Twist Lock Joint for Concrete-Filled Steel Tubular Structures
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Solution Overview
Problem
Existing joint systems for concrete-filled steel tubular structures (CFST) are inefficient in facilitating the connection of steel segments during the construction phase, as they often require welding or bolting before concrete pouring, which can be time-consuming and may not provide a secure, rotation-resistant connection.
Innovation Solution
A twist lock joint system using a tubular connector with projections and teeth for a tongue and groove connection, where a mechanical device temporarily locks the connector in place until the concrete hardens, ensuring a secure and rotation-resistant connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional welding or bolting methods are used to join steel segments before concrete pouring, then the connection can be made, but the process becomes time-consuming and complex
Solution Approach 1:
The joint system is divided into separate functional components: a connector element with tongue and groove features, a twist lock mechanism, and a mechanical locking device. This segmentation allows each component to perform its specific function independently, simplifying the overall assembly process while maintaining connection strength.
Solution Approach 2:
The connector is pre-assembled with the steel segments before concrete pouring, with the twist lock mechanism already in place to prevent rotation. This preliminary preparation eliminates the need for complex welding or bolting operations during the concrete pouring phase, significantly speeding up construction.
2Ease of operation
If the connector is allowed to rotate freely during installation, then it can be positioned easily, but the connection becomes unstable and rotation-resistant
Solution Approach 1:
The connector transitions from a dynamic state (allowing rotation during installation) to a static state (locked in position after concrete pouring). The twist lock mechanism enables the connector to be rotated freely during assembly, then locked in place once the concrete sets, providing both ease of positioning and connection stability at different stages.
Solution Approach 2:
The mechanical locking device acts as an intermediary between the connector and the steel segments. It temporarily prevents rotation during installation, then allows the concrete to harden and permanently lock the connector in place, mediating between the need for easy positioning and connection stability.
3Productivity
If steel segments are connected before concrete pouring, then the structure can be assembled faster, but the connection may not be secure enough
Solution Approach 1:
The concrete itself serves as the final locking mechanism. Once the concrete is poured and hardens, it permanently secures the connector in place, eliminating the need for additional welding or bolting operations. The system uses the concrete's own setting process to provide the final security of the connection.
Solution Approach 2:
The joint system combines different materials with complementary properties: the connector provides mechanical connection features, the twist lock provides rotational restraint, and the concrete provides permanent locking and structural strength. This composite approach leverages the advantages of each material to achieve both fast assembly and secure connection.
Data Source
AI summary
Joint for concrete-filled steel tubular structures, of the type that joins two axially-aligned tubular steel segments (1). It comprises a tubular connector (2) between both steel segments (1), in a tongue and groove connection with each steel segment (1). The connector is locked against rotation by the concrete (10) filling. The male part of each tongue and groove connection comprises a circular wall (3) where at least two projections (4) are placed, the projections (4) being evenly distributed around the outside of the circular wall (3). The female part has a shell (5), the inside of the shell carrying at least two teeth (6) that define a circular hole (7) for the insertion of the circular wall (3); so the projections (4) fit between and behind the teeth (6).