Zhutouke (柱头科斗栱): The Qing Bracket Set That Carries the Beam Head

The sizes

Liang Sicheng’s table of Qing bracket-set parts (表一) gives the column-top set its own column, in doukou (斗口): the cap block (坐斗) is 4 long, 3 wide and 2 high, against 3 by 3 for a set between columns. The first projecting arm or cantilever is 2 wide, twice the usual 1. The beam head (桃尖梁頭) is 4 wide and 5½ high. Each crossing block (十八斗) is as long as the arm end it sits on is wide, plus 0.8, and 1 high.

Why it is heavier

Liang explains that the column-top set is really the support for the end of the main beam, so its projecting members are doubled in thickness. The upper layers of a normal set are replaced by the beam head itself, which runs out through the set to the eaves.

The crossings

The arms along the façade and the projecting arm still cross in the cap block’s slot with half-laps, as in the set between columns.

Inferred reconstruction (推断复原)

This joint is an inferred reconstruction. It is inferred from: the 柱頭科 column of Liang’s table, his note on the doubled projecting members, and the half-lap rule of the set between columns. Inferred, not sourced: the length of the projecting arm (taken from the set between columns), the width of the crossing block, the hidden pin under the beam head and the length of the beam head; the beam head’s pointed outer end is not shown.

The sizes

Liang Sicheng’s table of Qing bracket-set parts (表一) gives the column-top set its own column, in doukou (斗口): the cap block (坐斗) is 4 long, 3 wide and 2 high, against 3 by 3 for a set between columns. The first projecting arm or cantilever is 2 wide, twice the usual 1. The beam head (桃尖梁頭) is 4 wide and 5½ high. Each crossing block (十八斗) is as long as the arm end it sits on is wide, plus 0.8, and 1 high. (Liang Sicheng, Qingshi yingzao zeli (NLC scan PDF p. 131)).

Liang explains that the column-top set is really the support for the end of the main beam, so its projecting members are doubled in thickness. The upper layers of a normal set are replaced by the beam head itself, which runs out through the set to the eaves.

The crossings. The arms along the façade and the projecting arm still cross in the cap block’s slot with half-laps, as in the set between columns.

The sizes

Liang Sicheng’s table of Qing bracket-set parts (表一) gives the column-top set its own column, in doukou (斗口): the cap block (坐斗) is 4 long, 3 wide and 2 high, against 3 by 3 for a set between columns. The first projecting arm or cantilever is 2 wide, twice the usual 1. The beam head (桃尖梁頭) is 4 wide and 5½ high. Each crossing block (十八斗) is as long as the arm end it sits on is wide, plus 0.8, and 1 high.

Proportions in the model are illustrative.

Common mistakes

• Using intercolumnar (平身科) sizes on a column-top set. Liang’s table gives the column-top cap block 4 by 3 doukou (not 3 by 3) and the first projecting arm 2 doukou wide (not 1).
• Treating arm length, pin, and beam-head length as table values. Cap block, arm width, beam-head width/height, and crossing-block length/height are from 表一; the rest on this page are inferred.
• Reading it as a set between columns. From the front they look alike; the column-top set carries the beam head, which replaces the upper layers. Compare pingshenke.
• Omitting the layer pin under the beam head. The model shows a hidden pin as an inferred seating between the projecting arm and the beam head; do not invent a different fastening and call it sourced.

Related forms

Western and Japanese workshops have relatives that share a geometric idea (scarf, bridle, dovetail, halving, keyed splice) under other names; they are bridges for readers, not claims of descent.

Stay with the Chinese construction on this page before renaming a piece. See also Compare two joints when a look-alike is listed there.