Dougong

Dougong (斗拱, roughly "cap and arm") is the bracket system of traditional Chinese timber architecture. A large block (dou) sits on top of a column and supports bow-shaped arms (gong), which in turn carry further blocks, arms, beams or purlins. Built up in tiers, the sets spread the load of a heavy tiled roof onto the columns and let the eaves project far beyond the walls. The same principle spread to Korea and Japan, where bracket sets support the roofs of temples and palaces.

How it works

Dougong pieces are fitted by joinery alone, without glue or metal fasteners, and are held together by friction and by the downward weight of the roof. Several interlocking layers spread the load and reduce strain on the beams. Because the joints can slip, rotate and compress slightly, they also absorb energy, and this flexibility is widely credited with helping old halls survive earthquakes.

History

• Origins. Early forms appeared under the Western Zhou dynasty, without fixed rules or ornament. Bracketing was widely used by the Spring and Autumn period (770-476 BCE).
• Tang and Song. Dougong reached its greatest structural importance. Walls were often non-load-bearing, so the outer bracket sets were essential to carrying the roof. Surviving Tang halls include the Great Buddha Hall of Nanchan Temple (782), whose hip-and-gable roof rests on five-tier (puzuo) brackets, and the East Hall of Foguang Temple (857), where each column carries a bracket set built from seven types of bracket.
• Standardisation. The Song manual Yingzao Fashi (1103) set out an eight-rank grading system of timber sizes, known as the cai-fen system, and gave specifications and drawings for bracket sets.
• Ming and Qing. Brackets became smaller, more numerous and more decorative. The Bao'en Temple in Sichuan, built 1440-1446, has 48 types and some 2,200 sets.

Rank and meaning

For long periods the use of bracket sets was restricted, so they came to signal the upper and ruling classes and official or religious buildings. Ordinary houses were built without them.

Regional names

In Japan the equivalent bracket system is called tokyō; in Korea bracket sets are a defining feature of palace and temple halls, developing from simple Goguryeo brackets to multi-bracket systems from mid-Goryeo onward.