Pub. 42004-510C
234/234SBA RED ALERT
®
Tower Assemblies
Page 4 of 14
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Pier Foundation Depth and Conduit Entry
The pier should protrude a minimum of one inch above the finished grade when the surrounding area is
not concrete or asphalt. Determine the required length of concrete form tube by adding the height desired
above grade to the required 42-inch below grade pier depth.
Install conduits in the pier as needed for installation.
Conduit is not supplied by GAI-Tronics.
Consideration for power, Ethernet, telephone, 75-ohm RG6 cable, and any other customer wiring
determines the number and size of the conduit entries (see Figure 2 for typical conduit arrangements).
Figure 2. Sample conduit arrangements within tower
Concrete Form Construction
1.
Place the 24-inch diameter concrete form tube on a bed of crushed stone in the excavated hole.
2.
Place an 18-inch diameter by 38-inch long rebar reinforcement cage into the concrete form tube
before pouring the concrete.
The following materials are necessary to construct the reinforcement cage:
Four 38-inch long #4 rebar rods
Three 18-inch diameter #4 rebar stirrups
Precut wire ties
To construct the reinforcement cage:
1.
Tie a horizontal stirrup at the center of the four 38-inch rebar rods.
2.
Tie the two remaining horizontal stirrups 18 inches above and below the center point (see Figure 3).
3.
Place the cage on one-inch block spacers, centering the cage within the concrete form tube.
The top of the cage should be at least three inches below the top of the pier.
