Re-anchoring Clamp for Live Tendon Retensioning
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Solution Overview
Problem
Existing methods for reworking post-tensioned concrete structures require breaking and removing concrete, cutting tendons, and re-anchoring, which necessitates temporary shoring to prevent structural failure due to tendon de-tensioning, a time-consuming and costly process.
Innovation Solution
A method involving the use of a re-anchoring clamp to transfer tension to the concrete structure, allowing grout to cure around the clamp before cutting tendons, thereby avoiding the need for re-shoring by maintaining tendon tension during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tendons are cut and re-anchored using conventional methods, then the concrete structure can be reworked to insert openings, but temporary shoring is required to prevent structural failure due to tendon de-tensioning
Solution Approach 1:
The re-anchoring clamp is installed on the tendon before the tendon is cut. This preliminary action allows the clamp to maintain tension on the tendon throughout the cutting and grouting process, eliminating the need for temporary shoring to support the structure during rework operations.
Solution Approach 2:
The re-anchoring clamp acts as an intermediary device between the tendon and the concrete structure. It transfers the tendon tension to the concrete through grout anchorage, allowing the tendon to remain tensioned even after cutting, thereby eliminating the need for temporary shoring support.
2Adaptability or versatility
If conventional re-anchoring methods are used requiring concrete removal and re-pouring, then new anchors can be affixed to tendons, but the process is time-consuming and requires structure shoring
Solution Approach 1:
The re-anchoring clamp is installed and the tendon is cut before the grout is poured. This preliminary action allows the grout to be poured into an existing cavity without requiring formwork or extended curing time, as the clamp maintains tension throughout the process.
Solution Approach 2:
The method extracts the tendon from the concrete structure by cutting it, while the re-anchoring clamp maintains tension. This allows the tendon to be re-routed or re-anchored at a new location without requiring the original concrete to be removed and re-poured, significantly reducing construction time.
3Productivity
If tendons are cut and re-anchored using traditional methods, then rework can be performed, but the structure must be shored to avoid failure from tendon de-tensioning
Solution Approach 1:
The re-anchoring clamp is installed on the tendon before cutting occurs. This preliminary action ensures that the tendon remains tensioned throughout the entire rework process, maintaining structural stability and eliminating the need for temporary shoring support.
Solution Approach 2:
The re-anchoring clamp serves as an intermediary that transfers tendon tension to the concrete structure through grout anchorage. This intermediary mechanism maintains structural reliability during rework operations by preventing tendon de-tensioning that would otherwise require shoring support.
Data Source
AI summary
A method for retaining tension in a stressed tendon cast in a reinforced concrete structure includes removing concrete from the structure to expose the tendon, attaching a re-anchoring clamp to the exposed tendon, the re-anchoring clamp comprising two partial sections assembled to enclose the tendon, pouring grout around the re-anchoring clamp and allowing the grout to substantially cure.