Abstract: Bolted joints, which are wildly used in assembly structures, have the significant effect on the dynamic responses of an entire structure. So it is of great significance to study the dynamic behaviors of the joints. Iwan model, which is just an effective model can represent the significant dynamic behaviors of such joints, is thoroughly studied in this paper. The piecewise nonlinear functions of restoring forces of the model in both cases of microslip and macroslip are first derived and normalized when the yield force of the Jenkins elements, which constructed the model, follow a uniform distribution. Based on these functions, the normalized expressions of energy dissipation per cycle of the model are then derived in the cases of microslip and macroslip. Finally, an adjusted Iwan model is also studied. The results of the present study lay a foundation for the future study of the structural damping and dynamic behaviors of the assembly structures.