北京故宫西华门城楼庑殿顶大木特征分析

Characteristics of the Hip Roof Wooden Structure of the West Gate,The Forbidden City

文章基于故宫西华门城楼实测数据,针对其庑殿顶屋架部分的大木结构特征进行分析。通过比较宋《营造法式》、清工部《工程做法》及各个时代的庑殿顶建筑实例在屋架结构和构造做法上的异同,梳理官式庑殿顶大木结构的演变过程,解读其背后的结构逻辑和做法依据,从而在宋式到清式演变的脉络中讨论西华门城楼庑殿顶大木结构所具有的特征。在此基础上,文章重点关注了西华门城楼山面使用的弯曲顺梁,比照相近时代建筑实例,提出这一做法呈现滞后性,推测西华门屋架保留了万历重修之前的部分构件。

Based on the measured data of the West Gate(Xihuamen) of the Forbidden City, this paper analyses the characteristics of the major wooden structure of its hip roof(wudian). Comparisons of the similarities and differences are made on the hip roof structure and construction practices in Yingzao Fashi(Building Standards) of the Song Dynasty, Gongcheng Zuofa(Structural Regulations) by the Ministry of Works of the Qing Dynasty, and examples of different times, through which the evolution process of the official major wooden structure of wudian roof is analysed, and the structural logic and basis of crafts behind it are interpreted. Thus, the characteristics of the major wooden structure of Xihuamen in the context of the evolution from the Song Dynasty to the Qing Dynasty are discussed. Based on the analysis, this paper focuses on the curved shunliang(longitudinal tie-beam between columns) used on the side elevations of Xihuamen. Compared with the examples of similar times, it points out that this practice appeared in an earlier time, and the roof truss of Xihuamen has retained some components before the reconstruction during the reign of the Wanli emperor(1573–1620).