By: Renzo Piano Building Workshop

The gateway to Columbia University’s new Manhattanville Campus at 125th Street and Broadway, the new University Forum is a highly visible and iconic multipurpose component of the new campus.

As the third building of Phase I of the new campus, The Forum complements the recently completed Jerome L. Greene Science Center and the Lenfest Center for the Arts, adding “communication” as a cornerstone of the new campus. The 5,200 square metre [56,000 square feet], three-storey Forum provides a centre for communication shared among three major programmatic elements:
- An active ground floor (“the Urban Layer”) open to the community
- A 430-seat auditorium and associated break out spaces for seminars, and
- Two storeys of academic research offices and meeting rooms, serving Columbia World Projects (CWP) and the Obama Foundation Scholars.

Consistent with the other Phase I buildings, the highly transparent and luminous ground-floor level of the three-storey building is permeable and open to the public. In addition to serving as the lobby for the auditorium above, this Urban Layer houses cafe, meeting spaces and other public functions. Along the south side, fritted glass canopies help protect pedestrians from rain and the interior spaces from direct sunlight, and also reduce the scale of the building at the pedestrian level.

The two storeys above the Urban Layer contain the auditorium and associated support spaces, foyer, meeting rooms, classrooms, and offices. A basement below grade houses other support and mechanical spaces.

Building Materials, Form and Expression 

The building program dictates the architectural vocabulary of the building’s enclosure. For example, the offices are expressed with a glazed façade since they require daylight, and the transparent ground floor is functionally open to the public. The opaque volume of the auditorium is expressed with a prefabricated concrete skin. Mechanical systems are exposed on the roof.

Following the proportions and articulations of the Neuroscience Center (glass) and Arts Center (metal panels), the precast concrete panels of The Forum share a common language with the other Phase I buildings, yet create a unique expression and identity. Their fine finish provides a subtle impression under changing conditions of natural light and weather. The precast concrete panels also provide the initial means of acoustic separation between the auditorium and the adjacent elevated subway station.

The plasticity of the concrete wraps from the vertical plane of the façade to form a soffit at the recessed Urban Layer, and the soffit expression continues into the interior with glass fibre reinforced concrete (GFRC) panels. The building looks like a ship levitating above the Urban Layer, facing directly to the Hudson River just a few blocks west. The Forum completes the architectural and material language/palette of Phase I using precast concrete panels to anchor the building.

Achieving A Flawless Exterior Finish

By Matthieu Gagné

To finalize details and reduce costs, BPDL used a Design Assist approach with the project design team which lasted several months. We had worked with the Renzo Piano Building Workshop on two previous projects (see the Whitney Museum article in the Spring, 2015 issue of Imagineering) so client expectations were high.

From a visual standpoint, the project guidelines were to ensure that the appearance of the precast concrete exterior panels would match that of the concrete poured on site. Taking a closer look at the construction details of the prefabricated concrete panels, one can notice the inserts located at the corners of the prefabricated panels which mimic the fastenings points typically found in concrete formwork. To create the illusion of on-site poured concrete, we decided to use grey-coloured concrete, the same mix as used for the Whitney Museum, and only lightly acid washed. Achieving a uniform, defect-free exterior appearance of the precast concrete panels was the main challenge of the project. Typically, the sandblasting phase allows for the removal of surface manufacturing defects. The production team ensured that the forming tables were perfectly clean to minimize the presence of surface imperfections when the forms were removed. With this approach, what you get at the plant after stripping the forming panels is what you will see upon installation.

In addition to the 169 prefabricated concrete panels which form the exterior envelope of the building, another major challenge to maintaining a uniform appearance among the concrete elements was the manufacture of the 373 prefabricated GFRC (glass fibre reinforced concrete) soffit panels which are visible from both the outside as well as the inside. The GFRC soffit panels needed to perfectly match hydraulic concrete. Since the two materials do not react equally to an acid wash, we had to modify the concrete mix pigments for the soffit panels. From an engineering standpoint, our biggest challenge was the design of a special fastening system which would allow the continuous and unobstructed installation of the prefabricated concrete soffit panels. Since their location would not give access to the backs of the panels, we used a “Unistrut” system which allows the panels to be hung similarly to a suspended ceiling.

To make this system work, we reduced the width of the panels to about one metre [3 feet], allowing the panels to be installed from one side only in a predetermined sequential order. The exterior precast concrete panels were pivoted into place at the job site during the installation. As the building structure uses a steel frame and a concrete slab on steel deck floor system, the precast concrete panels have embedded steel brackets which connect to steel fasteners welded to the steel structure.

Matthieu Gagné is an engineer and project manager at BPDL Inc.

PHOTOS: Frank Oudeman, courtesy of Columbia University, and BPDL Inc.