清代拱券券形的基本形式

拱券在门洞、无梁殿、桥涵、地宫等建筑及构筑物中应用十分普遍。一般筒拱，按照一定的券形曲线支搭券胎，以楔形券砖或券石砌成。近年发现清代北方官式建筑拱券的券形曲线存在着一个普遍规律，即：拱券矢高（F）与拱券半弦长（R）比值为1.1；圆心偏离对称轴的偏心矩（a）为0.105倍半弦长（R）的双心圆，这是清代北方官式建筑拱券结构最通用的基本形式。

Basic Forms of Masonry Arches in Qing-Style Buildings

Arch is widely used in buildings and structures such as gates, halls without beams, bridges and underground palaces and so on. In recent years, some new discoveries have been made in the study of the arch of the northern official Qing dynasty architecture.