Rotational Behavior of Column Footing Joint and Its Effect on the Dynamic Characteristics of Traditional Chinese Timber Structure

Chinese heritage timber buildings are of high historical and cultural values. The column footing joint is an important connection influencing the structural performance under dynamic load. The moment-rotation relationship of a column footing joint is studied and the effects of vertical load and ratio of column height to diameter on its rotational behavior are analyzed. A spring elements model is proposed to simulate the column footing joint and its stiffness matrix can be simplified to include only one stiffness parameter K with some assumptions. A component-based finite-element model of a timber pavilion is then developed to investigate the effect of rotational stiffness on the structural dynamic characteristics. Results show that a heavier vertical load may lead to larger ultimate moment capacity of the joint. The initial rotational stiffness and ultimate moment capacity decrease with increasing column height to diameter ratio. The modal frequency of the structure studied changes remarkably when the rotational stiffness K varies from 104 to 108 N▪m/rad. The column footing joints should be regarded as semirigid connections in the structural dynamic analysis. A field experiment was also conducted to further demonstrate that the rotational stiffness of column footing joint has notable influence on the dynamic characteristics of traditional Chinese timber structure.