Proj Overview

Project Overview

Occupying the space where a 100-year-old steel manufacturing plant once stood, the Steel District is a modern, high-performance mixed-used office building in Sioux Falls, S. Dak. Although the building is named the Steel District, steel is not its primary structural support system. Instead, the developer, building owner, and architect chose a design concept that pairs structural precast concrete with innovative applications of ultra-high-performance concrete (UHPC). This decision was made in part because of the volatility of steel prices and the scarcity of steel materials. Using precast concrete on the project—including for the building facade and the adjacent parking structure—resulted in cost savings and interior design flexibility, offering the developer an ideal structural solution.

Nothing Like It

The Steel District is the first Class A office building in the United States to leverage UHPC to eliminate the use of interior columns and allow for complete design customization. To bring the concept to life, project precast concrete producer Gage Brothers of Sioux Falls, S. Dak., commissioned an engineering firm to compare a UHPC beam system to the original steel design. The designer team determined that a 70-ft-long UHPC beam could replace two 36-ft-long steel beam spans while also eliminating the need for the vertical columns that would be required in structural steel or traditional precast concrete designs. “By using ultra-high performance concrete, we were able to provide a column-free space without reducing head room,” said Joe Bunkers, president at Gage Brothers. “This allows for a more flexible floor plate while simultaneously reducing the amount of concrete needed.”

For the building’s users, the results are stunning. All nine stories of the building feature expansive windows that provide ample natural light along with impressive views of downtown and the nearby Big Sioux River. Floors 3 through 9 house business offices with expansive open-floor plans. The second floor features a skywalk and shared amenity spaces, and the ground level includes three restaurants. Of the project’s 2908 precast concrete elements, 86 are UHPC beams that support the entire 175,000-ft2 structure. The remaining precast concrete components include hollow core, gray panels, traditional precast concrete beams, columns, and wall panels. Thanks to the open space afforded by the structural precast concrete system, the building can be easily adapted to best suit nearly any type of future tenant, as the floor plate can be stripped down to a clean slate and repurposed depending on the need.

Gage Brothers overcame several challenges during the project. The developer wished to maintain a high vertical clearance in the occupied space, so the precast concrete producer had to develop a way to run the mechanical, plumbing, and HVAC systems through the beams. To solve this issue, the team created boxed-out sections or holes in the beams for passage of utilities. Additionally, Gage Brothers focused on producing a beam shape using the least amount of UHPC materials while resisting the combinations of shear, torsion, and flexure create by the 24-ft tributary area. After numerous trials, the team decided on an optimized box shape that reduced weight by 57% when compared with a conventional concrete solution. Because the Gage Brothers team had not previously worked extensively with UHPC, additional effort was required to develop best practices for handling, mixing, and placing the concrete as the work progressed. Gage Brothers and the rest of the project team worked through these issues to deliver an innovative precast solution that not only benefits the building’s owner and developer, but the tenants and surrounding community as well.

“This project added much needed Class A office space to Sioux Falls,” Bunkers said. “Along with the attached, all-precast-concrete parking ramp, the Steel District bookends the north end of downtown Sioux Falls and has spurred additional development in the area, including restaurants and parks.”

Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013.


2024 PCI Design AwardsSpecials Award: Harry H. Edwards Industry Advancement Award
Project Team

Owner and General Contractor:

Lloyd Companies, Sioux Falls, S. D.

PCI-Certified Precast Concrete Producer:

Gage Brothers, Sioux Falls, S. D.


Koch Hazard Architects, Sioux Falls, S. D.

Precast Concrete Specialty Engineer and Engineer of Record:

e.Construct, USA LLC, Omaha, Neb.

PCI-Certified Erector:

Gil Haugan Construction, Sioux Falls, S. D.

Project Cost:

$28.9 million ($9.08 million for the precast concrete)

Project Size:

65,000 ft² (exterior) and 153,000 ft² (structural)

Key Project Attributes

  • The Steel District replaces a 100-year-old steel manufacturing plant with a modern, mixed-use building on the north end of downtown Sioux Falls, S. Dak.
  • The nine-story, 175,000-ft² building was constructed without the use of interior columns, freeing up space on each floor plate and allowing for future readaptation of each floor to suit tenant needs.
  • Alongside the project, significant additional development, including restaurants and parks, has taken place in the surrounding area.

Project/Precast Scope

  • Nearly 3000 precast concrete components were installed on the project, including ultra-high-performance concrete beams, hollow core, gray panels, traditional precast concrete beams, columns, and wall panels.
  • The use of precast UHPC beams instead of two 36-ft-long steel beams eliminated the need for vertical columns, which would have been required in structural steel or traditional precast concrete designs.
  • Overall, 65,000 ft² of exterior precast concrete and 153,000 ft² structural precast concrete were installed.