Butterfly Joint CLT Panel Joining for Box Building Assembly
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Solution Overview
Problem
Existing methods for constructing box-shaped buildings using cross-laminated timber (CLT) panels face challenges in achieving strong joining without coupling tools and require heavy panels to be assembled with cranes, making manual insertion of tightening members difficult.
Innovation Solution
A box-shaped building unit is formed by arranging CLT panels on a rectangular parallelepiped with a butterfly joint-shaped joining member that consists of two coupled members with bolt/nut configurations, allowing for easy and secure joining of adjacent panels by inserting the joining member into outwardly opened openings on the panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CLT panels are joined by burying holes and rod-like tightening members, then joining strength is improved, but assembly difficulty increases due to heavy panels requiring cranes
Solution Approach 1:
Instead of inserting tightening members from the inner side through burying holes as in conventional methods, this patent inserts the butterfly joint-shaped joining member from the outer side of the CLT panel. The joining member is inserted through openings formed at the outer main surface, allowing assembly without requiring crane assistance for positioning tightening members.
Solution Approach 2:
The butterfly joint-shaped joining member is divided into multiple parts: a first member with a first opening, a second member with a second opening, and coupling parts with bolt/nut configurations. This segmentation allows the joining member to be assembled in stages, improving ease of operation while maintaining joining strength.
2Strength
If conventional joining methods with burying holes are used, then joining strength is achieved, but the number of processing steps increases
Solution Approach 1:
The butterfly joint-shaped joining member integrates multiple functions into a single component: it includes both the joining function through the bolt/nut coupling mechanism and the positioning function through the specifically shaped openings. This merging reduces the number of separate processing steps compared to conventional methods requiring separate burying hole formation and tightening member insertion.
Solution Approach 2:
The openings are pre-formed at specific locations on the CLT panels before assembly, and the butterfly joint-shaped joining member is designed with predetermined opening shapes that match these pre-formed locations. This preliminary preparation simplifies the overall joining process by eliminating the need for complex on-site processing steps.
3Ease of operation
If openings are made wider at the outer main surface side, then ease of insertion is improved, but structural integrity may be compromised
Solution Approach 1:
The openings in the CLT panels are designed with an asymmetric shape: wider at the outer main surface side to facilitate insertion of the joining member, and narrower at the inner side to maintain structural integrity. The butterfly joint-shaped joining member corresponds to this asymmetric opening shape, with its own openings shaped to match, allowing easy insertion while preserving strength.
Data Source
AI summary
Readily joining CLT panels to obtain a box-shaped building unit.An orthogonal part of each surface of a rectangular parallelepiped has a structure wherein a surface of edge of lumber 11s of a CLT panel 11 is made abut on an inner main surface 10i of a CLT panel 10 and joined thereto by a joining member 2 so that a surface of edge of lumber 10s of the CLT panel 10 and an outer main surface 11o of the CLT panel 11 are flush. A joining part by the joining member 2 has a structure wherein the surface of edge of lumber 10s and the inner main surface 10i and outer main surface 10o of the CLT panel 10 are opened so that the outer main surface 10o side is wider than the inner main surface 10i side, the surface of edge of lumber 11s and at least the outer main surface 11o of the CLT panel 11 are opened so that the inner side of the CLT panel 11 is wider than the surface of edge of lumber 11s side, and the butterfly joint-shaped joining member 2 is inserted into the opening of the CLT panel 10 and the opening of the CLT panel 11 from the surface of edge of lumber 10s of the CLT panel 10 and the outer main surface 11o of the CLT panel 11 side.