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Termination and Anchorage for TCB

Question
State IL
Description Text

With regards to the termination and anchorage for the F-shape temporary concrete barrier that was recently tested, the soil conditions are not representative of many field installation locations.  Our soils would typically be much weaker and require significantly longer piles or other measures to provide equal performance.  Would this require site specific design?  Or would it be feasible to design for a worst case (weak soil)?  Designing a standard application for a weak soil condition might result in over strengthening the anchorage, leading back to excessive loads?  This seems to be a practical problem for application of the design.  Could the report include a recommendation on how to address this?

 

In addition, I have some questions regarding installations where the barrier would end on a pavement.  In many cases, if we carry the barrier out to the earth beyond the pavement or shoulder we may impede contractor access to the work area.  A version of this for anchorage to a paved area would be worth more consideration.  Also, we usually require a pad for the sand barrels.  Perhaps a leave out area could be defined to accommodate the piles, with the area topped with a compacted aggregate?

Keywords
  • Temporary Barriers
Other Keywords none
Date July 9, 2009


Response
Response

The anchorage we used in this design was developed previously as part of a low tension cable anchorage. It was developed for use in general roadside fill conditions and tested in soil that meets the specifications for MASH. We believe that the anchorage will perform well given normal variations in soil conditions. We do not believe that the anchorage would need to be modified unless extreme soil conditions were present.

 

Anchoring the barrier in the paved area presents more challenges. When the anchor is loaded, energy is absorbed through deflection of the anchor in the soil. Anchoring the barrier to concrete would reduce the deflection and increase the loads for the same level of energy absorption. We do believe that this can be done, but it will require further study. As far as the size of the leave out required, I believe that is defined on the report in the recommendations section and is shown in the CAD in Figure 47.

Date September 23, 2009


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