Connection structure and method for irregular concrete structures

Precast connection structure for joining irregular columns and roofs using embedded square pipe modules and protruding pin joints

This technology involves creating column members by inserting square pipe modules into irregular column formwork and pouring concrete. For the irregular roof member joints, an internal plate with rebar is embedded, and a lower plate with a protruding end is attached to the exposed surface. The protruding end is then inserted into the square pipe module and secured with a pin, providing a connection structure and method for irregular concrete structures.

While precast irregular concrete structures, which are assembled from factory- or site-produced free-form members, offer high design freedom, they suffer from chronic issues like joint defects. In particular, the irregular underside of roofs and inconsistent column alignment make it difficult to join columns to roofs and predict structural behavior, limiting the ability to ensure structural stability for public use.

This technology features a pair of cylinder members attached to both sides of a square pipe with pin holes, with their end faces shaped to match the irregular surface of the column. After demolding, a pin is inserted from the outside through the cylinder to pass through the square pipe's pin hole and the protruding end's pin insertion hole. The lower plate is welded to the internal plate, and gaps are sealed with caulking. Applicable to curved roof pavilions, exhibition halls, landmarks, and 3D-designed precast buildings, it allows for clear, pin-based rotational connections between irregular surfaces, simplifying structural analysis and on-site assembly.

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Key Features:

• A pipe module inserted into the internal space of a first irregular member formwork, where the inner surface is formed as a designed irregular surface
• A square pipe member with pin coupling holes and a pair of cylinder members whose other end faces, matching the irregular surface, are exposed on the first irregular concrete member
• An internal plate unit embedded in the joint side of a second irregular member formwork, with one side exposed and multiple rebar connected to the other side
• A lower plate unit coupled to one side of the internal plate unit, featuring a protruding end that is inserted into the pipe module and secured with a pin member

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This invention was developed with support from the Ministry of Land, Infrastructure and Transport for the development of 3D printing equipment and production technology for irregular components.

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