-plate structures is developed. Furthermore, a hysteresis model suitable for slab-column connections is proposed on the basis of test results and implemented in a nonlinear dynamic analysis program.