Project Overview
Precast concrete architectural panels proved an essential component for achieving the aesthetic goals for Target Field, which serves as home to Major League Baseball’s Minnesota Twins in Minneapolis. The urban location and surrounding light-rail and commuter-train services added appeal, but they also created site restrictions that the precast concrete helped to overcome.
There was nothing square, straight, or plumb about the 88-ft-tall (27 m) exterior precast concrete wall system, which features large, cast-in limestone blocks. These blocks consisted of honed and quarry-creek rocked-faced stone in various thicknesses. Casting odd-sized blocks with non-uniform surfaces and thicknesses (varied up to 2 in.) and presented major manufacturing challenges.
Precast Solution
To achieve the desired look, the limestone blocks were placed face down into the forms with ¾ in. (19 mm) joints. Stainless steel ties anchored the blocks to the precast concrete wall. A bond breaker prevented concrete from entering the joints and allows thermal expansion of the dissimilar materials. The design also includes a gradation in stone color from darker at the base to lighter at the top.
The superstructure consisted of a multilevel waffle-slab floor system with concrete columns. Walls are battered a variety of degrees, while corners seem to intersect at different angles. To achieve this look, the precaster had to mark foundations, project the walls, and determine the corner conditions so panels could be fabricated to meet the as-built site conditions.
The precaster provided a tube-based, steel-frame subwall assembly to support the precast concrete well system. The limestone-faced precast concrete components were set from inside the bowl because there was no perimeter access. |