THE MECHANICAL MODEL OF ROCKING COLUMNS IN PALACE-STYLE TIMBER FRAMES IN TANG DYNASTY

With a long history, palace-style timber structure buildings in Tang Dynasty, which are represented by the East Hall of Foguang Temple in Shanxi province, have significant historical and cultural values. The horizontally layered structure, including the column frame layer, Tou-Kung layer and roof frame layer, has good seismic performance, in which the rocking resistance of the columns plays an important role. Taking a single column of the palace-style timber frames in Tang Dynasty as the research object, the resistance mechanism of the rocking column under horizontal loading was analyzed. The process of the column rocking was divided into six states. The geometric conditions, equilibrium conditions and stress distribution of the contact surface for each state were obtained considering the stress-strain states of the compression surface of the column ends during rocking and that the timber in compression may induce elastic-plastic strain. The change of the shape of the compression surface of the column ends and the translation of the action points of Ludou and stone base were analyzed in detail. A mechanical model of the lateral force resistance and horizontal displacement of the rocking column was established and verified by a comparison with the results from numerical simulation and existing models. The differences of the lateral resistance of the column frames of different structural configurations in Tang and Song Dynasties were also analyzed. The results provide a theoretical basis for the study of the seismic performance and reinforcement of ancient structures in early historical period.