Wall Bracket Assembly With Boss-Receptacle Shear Isolation
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Solution Overview
Problem
Existing methods for connecting steel structures to reinforced concrete structures, such as using post-installed concrete anchors or embedding steel plates, face challenges like rebar interference, complex installation, and potential weakening of concrete, as well as impracticalities in integrating bracketry during concrete pouring.
Innovation Solution
A bracket assembly design featuring a base plate with receptacles and bosses that distribute shear loads, allowing fasteners to experience only tensile forces while reacting shear forces through the interaction between bosses and receptacles, enabling efficient load distribution and higher load-carrying capacity with smaller, lighter components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If post-installed concrete anchors are used to connect steel bracket to concrete, then the bracket can be installed after concrete construction, but the anchors may hit rebar during drilling, have low capacity, and require complex installation procedures
Solution Approach 1:
The base plate is embedded in the concrete during the concrete pouring process itself, before the bracket needs to be installed. This preliminary action eliminates the need for later drilling through rebar and avoids the complexity of post-installation anchoring while ensuring reliable connection from the start.
Solution Approach 2:
The connection system is divided into two functional parts: the base plate embedded in concrete that handles positioning and initial anchoring, and the bracket assembly that provides the actual structural connection. This segmentation allows each component to be optimized for its specific function.
2Strength
If steel plates are embedded in concrete and welded to bracket, then the bracket can be securely connected to concrete, but tremendous welding on site is required and heat from welding can damage the concrete
Solution Approach 1:
The welding operation is replaced with a mechanical bolted connection between the bracket and base plate. The base plate remains embedded in the concrete without welding, eliminating heat damage risks while the bracket connects to the base plate through high-strength bolts, providing secure mechanical attachment.
3Loss of time
If bracketry is integrated with forms during concrete pouring, then post-pour addition is avoided, but nothing can project through the forms making it largely impractical
Solution Approach 1:
The base plate serves as an intermediary element that is embedded in the concrete during pouring, while the actual bracket assembly can be attached afterward. This intermediary approach allows the bracketry to be integrated with the concrete structure without requiring projection through the forms, maintaining both timing efficiency and form compatibility.
4Ease of operation
If fasteners are used to secure mounting plate to base plate, then the bracket assembly can be connected, but fasteners subjected to shear loads experience higher stresses reducing capacity
Solution Approach 1:
The shear load function is extracted from the fasteners and transferred to the boss-receptacle interface. The fasteners are taken out of the shear load path entirely, experiencing only tensile forces, while the bosses and receptacles handle all shear forces through their mechanical interaction.
Data Source
AI summary
A bracket assembly isolates shear forces from fasteners to realize the full tensile load capability of the fasteners. The fasteners extend from a base plate and are embedded within a structure such as a poured concrete wall. Receptacles defined by the base plate receive bosses which extend from a mounting plate which overlies the base plate. The fasteners also retain the mounting plate to the base plate. Shear forces applied in the plane of the mounting plate are reacted between the bosses and the receptacles, the fasteners being isolated from the shear forces using oversized holes in the mounting plate to ensure that the fasteners experience primarily tensile loads.