Concrete pier foundation with lateral shear reinforcing loops and methods of constructing the same
A concrete pier foundation having a plurality of sleeved tower anchor bolts embedded therein and a spiral loop encasement providing lateral shear reinforcement is provided. The spiral loop encasement surrounds at least a lower portion of the concrete pier and is formed by hoop steel wrapped around the perimeter of the tower anchor bolt cage. In proper soils or rock the spiral loop encasement can eliminate the need for corrugated metal pipes, reducing the cost and complexity of construction.
1. A method of installing a laterally reinforced concrete pier foundation comprising:
excavating a hole;
assembling a tower anchor bolt cage having an outer perimeter including a plurality of sleeved anchor bolts in an annular arrangement, said sleeved anchor bolts each have a lower end and an upper end, and secured at their lower ends, said lower ends being adjacent a bottom of the laterally reinforced concrete pier foundation with the upper ends of the sleeved anchor bolts extending above a top of the laterally reinforced concrete pier foundation when the tower anchor bolt cage is placed within the hole; and
wrapping the outer perimeter of the tower anchor bolt cage with, and individually securing the sleeved anchor bolts to, a spiral loop steel addition having opposing ends over at least a lower end thereof to produce a wrapped tower anchor bolt cage and provide lateral shear reinforcement to the laterally reinforced concrete pier foundation;
positioning the wrapped tower anchor bolt cage within the hole; and
securing the wrapped tower anchor bolt cage with concrete after said wrapped tower anchor bolt cage is positioned within the hole with the lower ends of the sleeved anchor bolts at the bottom of the laterally reinforced concrete pier foundation, wherein the opposing ends are embedded in the concrete;
wherein the step of excavating the hole includes digging an annular trench with undisturbed native soil forming a center area encircled by said trench, the wrapped tower anchor bolt cage being lowered into said trench and said step of securing including filling the trench with cementitious material.