Krause Gateway Center
TYLin provided structural engineering services for the new Kum & Go corporate headquarters in Des Moines, Iowa.
This new corporate headquarters building provides a modern and highly collaborative work environment with flexibility for growth. The conceptual motif of the steel-framed building is its set of four vast planes, which emphasize lightness and transparency and are augmented by outdoor terraces and glass on all sides. Occupants enjoy column-free workspaces and an abundance of natural light that offers stunning views to the surrounding streetscape and park.
The building’s second floor is set back from its facade on three sides, creating the double height lobby. The third floor dwarfs and shades the levels below it; the fourth level extends beyond the third. The fifth and largest level is rotated about 16 degrees clockwise from the building’s western face. The sixth floor follows the axis of the fifth and includes a small pop-up for the elevator over-run and roof access.
The building’s long interior spans, exaggerated cantilevers, and thin floor plates necessitated a careful, integrated structural design process. The lateral framing for the building is a hybrid of moment frames, braced frames, and cable-tied super columns. The double height space between the first and third floors creates 32-foot-tall moment frames, complicating an already inherently flexible lateral load resisting system.
The moment and braced frame system was not enough to meet code-stipulated seismic drift criteria and project-desired wind drift criteria, so the design team used cable ties at the exterior 62-foot-tall super columns to help control drift.
Project Highlights:
- The showpiece of the Krause Gateway Center is its perimeter exterior cantilevered framing, unofficially known by the design and construction team as the “nosing”. The extreme cantilevers produced significant deflections and torsion at the outrigger end point, which was mitigated by kinking the outriggers up at their support point.
- With energy efficient features such as a green roof and generous roof overhangs, the building has earned LEED Gold certification.
Image credit: Nic Lehoux.