Grange Insurance Headquarters, Parking Garage, & Pedestrian Bridge

Located in the historic Brewery District in Columbus, Ohio, the project consists of a 10-story addition to the existing 12-story office building, a two-story data center, and a new 1,000-space parking garage. The new office building and data center are steel-framed structures, and the parking garage is post-tensioned cast-in-place concrete.

There were several design challenges on this complex project. The new office tower and data center needed to blend in with and enhance the existing tower's appearance and address the Brewery District's urban aesthetic. The office layouts of the new tower needed to merge seamlessly with the existing office floors. This dictated a large 35-foot by 35-foot bay size for an office building with an under-floor air distribution system. This required a 1-foot deep raised floor system, and the new floors had to align with the floors of the existing office building. These factors resulted in a less-than-optimum depth for the floor framing system, which consists of a lightweight concrete slab on a composite metal deck on high-strength structural steel framing. The girders were fabricated with large web openings between the infill beams to facilitate air distribution. The total construction cost of the office addition was $90 million.

The new parking garage rises six stories with a partial basement level and provides needed parking for the expanded office building. The structure is cast in place, post-tensioned concrete. The garage design incorporates brick and glass curtain walls to match the adjacent office buildings. The total construction cost for the parking garage is $20 million.

Crossing Sycamore Street in the heart of the Brewery District in downtown Columbus, Ohio, a steel-framed pedestrian bridge connects the existing Grange Insurance office building on the third floor to a new, six-story reinforced concrete parking garage. The connector facilitates the increased flow of Grange customers and staff across Sycamore Street without interrupting the current traffic pattern below. The bridge, spanning 54 feet across the street, is designed to have a more angular look and features a single central wall intended to be visible from street level. The wall is used to showcase local artwork. Because of the angular look and the visibility requirements, the bridge is framed with a single-story-deep truss instead of the more traditional pair of parallel trusses. One of the challenges that SMBH overcame was designing a single stable truss with cantilevering floor and roof beams, despite a tendency to twist due to the unconventional floor plan. Other challenges were coordinating mechanical and electrical requirements with the need for a low profile and coordinating the bridge foundations with existing street-level underground utilities and the existing building's basement. The total construction cost for the pedestrian bridge is $1 million.