A New Landmark Building

In a city that greets the world with renowned grace and style, the new Hotel, Condominium and Museum tower presents an exciting chapter in the use of precast in leading-edge high-rise construction. Precast was selected for this landmark addition to the cityscape for its ultimate architectural design flexibility and its cost-effective constructability. The building is a civic expression of architectural bravura, incorporating a stunning convergence of world-class architecture and precast engineering.

Site

Located in the heart of the City’s most exciting and revitalized neighborhood, the Hotel and Condominium tower is next door to the Museum of Modern Art, and across the street from the Downtown Gardens and Center for the Arts. The tower itself will host a new Museum of the African Diaspora. It is situated near the city’s financial district, close to downtown shopping, and an array of fine dining establishments and nightlife.

The highly visible site was the last remaining property to be offered for development by the municipal Redevelopment Agency for the cultural center renaissance of this area of the city.

Program

The mixed-use tower comprises 42 stories above-grade. The first 20 floors are for the hotel, the 21st floor houses the mechanical systems, and the upper 21 floors feature luxury residences and additional mechanical spaces. There are four below-grade parking levels. All together, the structure supports 775,650 total square feet of usable space.

Challenges

The urban parcel represented an unconventional, and therefore challenging, shape for a number of reasons. First, an existing 1907 building occupies the northwest corner of the site, which called for an innovative strategy for providing a prominent and gracious entry for the project. Second, because the neighborhood’s street grid is rotated 38 degrees from the adjacent older city grid, the view corridor generates a diagonal axis through the tower site. Finally, because of the tower’s location in a Seismic Zone 4, the precast concrete sections had to be designed to accommodate large elastic and inelastic drift movements.

Design Intent

The carefully articulated massing of the structure responds to the scale of the adjacent buildings, while the tapestry of the highly articulated, multi-textured, and multi-colored precast skin creates a rich surface character that constantly changes throughout the day in the bright sunlight of this region of the city.

Design Solution

The tower is set back to allow the lower elements of the project to respond to the heights and scale of adjacent buildings; this scaled geometry opens up views back to the city from between tall buildings. The overall form of the tower uses the different materials of the architectural precast concrete and glass cladding to modulate views to and from the tower in response to the rotated city grid view corridors, as well as the opportunities for open views toward the nearby bay and coastal hills from the southern portions of the tower.

The presence of the historic building on the most prominent urban corner of the site presents the opportunity to arrange entry and exit on the quieter side street. This approach to pedestrian and vehicular access enriches the space between the project and the adjacent Museum of Modern Art, creating an intimate indoor-outdoor entry.

A Tapestry In Precast Panels

The design of the tower’s façade was guided by the idea of creating two distinctly textured layers to figuratively clothe the building. On the tower’s corners, tall vertical glass shafts run from the crown to the building’s base and form an inner ‘silken’ layer—giving the building the appearance of being wrapped first in a delicate transparent cloth. Outside this initial ‘silken’ glass layer, the architect and precaster worked together to weave a richly textured ‘cloak’ layer using precast. To achieve this, the team developed a rich four-tone patterned weave using horizontal and vertical reveal elements with distinct separate finishes within and across punched window panels to create a textile-like surface for the whole façade.

To articulate the cloth weave in precast, the architect chose two colors and two textures to create four distinctive elements. These elements express the tapestry as a series of interlocking, interwoven bands. The elements comprise projected horizontal sills, recessed horizontal spandrel-like elements, narrow, alternating recessed/projected vertical mullions, and flat vertical pilasters. Amazingly, each of these elements—including each of the four finishes—is contained in each precast panel.

There are three vertical ‘threads’. Two are cast with a single lighter colored concrete and finished with two different textures (one lightly sandblasted, the other more heavily sandblasted) imparting two different finishes. The third thread is a darker colored concrete with a light sandblast. Two horizontal ‘threads’ comprise one band of the heavier textured light colored concrete (base) and a second band of header spandrels-like elements are cast with a darker colored concrete and likewise finished with the heavier sandblast. The glazed ‘silken’ layer beneath the precast weave is recessed as deeply as possible within the panel, resulting in a complex façade of unusual depth and variety of shadow.

Summary

The new 42-story mixed-use structure now graces the city’s urban landscape and brings to the community new critically-needed housing, a new hotel for the city’s many visitors, and a new cultural museum – one of a number of such institutions that comprise this city’s growing fine arts neighborhood.

The project’s design intent was fully expressed by the application of precast – utilizing multiple colors and textures and planes within the same panel to convey the unique woven cloth pattern of the program’s cloak theme.

A precast skin was a fitting material for this structure which is now the tallest reinforced concrete structure in a Seismic Zone 4 within the United States.