Nut Restrainer Structure for One-Sided Steel Bolt Installation
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Solution Overview
Problem
Current nut restrainers in the construction industry face challenges in compatibility with standard hardware and practices, particularly in allowing one-sided installation of high-strength bolted connections without compromising load-carrying capacity or installation tolerances.
Innovation Solution
A nut restrainer design that includes a cavity with deformable or removable elements to accommodate non-concentric bolt insertion, affixed to a substrate plate, allowing lateral movement of the nut to accept bolts while preventing escape and maintaining direct contact between the nut and bolt with the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a nut restrainer is designed to allow lateral movement of the nut to accept non-concentric bolts, then adaptability to installation tolerances is improved, but the nut may escape from the restrainer
Solution Approach 1:
The nut restrainer incorporates a frangible wall with a predetermined break point that distinguishes between acceptable lateral movement (due to non-concentric bolt insertion) and excessive movement (nut escape). The wall provides rotational restraint while allowing controlled lateral displacement, and the frangible portion breaks when lateral movement exceeds the tolerance threshold, thus preventing nut escape while maintaining adaptability to installation variations.
Solution Approach 2:
The frangible wall is pre-configured with a predetermined break point that anticipates the maximum acceptable lateral displacement due to bolt hole radial tolerance. This preliminary design ensures that before the nut can escape, the frangible wall will break, providing a fail-safe mechanism that prevents nut loss while allowing normal installation variations.
2Adaptability or versatility
If standard high-strength bolts and nuts are used, then compatibility with building codes and existing hardware is improved, but installation from one side only is not possible
Solution Approach 1:
The nut restrainer is designed as a separate component that segments the fastening system into two functional parts: the standard high-strength bolt-nut assembly and the restrainer device. This segmentation allows the use of conventional bolts and nuts that comply with building codes while adding the one-sided installation capability through the restrainer, which holds the nut in position on the accessible side before bolt insertion.
Solution Approach 2:
The nut restrainer acts as an intermediary device between the substrate and the standard high-strength bolt-nut assembly. It provides the missing function of one-sided installation by holding the nut in a predetermined position and allowing it to laterally displace during bolt insertion, while the standard hardware maintains compatibility with existing codes and practices.
3Manufacturing precision
If the nut restrainer prevents lateral movement of the nut, then installation precision is improved, but the nut cannot accept non-concentric bolts
Solution Approach 1:
The nut restrainer employs a dynamic design where the frangible wall provides rotational restraint to maintain nut positioning accuracy during normal handling and installation. However, when a non-concentric bolt is inserted causing lateral displacement, the frangible wall allows controlled movement through its predetermined break point, enabling the nut to accept non-concentric bolts while maintaining precision under normal conditions.
Data Source
AI summary
In accordance with one or more embodiments of the invention, nut restrainers and methods of use are presented, particularly as they apply to high-strength bolted connections for steel structures. Nut restrainers may define a cavity that accepts insertion of a nut, and may include deformable or removable centering elements that allow the nut to move laterally to accept a bolt that is inserted non-concentrically with the nut restrainer, and may comprise a mobile central portion and a rigid outer portion; A method of positioning a nut restrainer concentric with a bolt hole accurate to within the radial tolerance of the bolt hole.