Dou di zhu

And Yuan Dynasties, the typical Dou-gong style model is designed. The typical Dou-gong style consists of six Pu-zuos with a double Xia-Ang and Tou-xin Zao type in the first Tiao (Fig. 6).Fig. 6Diagram of the typical Dou-gongFull size imageLoad transferring mechanism of Dou-gongExperimental studyThe test of typical Dou-gong under horizontal load is performed first. Chinese fir, the most commonly used material in traditional timber building, was selected in the test. Given the large size of the typical Dou-gong and the limitations of the test conditions, a 1:3 scale model was used.When Dou-gong is subjected to a horizontal load, it will rotate with Lu-dou as a point of support. Thus, the horizontal and vertical displacement of some components of Dou-gong should be constrained. On the other hand, the direction of the horizontal load is divided into x-direction and y-direction. Since the Dou-gongs are connected by several beams to form a structure layer along the y-direction, the horizontal resistance along this direction is very strong. Accordingly, the horizontal repeated load is applied along the x-direction.The test device is determined and shown in Fig. 7. There is a balance system to keep the horizontal actuator level. In the upper and lower Zhu-tou-fang (O-4 and O-5), which are close to the center of mass of the Dou-gong, a long rod is set to extend to the horizontal actuator with unidirectional hinge connection to transfer horizontal loads without additional rotations. For the simulation of vertical roof loads, weight plates were placed on Liao-yan-Fang (O-7), Zhu-tou-Fang (O-6), and Xia-ping-tuan (O-9). Aluminum frames were set up on Liao-yan-Fang (O-7) and Xia-ping-tuan (O-9) to simulate the constraints, so that the loads can transfer through the beams of the aluminum frames as the real condition.Fig. 7Diagram of the horizontal loading test deviceFull size imageWeight plates were placed on O-7, O-8, and O-9 to simulate vertical loads from the roof. The specific value is calculated based on the loading area of these members and the weight of the roof construction. Dou-gong of the mail hall of the Tian-ning temple (Fig. 5c) are chosen as the basis for calculating the loading areas (Fig. 8). The areas of the rectangles are calculated based on the centers of the adjacent members. The loads on the roof, such as the gravity of the tiles, mortar, and sheathing board, is calculated as 2.4 kN/m2 in accordance with the code [18]. The specific value of the vertical loads on O-6, O-7, O-8 is shown in Table 1, and the mass of weight plates is taken upwards based on conservative estimation.Fig. 8Roof loading areas of each memberFull size imageTable 1 Vertical loads calculation resultsFull size tableThree brackets are set at the intersection of the aluminum column and beam: B1 and B2 are connected to the aluminum column to limit the upward displacement of Liao-yan-Fang (O-7) and Xia-ping-tuan (O-9), while B3 is connected to the aluminum beam to ensure that Liao-yan-Fang (O-7) and Xia-ping-tuan (O-9) remain load-bearing during the downward displacement. Lu-dou (D(a)-1) is constrained at the lower

Stress state of each member. For the second type of members in the y-direction, the unit composed of Dou and Gong is simplified into three beam elements on the basis of equivalent stiffness principle. The section size reduction factor varies from 0.39 to 0.47 according to the grade of Cai. (3) For the third type of members, the section size should be defined by considering the stress state of each member. For the first kind, namely O-2, the section size reduction factor can be 0.71–0.85. For the other two kinds, the section size can be determined by the projection area on the force transmission paths. (4) The simplified model of Dou-gong retains good consistency with the experimental model under horizontal load. In general, the simplified model can simulate the mechanical behavior of Dou-gong and is a suitable method for the large-scale structural analysis of the ancient timber buildings in China, Japan, and South Korean. (5) In further research, simplification method for other Dou-gong types, such as Zhu-tou and Zhuan-jiao types will be studied. Availability of data and materialsThe data sets used and/or analyzed during the current study are available from the corresponding author on reasonable request.ReferencesWu YJ, Song XB, Li K (2018) Compressive and racking performance of eccentrically aligned Dou-gong connections. Eng Struct 175:743–752Article Google Scholar Chen Z, Zhu E, Lam F, Pan J (2014) Structural performance of Dou-Gong brackets of Yingxian Wood Pagoda under vertical load—an experimental study. Eng Struct 80:274–288Article Google Scholar Wu C, Xue J, Song D, Ren G, Zhang J (2022) Mechanical performance of inclined Dougong bracket sets under vertical load : experimental tests and finite element calculation. J Build Eng 45:103555Article Google Scholar Cao J, Zhao Y, Liu Y, Lu H, Wang W (2021) Load-carrying capacity analysis of traditional Chinese Dou-gong joints under monotonic vertical and reversal lateral loading. J Build Eng 44:102847Article Google Scholar Meng X, Li T, Yang Q (2019) Lateral structural performance of column frame layer and Dou-Gong layer in a timber structure. Ksce J Civ Eng 23:666–677Article Google Scholar Sha B, Xie L, Yong X, Li A (2021) Hysteretic behavior of an ancient Chinese multi-layer timber substructure : a full-scale experimental test and analytical model. J Build Eng 43:103163Article Google Scholar Sui Y, Zhao HT, Xue JY, Zhang XC (2012) Experimental study on stiffness of Dougong in Chinese ancient buildings. 4th International Conference on Technology of Architecture and Structure (ICTAS 2011)Wu C, Xue J, Song D, Zhang Y (2022) Seismic performance evaluation of a roof structure of a historic Chinese timber frame building. Int J Arch Herit 16:1474–1495Article Google Scholar Xie Q, Wang L, Zhang L, Xiang W, Hu W (2020) Rotational behaviors of fork-column Dou-Gong : experimental tests and hysteresis model. J Perform Constr Fac 34:04020032Article Google Scholar Wu Y, Song X, Gu X (2020) Lateral load-displacement model of Dou-Gong connections based on rocking and racking coordination. J Build Struct 43:197–202+211CAS Google Scholar Wang M, Xu Q, Zhou Q, Chen X, Leng Y, Zhang F (2021) Analysis on hysteretic performance

Shown in Fig. 1c, Dou-gongs in the Dou-gong layer are categorized according to the different constraints: the Dou-gong located above the corner column is called Zhuan-jiao, the Dou-gong located above the side column is called Zhu-tou, and the Dou-gong located above the Fang between columns is called Bu-jian. Bu-jian is the most numerous Dou-gong in the Dou-gong layer, so the study of a typical Dou-gong is carried out based on its features, constraints and loading conditions.As shown in Fig. 2, in this study, a simplified modeling method of Dou-gong is proposed through four stages. In stage I, a typical Dou-gong is designed based on real features by conducting a research on Dou-gongs’ feature in the Chinese traditional timber buildings built in the Song and Yuan Dynasties (960–1368 AD). In stage II, the experimental study and refined finite-element model analysis are carried out to analyze the load transferring mechanism of Dou-gong. The experimental study provides the basis for verification of the simplified model in stage IV, while finite-element analysis provides the basis for the force flow analysis in stage III. In stage III, the simplified method is proposed, which includes extracting simplified model members through force flow analysis, calculating member dimensions and setting constraints and loading conditions. In stage IV, the simplified method is verified by comparing the simplified model with the experimental model. Through this study, for the Dou-gong that is similar in real features to the typical Dou-gong designed in stage I, the simplified method in stage III can be used to establish a reliable and efficient finite-element calculation model.Fig. 2Flow chart of the studyFull size imageTypical Dou-gong model designThis section explores some Chinese traditional timber buildings built in the Song and Yuan dynasties (960–1368 AD). The characteristics of Dou-gongs are sorted out to summarize the typical Dou-gong model.The basic structure of Dou-gongDou-gongs of traditional timber buildings built in the Song and Yuan dynasties are the classic Dou-gongs. They are similar to those in Japanese and South Korean traditional timber buildings. They mainly consist of Dou, Gong, Ang and other additional components (Fig. 3).Fig. 3Dou-gong componentsFull size imageGong can be divided into two types according to position. One is Hua-gong in the x-direction used as a load-bearing member; the other is Heng-gong in the y-direction which plays the stabilization role. Dou is divided into four types, including Lu-dou at the bottom of Dou-gong, Jiao-hu-dou at the end of Gong and Ang, Qi-xin-Dou at the middle of Heng-gong, and San-dou at the end of Heng-gong. Ang is an inclined member, including Xia-Ang and Shang-ang. The other members mainly include Shua-tou, Xue-xie, Hua-tou-zi, Dian mu, and Fang.The progressing layers of Dou-gong’s overhanging are achieved by Hua-gong and Ang. The overhanging from Lu-dou to the inside or outside of Hua-gong or Ang is called a Tiao. Each layer of Dou-gong is called Pu-zuo. It shows the overlapping relationship between Dou, Gong, and other members. In general, the number of Tiao is equal to the number of Hua-gong plus the number of Ang,