Post-tension tube foundation and method of assembling same

A post-tensioned tube foundation for supporting a structure subject to high upset forces, comprising:

• an outer corrugated metal pipe (CMP) including an inner surface defining a cavity extending between a first open end and an opposite second open end, the outer CMP positioned within an excavated hole defined along a ground surface, the second open end of the outer CMP positioned adjacent to a bottom surface of the excavated hole, the first open end of the outer CMP positioned adjacent to the ground surface;
• an inner CMP including an outer surface extending between a top end and a bottom end, the inner CMP positioned within the cavity of the outer CMP such that an annular space is defined between the inner CMP and the outer CMP;
• a tubular concrete base positioned within the annular space defined between the inner CMP and the outer CMP;
• and
• a plurality of bracing beams extending radially outwardly from a top end of the tubular concrete base, wherein at least one of each of the plurality of bracing beams includes a support arm and an anchoring member, wherein the anchoring member includes a minimum thickness that is greater than a maximum thickness of the support arm.

A method of assembling a post-tensioned tube foundation for supporting a structure subject to high upset forces, comprising the steps of:

• excavating a hole including a tapered interior surface extending from a ground surface to a bottom surface of the hole;
• inserting an outer corrugated metal pipe (CMP) into the excavated hole such that a gap is defined between the outer CMP and the tapered inner surface of the excavated hole, the outer CMP including an inner surface defining a cavity extending between a first open end and an opposite second open end, the second open end of the outer CMP positioned adjacent to the bottom surface of the excavated hole, the first open end of the outer CMP positioned adjacent to the ground surface;
• filling the gap defined between the excavated hole and the outer CMP with cementitious material to form a tapered shape;
• inserting an inner CMP within the cavity of the outer CMP such that an annular space is defined between the inner CMP and the outer CMP, the inner CMP including an inner surface defining an interior cavity;
• backfilling the interior cavity with material to a top end of the inner CMP;
• positioning a plurality of tensioning elements within the annular space defined between the inner CMP and the outer CMP;
• pouring concrete into the annular space defined between the inner CMP and the outer CMP to form a tubular concrete base;
• forming a plurality of reinforced concrete bracing beams extending radially outwardly from the tubular concrete base, wherein the plurality of bracing beams are formed from concrete and unitarily formed with the tubular concrete base, wherein at least one of each of the plurality of bracing beams includes a support arm and an anchoring member, the support arm being connected to the tubular concrete base and the anchoring member extending downward from an outer end of the supporting arm, wherein at least a portion of the anchoring member is positioned below the ground surface;
• and
• tensioning the plurality of tensioning elements to cause the tubular concrete base to compact downwardly.