The purpose of this study is to investigate the development of framed structure of the wooden architecture with multiple bracket sets(多包, Dapo) in order to discover the change and the influential factors of wooden architecture which had existed fo...
The purpose of this study is to investigate the development of framed structure of the wooden architecture with multiple bracket sets(多包, Dapo) in order to discover the change and the influential factors of wooden architecture which had existed for a long time in the Korean Peninsula. The appearance of the Dapo-type structure had been due to the development of framed structure of the wooden architecture. This study demands the actual dimension of each member of frame and Youngjo-Cheok(營造尺) for investigating the characteristics of Dapo-type buildings. In conclusion, There is a tendency that the Column-centered structure changed into the Bracket Set[Beam]-centered structure of wooden architecture in the Joseon Dynasty period.
The interior space could be wider by eliminating columns and using beams. And the inner high-columns are not to be arranged coinciding with the outer column line of the side. The Oimokdori(外目道里)-centered structure makes the eaves possible to be longer efficiently, but it is unstable. The Dapo-type architecture is formed as an alternative for making framed structure more stable. There is a tendency that a gabled roof is replaced gradually by a gambrel roof. And a gambrel roof had been constructed by using Chungryang(衝樑, lateral beam) after 1600''s. These development of the frame structure could be described in detail like below.
A diameter of the inner high-columns had been designed larger than other columns before 1600. These tendency changed gradually, and in 1700''s, a diameter of the outer columns was designed larger than that of the inner high-columns. This is an important feature showing that there was a change in critical load path from the inner high-columns to the outer columns. There was a tendency that the proportion of the building whose columns were not in a line increased gradually after 1600''s. In addition, buildings whose Jungdaegong(中臺工) were not in a line with columns appeared in the latter period of Joseon Dynasty.
On the basis of number of the inner high-columns(Koju), the Dapo-type buildings are classified into 4 groups; 2Koju-type, 1Koju-type, (1)Koju-type, and 0Koju-type. Although there had been high proportion of 2Koju-type to the middle age of Joseon Dynasty, that of (1)Koju-type increased rapidly in the latter period of Joseon Dynasty. This phase showed that the Column-centered structure changed into the Bracket Set[Beam]-centered structure.
The sectional area of the beams was determined by their length. Toibo(퇴보, small beam of inner side space) changed into a member having no function for load path. And buildings with a gambrel roof in which a Jongbo(종보, small and high located beam) is added in the sides of a building - so the number of Jongbo(종보) is the number of Dorikan(道里間, the column spacing in the front and the rear of building) plus 1 - made concentrated appearance in the age between 1600''s and 1700''s. And Jungbo(중보, middle beam) is a member of frame that appeared and used in a transitional period between 1600''s and 1700''s. 2Koju-type changed into 1Koju-type and (1)Koju-type during this period. Chungryang(衝樑) is an indispensable member of frame for composing a gambrel roof in the latter period of Joseon Dynasty, which began to be used in 1600''s. And it made the sides of building more stable.
Through examination of 11 buildings where the number of Juganpo(柱間包, a bracket set used in a column spacing) is differently used in the front and the rear of them, it became clear that Juganpo(柱間包) is used as a fastener rather than a load path between two Jusimpo.(柱心包, a bracket set used in the top of a column) And it is clear that composing Dapo(多包) in 4 sides of building for increasing stiffness of corner is the best method to accomplish the purpose of the Dapo-type architecture.
On the basis of the distance between bracket sets(栱包間隔) and the number of Juganpo(柱間包) used in Toikan(退間, inner side space), the Dapo-type buildings are classified into 4 groups ; agree type(A-type), disagree-proportional type (DP-type), disagree-special type(DS-type), and disagree-irrelevant type(DI-type). Although there had been a high proportion of DI-type before 1600, the DP-type increased rapidly and maintain high proportion after 1700. There is high proportion of 2Koju-type in A-type. The distance between bracket sets is an important factor of the floor planning and composing frame in DP-type building, and columns are not in a line. The distance between bracket sets around the Uju(隅柱, a corner column) is same in DS-type. And DI-type with a gabled roof have exactly opposite features to DP-type.
The bracket sets are to be arranged coinciding with the inner frame structure for structural stability in 8 buildings where Juganpo(柱間包) is designed in accordance with Naechulmok(內出目) and Oimokdori(外目道里) in Toikan(退間), as Bulhoisa(佛會寺) Daeungjun(大雄殿) constructed in 1799.
The framed structure of the eaves is classified into 3 types ; Column-centered type(柱心中心形), Oimok-centered type(外目中心形), and Oimok-centered variable type(外目中心變異形). Oimok-centered variable type(外目中心變異形) had been a major type in 1600''s, but Column-centered type(柱心中心形) became a major type after the middle age of Joseon Dynasty. Generally speaking, Column-centered type(柱心中心形) and Oimok-centered variable type(外目中心變異形) were major types of framed structure of the eaves. 2Koju-type is a high proportioned in Column-centered type(柱心中心形), but not used in Oimok-centered variable type(外目中心變異形).
It is found that Jungdori(中道里, a purlin located in the middle of frame) in Oimok-centered type(外目中心形) is closer to the outer column line. Because of the eliminating and moving of the inner high-columns, they are not to be arranged coinciding with the outer column line of the side. The Dapo-type structure is a way to accomplish stability in Oimokdori-centered structure(外目道里中心構造). Juganpo(柱間包) is inserted for the purpose of solving the problem of excessive load on the Oimokdori(外目道里) and Jusimpo(柱心包), and reducing deformation in framed structure. When Juganpo(柱間包) is composed in 4 sides of building as a fastener rather than a load path, the stiffness of corner is increased. In other words, Juganpo(柱間包) composed in 4 sides of building is most effective.
There is a tendency that the building with a gabled roof is decreased, but the building with a gambrel roof is increased. It is found that the Seokarae(서까래) of Gyupcheoma(겹처마) in the front is shorter than that of Hotcheoma(홑처마) in the rear of the building. This is a way to improve the technological and environmental performance. There is a tendency that Sabunbyunjak(四分變作) changed into Sambunbyunjak(三分變作) in 12 of 70 Dapo-type buildings. But 58 Dapo-type architectures applied of simple measure which is based on Youngjo-Cheok(營造尺).