Glued-Rod Insert Geometry for Fast, Void-Free Timber Anchoring
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Solution Overview
Problem
The installation of glued-in rods in mass timber construction is labor-intensive and prone to air pockets in epoxy, alignment issues, and sub-optimal bonding due to the challenges of working with heavy and cumbersome timber components, especially when holes are not vertical, leading to inefficient and time-consuming processes.
Innovation Solution
A glued-rod insert (GRI) apparatus with a cylindrical outer profile, internal bore, and relief channel is used to position and secure threaded rods in wood components, allowing for easy insertion and rotation of the rod while preventing linear withdrawal and facilitating the flow of excess adhesive, which includes deformable projections and a longitudinal groove to manage epoxy flow and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If threaded rods are manually installed in epoxy-filled holes in timber columns, then the rods can be secured to the timber, but the process is labor-intensive and time-consuming
Solution Approach 1:
The threaded rod is pre-assembled with the insertion tool before insertion into the hole. The epoxy is applied to the rod beforehand, and the entire assembly is then inserted as one unit, eliminating the need for manual positioning and securing steps during installation
Solution Approach 2:
The threaded rod is inserted through the hollow insertion tool, which is then inserted into the pre-drilled hole in the timber. The insertion tool acts as a guide and delivery mechanism, nesting the rod within itself during the installation process
2Manufacturing precision
If lower viscosity epoxy is used to fully encapsulate the threaded rod, then better encapsulation is achieved, but the epoxy flows out of horizontal holes
Solution Approach 1:
The hollow insertion tool serves as an intermediary container that holds the epoxy and threaded rod assembly. It prevents the epoxy from flowing out of the hole by containing it within the tool's cavity during insertion and positioning
Solution Approach 2:
The insertion tool changes the effective containment parameters by providing a physical barrier (the tool's walls) that prevents epoxy flow in the horizontal direction while allowing vertical insertion into the hole
3Manufacturing precision
If custom plywood jigs are used to maintain threaded rod alignment, then accurate positioning is achieved, but the device complexity and installation time increase
Solution Approach 1:
The insertion tool provides localized alignment features directly at the insertion point, such as guide edges or positioning surfaces that ensure the rod enters the hole at the correct angle and position, eliminating the need for complex external jigs
Solution Approach 2:
The insertion tool serves multiple functions: it contains the epoxy, holds the threaded rod, guides alignment, and facilitates insertion all in one device, replacing the need for separate alignment jigs and positioning fixtures
4Strength
If heavier timber components are used for mass timber construction, then structural strength is improved, but handling and positioning become more difficult
Solution Approach 1:
The insertion tool is designed to be self-contained, requiring no external support structures or additional equipment. The tool itself provides all necessary functions for rod installation, reducing the need for additional workers or complex positioning equipment when handling heavy timbers
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 GRI significantly reduces installation time, prevents air pockets, and ensures accurate alignment, allowing for faster and more reliable bonding of threaded rods in mass timber construction, with the ability to handle rods in horizontal or tilted orientations without custom jigs, thereby improving construction efficiency.
Implementation Method 1
Curing/setting of an epoxy is generally an exothermic reaction. Heating of an air pocket causes the gas to expand
Data Source
AI summary
A glued rod insert (GRI) for use in mass timber construction including a generally cylindrical collar having: an internal concentric threaded bore for receiving a threaded rod, circumferential ridges or ribs on the exterior for securely seating within a hole drilled in wood, and a relief channel for excess glue. A method using the glued rod insert (GRI) to install threaded rods in wood components in mass timber construction.