Study On Mechanical Properties Of Dougong And Queti In Timber Structure

The ancient timber structure with long history was a main structural form in ancient China, which is also an important component of Chinese architectural cultural heritage. It has gorgeous graceful shape, ingenious exquisite numerous local structure, rich and rational thought of building structure, which all show the superb art and wisdom of the ancient working people, thus, it enjoys a wide reputation in the history of world architecture. In its local structure, Dougong and Queti has been the typical symbol of Chinese ancient timber structure with their originality.However, many wooden structures have suffered different degrees of damage, because of material performance degradation for the age of wood, rain erosion and earthquakes and some other natural disasters. In wood structure, structural damages often occur in local components, such as Dougong and Queti, utilizing the local damages to consume energy to protect the beam column from collapsing of the whole wooden structure, which reflects the ancients’ well wisdom about building structure. Local damages don’t affect structural normal use seemingly, but it is adverse to the whole structure with its development, so repair and reinforcement to it has been continuously carried out nowadays.To fully excavate structural thought and damage mechanism of ancient timer structure and instruct the maintenance and reinforcement of the wood structure from the point of mechanics and to inherit and protect our country’s precious architectural heritage, our research group has done some research and analysis to Taihao mausoleum buildings based on the “ Twelve-Five-Year ” national science and technology support projects subject( project number:2013BAL01B04) with the principal ot Tai Hao Mausoleum management office in Huaiyang and the institute of ancient building protection in Nanyang City. This paper chose Dougong in the stigma and Queti of Tong Tian Hall as study objects from the degree fo local structure, and conducted static analysis, quasi-static analysis and elastic stability analysis to explore mechanism behavior and hysteretic behavior of Dougong and improvement to structural performance of the timber beam frame with Que-ti. Specific research work is as follows:(1) We conducted field investigation to Tong Tian Hall in Taihao mausoleum in Huaiyang to get the material conditions, basic size and the connection between components and some other construction features of its structure and components by measuring and taking pictures.We made a detailed statistics of Dougong and Queti about their species and number in Tong Tian Hal, and we carefully explored and counted its damage condition. According to the investigation results, we sorted out detailed drawings and tables of the whole structure and local components and their damage status, providing first-hand valuable information for model and analysis.(2) Based on field investigation and related literature, Dougong on the top of column and Queti in junction fo beam and column whose force status were more complex and had good seismic behavior in some degree, so they had significant influence on the wooden frame structure from the perspective of the mechanics analysis, so we chose them as the main research object in this paper. It conducted detailed composition analysis about Dougong and discussed the structural effect fo Dougong.At the same time, it analyzed briefly their components in model and introduced their connection form and structure characteristics about Queti through extensive consulting books about wood structure and particular measured drawings.(3) To explore stress state, weak position and seismic behavior of Dougong in Tong Tian Hall, the paper established entity model of Dougong on the top of column by finite element software ANSYS, considering contact non-linearity and geometric non-linearity and material non-linearity. Through static analysis, it studied the stress state and deformation regularity and found the weak components and positions, which could be used to instruct its repair and reinforcement. Besides, it studied hysteretic behavior of Dougong under vertical and horizontal loads and obtained hysteretic curve, skeleton curve, ductility coefficient,nonlinear coefficient, equivalent stiffness and restoring force model, which quantitatively analyzed seismic behavior of Dougong from different degree, and studied seismic performance in longitudinal and transverse direction by comparison.(4) To explore structural performance of wooden frame and structural function of Queti to it, it established entity model of wooden frame, then it studied stress state of dovetail, beam end and mid-span under ultimate limit state and the influence of Queti to bending, shear, local compression and elastic stability and some other performance of the wooden beam frame through comparative model with Que-ti or not. It fully excavated its scientific connotation, whose result proved that Que-ti is not only a ornamental element, but also its existence is very necessary to the structure.