Rebar Anchorage Device Using Segmented Jaw and Tapered Bore
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Solution Overview
Problem
Existing methods for connecting mechanical anchors to steel rebars embedded in concrete structures require special equipment and tools, increasing construction costs and project duration, and can stress the rebar during installation, especially when the rebar length projecting from the concrete is unpredictable.
Innovation Solution
A mechanical rebar anchor comprising a cylindrical barrel with a tapered bore and segmented jaw, a disk-shaped resistance lid, and a helically-wound spring, which allows for quick connection without special tools by applying an axial pushing force through a threaded bolt, creating a wide bearing surface without adding tension to the rebar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a wide head is formed on the rebar to increase bearing surface, then the rebar can better withstand tensile loads, but special equipment and tools are required which increases construction cost and project duration
Solution Approach 1:
The anchorage device is divided into multiple components: a barrel that fits over the rebar end, a resistance lid that creates bearing surface, and a segmented jaw with multiple wedges that grip the rebar. This segmentation allows each component to be simple and inexpensive while collectively providing the required bearing surface capacity without needing complex special equipment
Solution Approach 2:
The anchorage device is designed to be self-installing using only the rebar itself as the installation tool. The segmented jaw automatically grips the rebar when the resistance lid is pressed against the barrel, eliminating the need for external special equipment and tools, thereby reducing construction cost and project duration
2Ease of manufacture
If the rebar is headed prior to installation, then the heading process is simpler, but the precise length of projecting rebar is difficult to predict resulting in preformed heads being cut off
Solution Approach 1:
The resistance lid is pre-formed with a bearing surface area larger than the barrel opening. This preliminary design ensures that even if the rebar length varies or is cut shorter than expected, the lid will still contact the rebar and create the necessary bearing surface, eliminating the risk of preformed heads being cut off
Solution Approach 2:
The bearing surface area of the resistance lid is deliberately made larger than the barrel opening diameter. This parameter change provides a margin of error that accommodates variations in rebar length and cutting precision, ensuring the anchorage device functions correctly regardless of exact rebar dimensions
3Strength
If special equipment is transported into the field for post-installation treatment, then the rebar can be treated to better resist tensile loads, but construction speed decreases and cost increases
Solution Approach 1:
The anchorage device enables workers to install the bearing surface enhancement using only the rebar itself as the installation tool. The segmented jaw automatically engages when the resistance lid is pressed into the barrel, allowing rapid installation without transporting special equipment to the field, thereby maintaining high construction speed while achieving improved tensile load resistance
Solution Approach 2:
The anchorage device components are designed as simple, inexpensive items that can be quickly installed and discarded or left in place. The barrel, lid, and segmented jaw form a simple assembly that provides the required strength without needing expensive specialized equipment, enabling fast installation that maintains construction productivity
4Strength
If a mechanical anchor is connected to increase bearing surface, then the rebar can withstand tensile forces, but the connection process may stress or load the rebar
Solution Approach 1:
Instead of pulling or tensioning the rebar to install the anchor (which would stress the rebar), the resistance lid is pressed inward against the barrel to install the segmented jaw. This inverted approach uses compression rather than tension, allowing the rebar to remain unstressed during installation while still achieving the bearing surface enhancement needed for tensile force capacity
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
Enables reliable connection and increased bearing surface for the rebar to withstand tensile forces without requiring special tools or equipment, ensuring the rebar is not stressed during installation and maintaining stability under compressive and cyclic loading.
Implementation Method 1
A helically-wound spring is positioned at the top of the tapered bore of the barrel to lie between the lid and the relatively wide top end of the tapered segmented jaw of the rebar anchor
Implementation Method 2
The wedges of the jaw are configured to surround and grip the rebar. To this end, the wedges are provided with teeth or sharp threads adapted to bite into and prevent a displacement of the rebar relative to the barrel
Data Source
Figure 1
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AI summary
An anchorage device (3) and a method for connecting the device to an upstanding end of a rebar (1) after the opposite end has been embedded in concrete. The anchorage device (1) forms a head around the upstanding end of the rebar (1) that will be covered with concrete to create bearing surfaces to hold the rebar in place within the concrete. The anchorage device (1) includes a barrel (5) having a tapered bore (10) within which to receive the upstanding end of the rebar. A lid (12) extends across the top of the barrel (5), and a threaded bolt (40) is rotated through a threaded hole (38) in the lid and into contact with the upstanding end of the rebar (1) to apply an axial pushing force thereto. A segmented jaw (24) slides through the tapered bore (10) of the barrel (5) into surrounding locking engagement with the upstanding end of the rebar (1) to connect the device thereto.