Since the pavilions have large openings and cantilevered corners, the structural walls are heavily reinforced and detailed to act as deep beams. The southern curtain wall of the Welcome Pavilion rests on a “swoop” slab, the vault curvature formed by blending two straight horizontal lines on different axes. The outer edge of the vaulted slab is supported by a 92-foot post-tensioned concrete beam. The vault curvature becomes more vertical as it extends east, which supports the beam through deep beam action. One of the Skylight Pavilion’s concave walls measures over 43 feet tall and twists in plane, creating a large overhang and a large base projection.
Designed by Edward Durell Stone and completed in 1971, the existing John F. Kennedy Center for the Performing Arts (JFKCPA) is both a landmark cultural facility and a living memorial. The South Plaza Expansion adds much-needed interior space with three partially buried white concrete pavilions and a two-story subgrade structure that connects them. Outside, the project includes landscaped terraces and a pedestrian bridge that spans Rock Creek Parkway.
Throughout the project, Silman used the inherent strength and flexibility of cast-in-place concrete to fuse creative structural solutions with material expression, creating a series of unique and thoughtful new spaces for education, rehearsal, and events. The site’s three pavilions – the River Pavilion, the Skylight Pavilion and the Welcome Pavilion – are all constructed out of board-formed concrete walls.
To accommodate the large formwork pressures and reactions created by the geometry of the curved walls, Silman worked closely with the formwork engineer to ensure a successful placement of concrete. Strategic construction sequencing was critical to ensure that adequate shear walls were in place to resist the temporary formwork forces.
Photo credit: Richard Barnes / JBSA.
Welcome Pavilion under construction.
- Photo credit: Richard Barnes / JBSA.
- Welcome Pavilion under construction.
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Since the pavilions have large openings and cantilevered corners, the structural walls are heavily reinforced and detailed to act as deep beams. The southern curtain wall of the Welcome Pavilion rests on a “swoop” slab, the vault curvature formed by blending two straight horizontal lines on different axes. The outer edge of the vaulted slab is supported by a 92-foot post-tensioned concrete beam. The vault curvature becomes more vertical as it extends east, which supports the beam through deep beam action. One of the Skylight Pavilion’s concave walls measures over 43 feet tall and twists in plane, creating a large overhang and a large base projection.
The design of performance spaces created a need for large column-free areas, with some clear spans measuring over 65 feet. Architectural constraints included minimizing total structural assembly depth and limiting the use of drop beams to create a uniform soffit from below. To limit concrete weight, Silman employed a voided concrete slab, combined with post-tensioning in several locations to achieve the desired spans.
Photo credit: Richard Barnes / JBSA.
- Photo credit: Richard Barnes / JBSA.
Read Caption
The voided slab method was so successful in solving long-span issues that it was subsequently applied to most of the horizontal concrete elements on the project, even in areas with more typical spans. Much of this horizontal structure is required to support a fully landscaped garden and plaza with thick soil beds, a publicly accessible lawn, and a reflecting pool.
The voided slab method was so successful in solving long-span issues that it was subsequently applied to most of the horizontal concrete elements on the project, even in areas with more typical spans. Much of this horizontal structure is required to support a fully landscaped garden and plaza with thick soil beds, a publicly accessible lawn, and a reflecting pool.
Overall, the use of void formers yielded an approximately 15% reduction of the slab dead loads and 10% reduction in seismic mass, resulting in a significant cost-savings and lessened environmental impact.
Double-height, partially-buried lobby area inside the Welcome Pavilion.
Custom formwork “crinkles” the concrete that lines several of the performance spaces, dampening unwanted echoes with the building structure.
- Double-height, partially-buried lobby area inside the Welcome Pavilion.
- Custom formwork “crinkles” the concrete that lines several of the performance spaces, dampening unwanted echoes with the building structure.
