Alternative Support Systems for Cantilever - National Transportation ...

One immediate benefit associated with this configuration is that the annular plate and
anchor bolt connection has been removed. Another benefit over the embedded steel pipe and
plate option is that this embedded concrete option removes corrosion of the embedded pipe as a
potential problem. As with the previous option, the bolted connection bearing on the monopole
may require an increase in thickness for the monopole, leading to additional expense.
A potentially difficult piece to construct would be the embedded concrete pipe with bolts.
One option would be to order spun concrete poles from a manufacturer. The poles would include
prestressed strands as well as spiral reinforcement and would be light and durable. The through
bolt holes would be included by using a cast-in-place PVC pipe during fabrication. Another
option would be to use a geometric section without bolts instead of the round section with bolts.
The geometric section would provide the required torsional resistance once embedded in the
foundation that the bolts are providing in the round section.
following:
Design strength considerations for this connection include, but are not limited to, the
• Bolt shear strength
• Bolt bearing strength (on steel monopole)
• Bolt bearing strength (on embedded concrete section)
• Fatigue (of bolts)
• Breakout strength (of embedded section on concrete foundation)
• Torsional strength
• Flexural strength
As with the previous option, the embedded steel pipe and plate option, this configuration
may provide a suitable alternative to the current annular base plate and anchor bolt connection.
As mentioned before, the FDOT currently uses a detail similar to this in Index No. 11860 in their
Design Standards. Given that, the detail in the Design Standards has only been specified for use
with aluminum single column posts for ground signs.
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