Methods for constructing tensionless concrete pier foundations and foundations constructed thereby

A method of installing a concrete pier foundation comprising:

• excavating a hole;
• placing an outer CMP into the hole and pouring slurry between the outer CMP and an inner edge of the hole;
• placing an inner CMP into the hole inwardly of the outer CMP to create an annular space between the CMPs;
• pouring a concrete plug at a bottom of an inner area surrounded by the inner CMP;
• partially backfilling the inner area above the concrete plug with soil;
• assembling a plurality of tower anchor bolts in an annular arrangement and secured to one another to form a tower anchor bolt cage;
• placing the tower anchor bolt cage within the annular space with upper ends of the bolts extending above a top of the foundation;
• pouring concrete into the annular space;
• completing backfill of the inner area with soil;
• pre-grouting an upper surface of the concrete poured into the annular space with additional concrete including high strength grout to create a level support surface for a tower base flange;
• installing a floor on top of the soil that was backfilled within the inner area;
• mounting the tower base flange on the level support surface and post-tensioning the tower anchor bolts;
• and
• post-grouting an area around the tower base flange and bordered by at least the outer CMP up to an upper edge of at least the outer CMP, the upper edge of said outer CMP being flush with a top of the foundation, the top of the foundation being defined as an upper surface of the concrete forming the foundation when the foundation is complete.

A tensionless concrete foundation for supporting a tower comprising:

• a concrete pier in an excavation, said concrete pier including an outer CMP and an inner CMP having a smaller diameter than the outer CMP to define an annular space between the inner and outer CMPs when the CMPs are placed within the excavation;
• a plurality of sleeved anchor bolts embedded in said annular space and secured at their lower ends to an embedment ring adjacent a bottom of the concrete pier, the anchor bolts extending upwardly to above a top of the foundation;
• and
• a plurality of lateral reinforcing and spacing members bolted to the inner and outer CMPs and extending horizontally across said annular space, said plurality of lateral reinforcing and spacing members providing bursting steel resistance and also allowing for CMP positioning, spacing, and location eccentricity adjustment.

A method of constructing a tensionless concrete pier foundation in an excavation, said concrete pier including an outer CMP and an inner CMP having a smaller diameter than the outer CMP to define an annular space between the inner and outer CMPs when the CMPs are placed within the excavation, the method of constructing comprising:

• placing a plurality of tower anchor bolts into the annular space;
• securing upper ends of the tower anchor bolts to a bolt alignment ring;
• lifting the tower anchor bolts out of the excavation by the bolt alignment ring and securing lower ends of the tower anchor bolts to an embedment ring to form a tower anchor bolt cage;
• lowering the tower anchor bolt cage into the annular space;
• leveling the bolt alignment ring to plumb the tower anchor bolt cage;
• pouring concrete into the annular space to fix the embedment ring and tower anchor bolts, upper ends of the anchor bolts extending upwardly to above a top of the foundation;
• and
• removing the bolt alignment ring.