Cast-In-Place Anchor Jaw Lock for Seismic Load Stability
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Solution Overview
Problem
Conventional cast-in-place anchor assemblies experience axial movement and dynamic impacts during seismic events, leading to compromised connections between the jaws and anchor members due to axial play, which can result in separation, fatigue, and loss of hold.
Innovation Solution
A jaw lock mechanism with an axially expandable member that expands to prevent upward movement of the jaws relative to the anchor housing, combined with a separator to ensure proper jaw separation during anchor member insertion, enhancing the stability and engagement of the anchor assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spring is used to bias the jaws upward during anchor member insertion, then the jaws gain axial positioning flexibility and compliance, but the jaws experience axial play that compromises the connection under dynamic loads
Solution Approach 1:
The jaw assembly transitions from a static fixed position to a dynamic adjustable position. During insertion, the spring allows the jaws to move axially to accommodate variations in anchor member length and positioning. After insertion, the jaws are locked in place, providing stability. This dynamic behavior resolves the contradiction between needing flexibility during operation and stability during load-bearing.
Solution Approach 2:
The spring pre-biases the jaws into an engaged position with the anchor member before any load is applied. This preliminary engagement ensures that the jaws are already positioned correctly and compliantly aligned with the anchor member, facilitating easy insertion while maintaining connection integrity under subsequent dynamic loads.
2Ease of operation
If the jaws are allowed to move axially within the anchor housing, then the insertion process is facilitated with compliance flexibility, but the jaws can be forced into impact engagement during seismic events, causing separation, fatigue, and loss of hold
Solution Approach 1:
The jaw assembly is designed to be dynamic during insertion but static during load-bearing. The spring enables axial movement during insertion to accommodate positioning variations, while the locking mechanism prevents axial movement during seismic events, eliminating impact engagement and associated damage risks.
Solution Approach 2:
The spring acts as a cushioning element that absorbs positioning variations during insertion, preventing direct impact between the jaws and anchor member. This preliminary cushioning protects the connection from shock and impact forces that could cause separation or fatigue.
3Reliability
If a washer and nut are used on the threaded rod to transfer load directly to the metal decking, then the load path is simplified and jaw movement is prevented, but the complexity of the anchor assembly increases with additional components
Solution Approach 1:
The washing and nut components are extracted from the anchor assembly and replaced by an integrated locking mechanism built into the jaw assembly itself. The jaws are locked directly to the anchor housing, eliminating the need for separate fastening components while maintaining load transfer stability and preventing jaw movement during seismic events.
Solution Approach 2:
The load transfer function and jaw positioning function are merged into a single integrated locking mechanism. The jaws are directly locked to the anchor housing, combining the functions of load transfer and movement prevention that were previously achieved by separate washer and nut components, thereby reducing overall assembly complexity.
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 jaw lock mechanism immobilizes the jaws relative to the anchor housing, preventing dynamic impacts and ensuring a secure connection between the anchor member and the concrete, thereby enhancing the durability and reliability of the anchor assembly under load and vibratory conditions.
Implementation Method 1
Conventional split nut jaw assemblies will often employ a spring above the jaws and downwardly biasing the jaws. The spring also allows the jaws to be urged at least slightly upward during insertion of the anchor member.
Implementation Method 2
The jaw lock may include an axially expandable member which has a first smaller radius and is capable of flexible expansion to a second larger radius. The expandable member may be radially compressed, reducing the general diameter of the expandable member, to reduce the general diameter of the jaw lock such that the jaw lock can be received within the anchor housing.
Data Source
AI summary
An anchor assembly is disclosed for suspending objects to a concrete structure. The assembly includes an anchor housing having a jaw assembly therein and a opening for receiving an anchor member such as a threaded rod. The jaw assembly includes threaded rods having a threaded opening, a wood form anchor assembly and a metal decking anchor assembly. The wood form and the metal decking anchor assemblies may accommodate the anchor housing and the anchor housing is used in one of the wood form anchor assembly and the metal decking anchor assembly. The metal decking anchor assembly includes a nose-piece and the anchor housing is selectively connectable to the nose-piece via a locking connection such as a bayonet connection.