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We need your opinion on an issue
Nucor now has 2 types of cable
Typically these systems were
The attached .jpgs show varying
How much movement or shifting do
Thanks for any advice.
|Other Keywords||Cable anchors|
|Date||August 12, 2013|
From a brief review of the photographs and design details, several points are worth noting.
First, the diameter of the concrete shafts are approximately equal, but the TTI shaft is embedded around 20 in. more used in the New Zealand system.
Second, the TTI system has an individual anchor for each cable, while the NZ system has all cables directed into the anchor system.
Third, the NZ upward shaft movement appears to be a function of the relative distance away from the third shaft location. The third shaft location appears to be a rotation point around which shafts 2 and 1 are incrementally jacked upward and out of the hole. This upward movement or easier shaft movement may be occurring during high loading events, re-tensioning of cables after impact events, creep after consolidation of soil on inward side of anchor holes over time or during impact events which may increase gaps around concrete shaft, or combinations thereof. The load path in the NZ system may seem more conducive for lifting end concrete shaft out of the holes.
Deeper concrete shafts would likely eliminate this phenomenon in the NZ system. I would suggest raising this concern with Nucor so that they are aware of this situation and can fix it in future installations, or even existing systems where soil and environmental conditions make it easier to occur.
Our preliminary thoughts would be that replacement may be appropriate if the end shaft has raised nearly 2 in. or so. However, it may be beneficial to also pose this question to the manufacturer to get their thoughts on the potential for degraded barrier performance when shafts 1 and 2 are already jacked above grade.
|Date||August 12, 2013|
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