Characteristics of Elasto-Plastic Rotational Embedment of Traditional Wooden Joints and Formulation of Crosspiece Joints

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.

Review on the mechanical models and formulations of embedment of traditional timber joints in Japan

“…In the rotational embedment of the joint, the most important problem is how to assume the embedded surface displacement. Inayama and Tanahashi et al assumed an exponential function for the outside curve of the loading block. On the other hand, Sakata et al assumed the curve a triangular shape.…”

“…Tanahashi et al analyzed the rotational resistance referred to in Figure using the following equations.…”

“…In recent decades in Japan, seismic performance evaluation methods of traditional timber buildings have been actively researched by several institutions and researchers, and useful developments have been obtained to evaluate the seismic performances of traditional timber joints . Some of these studies are related to the mechanical models and formulations of the embedment of column‐ Nuki (tie beam penetrating a column) joints …”

“…As for the mechanical model of the embedment of joints, the mechanism of embedment of joints is primarily owing to the partial compression on continua . An analysis of the partial compression on continua has special difficulties owing to continua.…”

“…In particular, an embedment curve outside the contact area between a beam and a column of a joint is a key point of the embedment. In relation to the partial compression on continua, some suitable mechanical model is required for the formulation of embedment resistances …”