Precast AT&T Antennas Foundation at the Pittsburgh Zoo
The Pittsburgh Zoo had an existing wooden pole supporting AT&T’s antennas for cellular
service to the visitors and employees of the Pittsburgh Zoo located in Pittsburgh, PA. The
existing service was located behind the education building opposite the parking lot. At the
back of the education building, the ground sloped up a hill. Access to build a traditional
foundation for a new steel monopole was formidable. Working with Black and Veatch,
various options using the Cell Blocks precast foundation system were reviewed. An additional
challenge was keeping the existing antennas on the wood pole until the new monopole
was in place.
The plan view layout placed the Cell Blocks foundation in front of the existing wood pole. Using the design reactions of the proposed monopole and antenna loading, the precast foundation was indicated on the zoning drawings as 7-foot x 14-foot in plan view consisting of ﬁve blocks.
Plan View Layout
Due to limited access to the lifting equipment, the Cell Blocks system was modified to make the blocks one third the size of the typical 7’ x 7’ block. The blocks were cast as 2’-4” wide by 7’ long, therefore reducing the weight from 15,000 pounds to 5,000 pounds. The weight was similar to the handling weight of the new monopole.
The contractor installed the grounding system and prepared the level granular base foundation. In the afternoon prior to setting the foundation blocks, the crane set up in the parking lot and unloaded the pole and the blocks from the delivery truck.
Since the parking lot had to be vacated by 9 AM, the setting of the blocks commenced at 5 AM and were placed and post-tensioned in less than 90 minutes.
Taking into account the completed foundations are immediately full strength, the poles and cabinets were set immediately after the foundations were installed. Using patented post-tensioned precast concrete CELL BLOCKS for the Pittsburgh Zoo foundation made the installation extremely fast and it fit perfectly into the limited space available.
The steel monopole, antennas and other heavy lifting were complete by 8 AM and the crane was removed from the parking lot at 9:30 AM.
Using CELL BLOCKS provided for minor disturbance of the existing ground conditions, minimizing the safety concerns about unknown underground hazards and was predictable. As an added bonus, the business interruption was minimal and improved connectivity for the visitors at the Pittsburgh Zoo is assured.
Installation of Cell Blocks Foundation Blocks
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