The Yards Pedestrian Bridge

At the center of the redevelopment known as The Yards at Southeast Federal Center, this new 200-foot pedestrian bridge spans the site of Washington’s first canal and provides an elevated walkway along the Anacostia River. The bridge’s dramatic curvature creates a feeling of compression and release for visitors passing through its circular rings. The tied-arch structure features built-up steel box chords with an arch depth of eight feet.

The arches cant inward such that the bridge deck, 18 feet wide at the abutments, tapers to about ten feet at the mid-point. The canted arches are braced by rings of varying radii that give the bridge its delicate hourglass form.

The greatest structural design challenge was balancing the flow of forces through the structure while maintaining the aesthetic-driven form. While the primary structural elements are the pair of canted tied arches, the ribs use Vierendeel behavior to provide lateral stability, forming a hybrid structure much like a covered timber bridge.

As the ribs were stiffened to resist forces transverse to the arches and to ensure the top chord’s stability, the ribs attracted more moment in the plane of the arch. TYLin engineers designed rib stiffeners that provided a sculptural solution to connections along with strength and stability.

Image credit: MPFP.