Study On Seismic And Mechanical Behavior And Their Degradation Of “dougong” Joint Built With Fork Column

Chinese ancient timber structre is the valuable cultural heritage in China and the world, is also an important part of Chinese civilization. The bracket sets layer of buildings is a layer which is between the column layer and the frame or flat layer, is a elastic cushion of beam support layer, one bracket is also called “Dougong”. “Dougong” has the function of supporting the roof or floor, which plays an important role in ancient buildings. Systematic master its structure characteristics and the transmission mechanism of force is an important link, which in integral behavior analysis and safety assessment of ancient timber structre. It is not only protecting the buildings and is the scientific basis of studying, but also is the key to reveal the value of our ancient buildings subject. Bearing capacity of ancient timber structre decreases because of wood properties change, strong earthquake and man-made destruction, and multiple deformation and damage of structure become more and more serious, so it is more difficult to research and protect ancient timber structre. Therefore, it is vital significance that studying the seismic perfoermance of “Dougong”, especially the damaged “Dougong”.In this paper, the “Dougong” joint of Guan Yin Pavilion of Dule Temple was selected as investigated object, which had been widely used in the high-rise structure of timber buildings. Through the model experiment, the theoretical analysis and numerical simulation method, the mechanical properties and seismic performance of “Dougong” had carried on the detailed research. Based on the structure system analysis of Guan Yin Pavilion of Dule Temple, selected the “Dougong” joint of its second layer as the prototype model of experiment. Then reference for other engineering examples, designed different forms of “Dougong” and studied the laws of the seismic performance of different types of nodes.Through horizontal low cyclic loading test of the intact and damaged “Dougong” joint built with fork column, studied the seismic performance of model and their law of bearing capacity and stiffness degradation. Under the joint action of horizontal and vertical load, “Dougong” mainly through fang's bending transferring load, the form of mechanical characteristics are similar to wood bending work. The experimental study got the main failure characteristics of “Dougong”, and through the five models of hysteretic curves, skeleton curves, energy dissipation and the vertical load, researched the general law of seismic performance of intact “Dougong”. Experimental results show that the vertical load has a great effect on the seismic performance of “Dougong” joint. Based on this, three types of damaged model were produced by the method of manual simulation, to simulate corrosion, worm and crack, respectively. Had the performance degradation laws of seismic behavior, and it was carried on the quantitative analysis that bearing capacity and stiffness degradation rule. Studying provides an important reference for the research of the damaged ancient buildings.Through vertical monotonic loading test of the intact and damaged “Dougong” joint built with fork column, studied the vertical load transfer law and the law of degradation in the node. Under the vertical load, “Dougong” mainly through the fork column, fang and cap block transferring loads, its force mechanism is similar to the compression of the horizontal grain of lumber, and cap block's pressure capacity controls the whole vertical bearing capacity of “Dougong” joint. The resuit shows that the method of manual simulation of damage has influence to the elastic stage compression stiffness. The three kinds of damaged models have different compression stiffness, which has bigger influence on the crack model by damage.Through theoretical analysis, had the calculation formula of vertical compression curve of the model, and shows that the destruction of cap block controls its ultimate vertical bearing capacity. Based on the experimental results, it is obtained formula of resistance bending moment-corner of “Dougong” joint built with fork column, and considering the influence of vertical loads. The calculated result was consistent with the experiment, and the revised formula for calculating bending moment more in line with the actual engineering.Two kinds of finite element model of intact and damaged “Dougong” were built by “Abaqus” software. Through the simulation analysis of vertical monotonic loading test, studied “Dougong” joint's performance under vertical load, further confirms the vertical load transfer laws and its spatial characteristics. Based on the finite element simulation method of intact model, damaged finite element model analysis method was established.