Historic structure gets a retrofit

November 8, 2017

A more than 100-year-old building needed structural renovation and upgrade to meet requirements for seismic resistance, anti-terrorism/force protection (AT/FP) and progressive collapse to serve as new office space for the 131st Civil Engineering Squadron. A steel endoskeleton provided the means to meet these requirements while preserving this resource’s historic character.

New Bones: Giving a Historic Structure a Seismic Retrofit

The 131st Bomb Wing (BW) of the Missouri Air National Guard (ANG) faced a challenge in the spring of 2011. A tornado struck the Base at Lambert Field and destroyed or damaged many buildings, which expedited plans for a future relocation. A split of the unit between Whiteman Air Force Base in western Missouri and Jefferson Barracks Air National Guard Station, on the south side of St. Louis along the banks of the Mississippi River, presented the most viable opportunity for expedient relocation.

Jefferson Barracks was first established in 1826 as a military post for operations west of the Mississippi River, and remains active today, supporting both the Missouri Air and Army National Guard. The installation was recognized for its historic significance by being listed in the National Register of Historic Places in 1972. An initial study by Mead & Hunt assessed multiple building options at Jefferson Barracks for the relocation, with Building 29 ultimately selected as the preferred location for the 131st Civil Engineering Squadron.

Diagnosing the Problem

Numerous challenges affected design requirements. The many repairs needed alone to upgrade a building more than 100 years old presented a significant amount of work. On top of the repairs, the design firm Mead & Hunt would have to incorporate seismic, anti-terrorism/force protection (AT/FP), and progressive collapse design requirements to comply with current building codes and Department of Defense regulations. At the same time, renovation designs needed to preserve the historic character of the building.

Building 29 was originally one of three cavalry barracks completed in 1898 and is a contributing resource to the Jefferson Barracks Historic District. The brick building has a three-story center core with two-story flanking wings. Once vacated after World War II, the building was only used for unheated storage. The overall lack of adequate structural support and reinforcement needed to be brought up to current code. A limestone foundation supported unreinforced limestone block basement walls.  The walls of the upper floors consisted of three wythes of unreinforced brick. Wood joist floor construction spanned from the brick walls to a rough sawn 8 x 10 beam line in the wings spanning between cast iron columns. Interior stud walls supported floors in the center section of the building. In collaboration with the Missouri SHPO, the decision was made that historic features such as the exterior materials of the building and original interior cast iron columns would be retained in the renovation.

Design for seismic resistance was necessary due to Jefferson Barracks’ location near the New Madrid seismic zone. While the zone extends from northeast Arkansas to the southern tip of Illinois, effects from earthquakes extend to St. Louis and beyond.

AT/FP standards also needed to be met, including those for progressive collapse. The proximity of existing roads to the building, unreinforced brick bearing walls, and structural support for arched window openings all contributed to the challenges in AT/FP compliance.

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