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The images in more detail
Washington, D.C is located next to the Potomac River on the east coast of the United States, nestled between the states of Maryland and Virginia. The cityscape is characterised by imposing buildings, impressive monuments and famous museums. One example thereof is the John F. Kennedy Center for the Performing Arts, known as the Kennedy Center for short, which catches the eye primarily due to its architecturally pleasing design.
The three pavilions of the building extension were constructed along the south side of the existing structure on a plot covering around 4.6 ha. The open studios span numerous exterior and interior spaces, providing space for rehearsals, performances, and works of art. They are characterised by their distinctive, clear-cut lines and ergonomic, sweeping curves, dovetailing perfectly with the striking cityscape. White in-situ concrete and various chequerboard patterns complete the overall look of the extensions.
Architectural highlight in the Skylight Pavilion
The Skylight Pavilion is the largest of the three structures and, with its 12.9 m high ceilings and wave-shaped wall, making it one of the highlights of the project. The wall has a continuous curvature that runs both vertically and horizontally. As such, every free-form box supplied by PERI needed to be custom-designed. In practice, this necessitated the development of a 3D model that could create a virtual depiction of the wall, thus paving the way for the development of project-specific PERI special formwork. The panels were manufactured at the nearby PERI site in Elkridge, Maryland, allowing delivery to the construction site on schedule.
Load transfer challenges
It quickly became apparent during the precursory test phase that the fresh concrete pressure would be comparatively high at around 100 kN/m², bringing with it high reaction forces for the two stop-end systems on each side of the Upper Glissando Wall. This resulted in a stripping force of over 120 kN and a horizontal force of over 420 kN in the uppermost concreting section. Since the two forces were working in opposite directions, they did not cancel each other out due to the differently positioned points of application but led to a twisting of the stop-end. These significant demands called for a far stronger stop-end system than what is typically required in a standard case. The solution: Heavy-duty standard products from PERI, such as the RCS Rails, were used. In this way, a torsionally stiff yet cost-optimised system could be used, which was held in position by anchors in the ground.
At 45 m of twisting, the extreme length of the concreting section resulted in a high horizontal force. For this, the PERI engineers developed a project-specific solution in which standard systems were tested and coordinated perfectly with special-purpose solutions. Ultimately, this special-purpose solution made it possible to safely transfer the high forces acting on the moulding boxes.
To this end, a tension-compression system (TCS) designed by PERI engineers was used to connect the panels horizontally so that the load could be gradually transferred to a supporting structure system instead of to the adjacent panels. This prevented the panels from being overloaded. The overall objective of the TCS was to transfer the horizontal loads from the moulding boxes to the stop system (TCS), which functioned like a chain. This was the only way to use standard components and the standardised PERI moulding boxes for the extremely high forces that occur.
PERI standard systems in action
In addition to the technically sophisticated special-purpose solutions, numerous tried and tested PERI standard solutions were also used. For example, the single-curve walls of the three pavilions were formed with RUNDFLEX Circular Wall Formwork, which was delivered flat and whose radius was able to be adjusted on-site with ease. The formwork for the high, straight walls was realised using the VARIO GT 24 Girder Wall Formwork, which with-stands high levels of pressure and was thus optimally equipped for the challenges of the project.
For the slab formation process, the flexibly applicable MULTIFLEX Girder Slab Formwork was the preferred choice throughout the entire project as it allowed the architectural concrete surfaces to be formed to the quality standards expected. In addition, SKYDECK Panelised Slab Formwork was used for the slabs of the underground car park. SKYDECK’s lightweight system components allowed the construction site team to conserve energy during the construction process. The majority of the bracing was assembled with components from the VARIOKIT Engineering Construction Kit.
Winner of the ACI Overall Excellence Award
On October 26, 2020, this unique project won the American Concrete Institute’s ACI Overall Excellence Award. The Kennedy Center was first honoured in the "Low-Rise Buildings" category and then selected as the overall winner from the winners in all categories. These awards are presented by the ACI board on an annual basis on the recommendation of the Awards Committee. The awards honour outstanding achievements in concrete construction the world over – especially in terms of combining creative techniques with innovative technologies. The non-for-profit ACI Foundation was established in 1989 to promote progress, innovation, and cooperation.