Juzhe, literally “raise" and "bend, bow” (Kroll 2015, 226, 596), is a method of positioning the purlins in relation to each other in order to manipulate the slope and curvature of the roof. In premodern literature, the term juzhe only appears in the Yingzao fashi. According to this text, a building’s juzhe is determined through a process called ding ceyang 定側樣 (deciding the side appearance) or dian caojia 點草架 (designating the rough structural frame). During this process, the roof frame would be drawn on a wall plane at a scale of 1:10 (Li 2009, 5.9b). The drawing would then serve as a reference for determining the positions of the purlins during assembly. 4
Juzhe involves two steps, juwu 舉屋 and zhewu 折屋, which are to be performed in this order. Juwu (“raising the roof”) refers to positioning the ridge purlin in order to determine the total height of the roof (H) measured from the top of the eaves purlin to the top of ridge purlin. In the Yingzao fashi, the height of the ridge purlin (or the top of the roof slope) is stipulated according to the different rank of the buildings. The calculation of the height of the ridge purlin (H) is based on the depth of the building (D), measured by the horizontal distance between the front and rear eaves purlins or between the front and back columns if the building does not employ dougong. The height of the ridge purlin can be either 1/3 or 1/4 the building depth, depending on the rank of the building.
Zhewu (“bending” or “folding” the roof) occurs after juwu (“raising the roof”) has been completed and refers to determining the heights of all the purlins under the roof ridge in order to obtain a concave roof slope. Taking half of a building as an example, the distance between the ridge purlin and the eave purlin is divided based on the number of purlins necessary for the structure in question. After determining the height of the ridge purlin, the roof curvature is created by lowering the intermediary purlins from the slope created by casting a straight line from the eaves purlin to the ridge purlin (Figs. Step 2, 3). The top purlins (shangpingtuan 上平槫) are lowered from this slope by 1/10th the vertical distance between the eaves purlin and the roof ridge (h1). For each of the purlins beneath the shangpingtuan, the height is reduced by half of this distance based on a new slope, as shown in Figs. Step 4, 5, and 6. However, few buildings extant today were constructed exactly according to the description of juzhe in the Yingzao fashi. The final step (Fig. Step 7) would be to add a series of rafters between each purlin. These rafters form the substructure for the rooftile layer.
Among scholars of Chinese architectural history, there is no disagreement in the definition and practice of juzhe. However, concerning the description of the method of calculating zhewu, modern scholars usually summarize the concept as a mathematical formula with the height of the ridge purlin (H) as the only variable (Figs. Steps 3-6; Liang 1983, 493; Pan and He 2005, 51-53）The description in the Yingzao fashi may be closer to the craftsmen’s method of working, in which they obtained the distance of every purlin under the upper purlin by “folding in half” (zheban 折半) the distance of the purlin above it and repeating this method until all the eave purlins were positioned.5
現代建築史學者對舉折的涵義、做法沒有疑義。但在對“折屋”計算方法的表述中，採用了與《營造法式》不同的邏輯，將其總結為以脊檩抬起高度（H）為唯一變量的數學公式（梁 1983，493；潘和何 2005,51-53）。而《營造法式》的表述方式，很可能更接近工匠的工作方法，即以上平槫之折的數值折半再折半的方式獲得其下各槫的“折”的數值。5
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- 1 陳. 2010. 《營造法式》辭解, 426.
- 2 LIANG. 2005. Chinese architecture: a pictorial history, 16-17.
- 3 GUO. 1999. The structure of Chinese timber architecture, 229.
- 4 KROLL. 2015. A Student's Dictionary of Classical and Medieval Chinese, 226, 596.; 李. 2009. 營造法式(故宫藏抄本), 5.9b.
- 5 梁. 1983. 《營造法式》註釋卷上, 493.; 潘. 2005. 《营造法式》解读, 51-53.
- 6 GUO. 2002. A Visual Dictionary of Chinese Architecture, 51.
Broad Match: building frame
How to Cite This Entry
Bibliography:ZHUGE Jing 諸葛净 et al., “ 舉折 jǔzhé.” In Architectura Sinica, edited by Tracy Miller. Entry published May 28, 2022. https://architecturasinica.org/keyword/k000223.
About this Entry
Entry Title: 舉折 jǔzhé
Authorial and Editorial Responsibility:
- Tracy Miller, editor, Architectura Sinica
- ZHUGE Jing 諸葛净, associate editor, Architectural Terminology
- ZHUGE Jing 諸葛净 and CHEN Yansiwei 陈寅思危, entry contributors, “ 舉折 jǔzhé”
- Website coordination by Yuh-Fen Benda
- Preliminary research and revision by CHEN Yansiwei 陈寅思危
- Peer review by ATTCAT 2022
- English proofreading by Aurelia Campbell Tracy Miller
- Chinese proofreading by ZHUGE Jing 諸葛净 ZUO Lala 左拉拉
- Data entry by LI Zhixian 李知賢
- Entry of revised data and links by LI Zhixian 李知賢
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