What is the function of the bucket arch in the traditional wooden frame system in China?

Under the eaves of Chengtianmen Hall, there are dazzling and orderly arches and beams. Bucket arch is unique in China traditional wooden frame system architecture. It is a wooden member with the characteristics of warping, arching and arching, and is composed of square wooden arched cross bars. The sinus bow appeared in the Western Zhou Dynasty and the Warring States Period. The Tang and Song Dynasties were only to strengthen the overall function of the building structure. Ming dynasty became the main decoration between column net and roof truss. Colorful, overlapping and staggered bucket arches are the transitional parts between the pillars and the roof, which can not only make the eaves extend obliquely outward, but also bear the weight of the roof and disperse it to the pillars. Dougong has been banned from folk use since the development of Tang Dynasty.