rǔfú 乳栿

Note (full)

Rufu 乳栿, literally "infant beam" or "nursling beam" (Hanyu dacidian; Kroll 2015, 391), refers to cross beams that span two rafters, usually with one end located above the eaves puzuo 鋪作 and the other end inserted into an interior pillar. Liang Sicheng suggests that a rufu might also have both ends layered at the top of the puzuo (Liang 1983, 142; Chen 2008). Chen Mingda notes that a rufu should be located on the lowest level of the roof frame (Chen 2010, 196).9

The term rufu is mainly used in the Yingzao fashi. From the Chinese word meaning infant, ru 乳 likely refers to its short length, while fu 栿 indicates that it is a cross beam (also called liang 梁; Hanyu dacidian). According to two illustrations in the Yingzao fashi (YZFS 31.10a-11b), it appears that a rufu could also be located between two inner pillars.10

Outside of the Yingzao fashi, the only other known occurrence of rufu is in the Jinbian 禁扁, a text published in the Yuan dynasty, but the term ruliang 乳梁 can be found in Tang dynasty texts. Ruliang was understood as a short beam in the Ming and Qing dynasty (Tian 1985, 603; Chen 1989, 190). Because the terms liang and fu are interchangeable, rufu and ruliang should have the same meaning.11

一般認為乳栿是長兩椽的梁，一端在外簷斗栱上，另一端插入內柱；或兩端均架於柱上斗栱（梁1983，142）；陳明達還強調乳栿是屋架中位置最下長兩椽的梁（陳 2010，196）。9

“乳栿”一詞主要見於《營造法式》（1103）。乳，有幼小之意；栿，即為梁（漢語大詞典）。在《營造法式》圖樣“十架椽屋前後並乳栿用六柱”和“十架椽屋前後各劄牽乳栿用六柱”裏(YZFS 31.10a-11b)，兩内柱之間長兩椽的梁似也被稱爲乳栿。10

《營造法式》外目前僅知元《禁扁》有：“乳栿，貳栿也。”《唐會要》等書所輯唐《營繕令》有“乳梁”一詞，明《留青日札》釋其為“壓槽枋上短梁”(田 1985，603) 清《格致鏡原》也基本沿用這一說法，指乳梁為“枋上短梁”(陈 1989，190)。而這句話應該是出自《營造法式》卷五：“凡屋内若施平棊。平闇亦同。在大梁之上。平棊之上。又施草栿。乳栿之上亦施草乳栿。並在壓槽方之上。”很可能田藝蘅已不理解《營造法式》中乳栿和草乳栿的關係，但從《留青日札》到《格致鏡原》也可看出保留了乳梁為短小之梁的意思。11

Broad Match: building frame