Collapsible Element Pocket Former for Post-Tensioned Concrete Access
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Solution Overview
Problem
Conventional methods for forming pockets in post-tensioned prestressed concrete members face challenges in preventing concrete from filling the space between the stressing-end anchor and the concrete form, making it difficult to access the tendon after concrete hardening, and ensuring effective protection against corrosion and fire.
Innovation Solution
A pocket former with a collapsible element that extends radially outward from the pocket former body, allowing the tension member to be inserted and the concrete to be poured around it, with the collapsible element collapsing inward upon removal to create a cavity, facilitating access and protection by filling the space with grout or concrete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional pocket former is used to prevent concrete from filling the space between the anchor and form, then access to the tendon is enabled, but the pocket former cannot be reused and requires disposal after single use
Solution Approach 1:
The pocket former incorporates collapsible elements that can transition between expanded and collapsed states. During concrete placement, the collapsible elements are in an expanded configuration to prevent concrete from filling the space between the anchor and form. After concrete hardening, the collapsible elements can be collapsed to compress the pocket former body, enabling easy removal and reuse of the device.
2Shape
If the pocket former body is made rigid to maintain shape during concrete pouring, then proper cavity formation is ensured, but the device cannot be collapsed for removal and reuse
Solution Approach 1:
The pocket former body is divided into multiple collapsible elements that can independently deform. Each collapsible element includes structural components that maintain the overall shape during concrete pouring, yet can be compressed together to reduce the overall volume of the device for easy removal from the hardened concrete.
Solution Approach 2:
The collapsible elements are configured to nest within each other when collapsed. The pocket former body includes an outer shell and inner components that can be compressed together, with the inner components fitting within the outer shell during the collapsed state, enabling compact storage and reuse.
3Reliability
If the collapsible elements extend radially outward to effectively block concrete, then cavity formation is improved, but the device complexity increases
Solution Approach 1:
The collapsible elements are constructed using flexible materials that can extend radially outward to effectively block concrete during pouring, then collapse inward for removal. The flexible shell structure provides the necessary blocking effectiveness while maintaining the ability to collapse, avoiding the need for complex rigid mechanical components.
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 easy access to the tension member after concrete hardening, provides effective corrosion and fire protection by filling the cavity with grout or concrete, and ensures the pocket former can be reused by collapsing elements that return to their original position.
Implementation Method 1
The pocket former also includes a collapsible element, the collapsible element flexibly coupled to the inner portion and the outer portion of the pocket former body.
Implementation Method 2
The pocket former also includes a collapsible element, the collapsible element pivotably coupled to the pocket former body.
Data Source
AI summary
A pocket former may include a pocket former body, the pocket former body having an outer surface. The pocket former may further include a collapsible element, the collapsible element formed on the outer surface of the pocket former body. The collapsible element may extend radially outwardly from the pocket former body.