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mounting beam guard on top of box culvert

Question
State WI
Description Text

We have a contractor that wishes to use  3/4" x 6.25" carbon steel wedge anchors verses epoxy anchors for the  details MwRSF developed in TRP-03-114-02 and TRP-03-278-13.

Contactor indicates the following in their submittal

Arbor Green would like to use a mechanical wedge
anchor for the mounting of guardrail posts to the top of box culvert between
the WB Beltline ramps and Broadway St.  Specifically,
we would like to use a 3/4"x 6.25" carbon steel wedge anchor.  The data sheet I have provided shows pullout
strengths well in excess of the plan notes per bolt, and there will be 4 bolts
in each plate.










Keywords
  • Guardrail
Other Keywords culverts
Date July 28, 2016
Attachment Wedge Anchor Data Sheet.pdf
Attachment detail.docx


Response
Response The attached detail showed an anchorage that was dynamic component tested in report TRP-03-278-13. It consisted of 1" dia. A307 bolts anchored into a minimum of 4,000 psi concrete to a depth of 8" using an epoxy with a minimum bond strength. The dynamic testing found that this configuration was capable of developing the moment capacity of the post and was acceptable for use with the previously crash tested culvert mounted guardrail system. 

The original anchorage consisted of 1" dia. A307 bolts that were through bolted into the top of the culvert. In order to be conservative and in lieu of dynamic testing, we have required that any alternative anchor must meet the ultimate capacity of the as-tested design. For the 1" dia. A307 bolts, that would correspond to an ultimate tensile load of 36.4 kips. 

The proposed TruBolt wedge anchors do not appear to have sufficient capacity. 3/4"dia. TruBolt wedge anchors have a maximum capacity of 17.7 kips at the length/embedment noted above in 4,000 psi concrete. Even the largest diameter TruBolt wedge anchors only develop 26.5 kips in 4,000 psi concrete. Thus, we are unable to recommend the alternative anchor at this time. 

It may be possible that the TruBolt anchor could function acceptably, but some form of dynamic component testing would be needed to verify the performance similar to report TRP-03-278-13.
Date July 28, 2016
Attachment trubolt.pdf


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