Abstract
Tri-axial non-linear restoring force model of reinforced concrete structures is presented in this paper. Uni-axial multi-linear restoring force model are extended to tri-axial by using an analogy to the plastic theory in this model. The restoring force characteristics of the structures are evaluated by separating into two types of characteristics. One type has energy dissipation in hysteresis loop of unloading and re-loading, and the other type has no energy dissipation in hysteresis loop. The restoring force model is able to adapt to various type of RC structural elements like columns, short columns, walls, and so forth, by connecting two types of models in series. One of the difficulties in modeling of RC structures is to express behavior of axial deformation on unloading. In this paper, a method to resolve this difficulty is presented.
