Timber Corner Connection Using Multi-Angle Threaded Screws
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rigid corner connections in timber construction, such as mitered joints, face issues with delamination due to structural defects like knots or finger joints, and require high manufacturing effort for cylindrical pegs, while existing solutions either fail to absorb tensile forces or require pre-drilling for tie rods.
Innovation Solution
A rigid corner connection design using fully threaded screws that absorb transverse tensile forces and compressive stresses by being screwed in at specific angles, both externally and internally, to enhance load-bearing capacity and rigidity, allowing for simpler manufacturing with less material and labor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid corner connections are designed with mitered beams and traditional fastening methods (dowels, finger joints), then the connection structure is simple to manufacture, but the load-bearing capacity and connection rigidity are insufficient and delamination occurs with increasing stress
Solution Approach 1:
The connection system is segmented into multiple functional screw groups: first screws (45° angle) for tensile force absorption, second screws (parallel to joint) for compressive force absorption, and third screws (perpendicular to joint) for additional stability. This segmentation allows each screw group to specialize in specific force types, significantly improving load-bearing capacity while maintaining straightforward manufacturing procedures.
Solution Approach 2:
The invention introduces multi-dimensional force distribution by arranging screws at different angles (45°, 0°, 90°) relative to the beam axis and joint surface. This spatial arrangement transforms the connection from handling forces in one direction to distributing forces across multiple dimensions, thereby enhancing overall connection rigidity and load-bearing capacity without complicating the manufacturing process.
2Force
If traditional corner connections are used with dowels or finger joints, then the manufacturing process is straightforward, but the connections fail to effectively absorb tensile forces parallel to the grain
Solution Approach 1:
The connection design applies local quality by positioning specific screws with specific functions at specific locations: first screws at 45° angles specifically for tensile force absorption, second screws parallel to the joint for compressive forces, and third screws perpendicular to the joint for additional stability. This localized functional assignment ensures optimal tensile force absorption while keeping the overall structure relatively simple.
Solution Approach 2:
The invention changes the parameter of screw orientation angles to optimize force absorption. By setting screws at specific angles (45° for tensile, 0° for compressive, 90° for stability), the connection structure efficiently handles different force components. This parameter optimization improves tensile force absorption capability without significantly increasing device complexity.
3Strength
If multiple screws are installed at different angles and positions, then connection rigidity and load-bearing capacity increase, but the manufacturing complexity and material usage increase
Solution Approach 1:
The screw connection system achieves multi-functionality where a single set of screws performs multiple functions: first screws absorb tensile forces, second screws absorb compressive forces, and third screws provide additional stability. This universal approach allows the connection to handle various force types simultaneously, improving connection rigidity while minimizing the total number of screws and material usage compared to separate connection systems for each force type.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly increases load-bearing capacity and connection rigidity, reduces deformations, and simplifies manufacturing by distributing forces effectively through the arrangement of screws, inducing quasi-ductile load-bearing behavior with visible failure deformations.
Implementation Method 1
fully threaded screws are screwed in from the outside of the corner connection, so that transverse tensile forces occurring parallel to the joint are absorbed under tension
Implementation Method 2
fully threaded screws are screwed into each of the wooden beams parallel to the joint surface of the two wooden beams, which serve to absorb compressive forces
Implementation Method 3
distributing forces effectively through the arrangement of screws, inducing quasi-ductile load-bearing behavior with visible failure deformations
Data Source
Figure 1
Figure 2
AI summary
The joint e.g. butt strap joint (1), has two wooden beams (3, 4) lying one after the other in a longitudinal direction (X) and adjoining with each other at an end in a joint position (2). The wooden beams comprise self-boring full thread screws (7-9). The thread screws are screwed such that the thread screws remove traction force perpendicular to a wooden fiber direction, absorb the traction force parallel to the fiber direction and transfer compression stress perpendicular to the fiber direction. The thread screws (7, 8) extend over edges of the wooden beams and a wood beam plate (6).