|Logged in as: Public User|
We have a contractor request to substitute an anchor bolt
See the attached PPCMB Anchor Plan.pdf, the detail is
This anchor would be used in leu of the 3/4" drop in
Please take a look at the anchor properties and let us know
Please find the attached submittal package for our Screw
Our contractor has the project and is looking for a more
|Other Keywords||Tie Down|
|Date||May 1, 2017|
|Attachment||PPCMB Anchor Plan.pdf|
We looked at alternative anchors for the steel strap tie-down in some previous research for KDOT. I have attached a letter report that details that work.
During that work, we looked at several mechanical anchor alternatives like the one you sent. We found that those anchors compared well to the drop-in style anchors in terms of tensile capacity, but tended to have trouble developing the required shear loads. The difference in shear capacity was largely attributed to the larger diameter of the sleeve used for the drop-in and the higher grade steel used for the drop-in bolt.
Two potential mechanical anchor alternatives were identified.
1. Red Head Large Diameter Tapcon (LDT) 0.75-in. diameter x 4.5-in. long
2. Simpson Titen HD 0.75-in. diameter x 5.0-in. long
In the case of the Screw-Bolt+, we would need to ensure that the anchor could match a tensile capacity of 18.7 kips and a shear capacity of 25.6 kips that was found for the drop-in anchor used in the original crash testing of the system. We have used the approach that any replacement anchor must meet or exceed the capacity of the tested anchors in order to ensure similar performance. The shear capacities of the Screw-Bolt+ anchor are currently limited to 24.3 kips, so it would fall just beneath the tested anchorage. This anchor is very similar to the Wedge Bolt anchor used by Powers Fasteners, which did not meet the shear load criteria in the KDOT work. Thus, we could not recommend it at this time.
However, either of the alternative anchorages noted in the attached study are acceptable.
Let me know if you have any further questions.
|Date||May 2, 2017|
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
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