Abstract
The restoring force characteristics of rotational embedment of wooden joints are very important to evaluate the seismic performances of traditional timber structures. Some characteristics of wooden joints are discussed and Elasto-plastic Pasternak Model is applied to formulate them effectively, taking the strain hardening and the orthotropic properties into account. In the formulation, the stiffness function depending on the strain levels is introduced to express the rotational stiffness simply in both elastic and plastic states. Then the formulation of crosspiece joints is discussed with rotational embedment tests.