Northwestern Mutual, a financial services company headquartered in Milwaukee, is building a 32-story tower and 3-story glass structure within its downtown campus. The design complements Santiago Calatrava’s Quadracci Pavilion of the Milwaukee Art Museum. © Studio AMD
The first major 21st-century addition to the Milwaukee skyline will be a new tower specifically built to house financial services giant Northwestern Mutual.
February 4, 2014—Northwestern Mutual, which was founded in Janesville, Wisconsin, in 1857, relocated to Milwaukee in 1859. Since that time, the financial services giant—which currently boasts $202 billion in assets—has operated its headquarters out of a series of buildings within the city, renovating or replacing structures in its downtown campus as it has grown. Most recently, the financial services company operated from a complex of four buildings connected by skywalks and garden space with views over Lake Michigan. Now, one of these buildings—a 34-year-old, 16-story building clad in carnelian granite and designed by architect Der Scutt—is being carefully dismantled to make way for a gleaming 32-story tower and 3-story glass structure. The gently curving, prow-shaped tower that will overlook the lake is the first significant addition to the city’s skyline in this century.
“The extraordinary site provided the design team with numerous unique conditions, which generated many of the most distinctive aspects of the project,” said Nancy Clayton, AIA, LEED GA, the senior associate on the project for the architecture firm Pickard Chilton, which is based in New Haven, Connecticut. Clayton wrote in response to written questions posed by Civil Engineering online. Jon Pickard, FAIA, RIBA, is the firm’s design principal for the project.
“Northwestern Mutual’s decision to expand its campus downtown has created many opportunities to contribute to the urban character of both the streetscape and the skyline,” said Clayton. “The site’s location at the eastern edge of the city led to the creation of a large, flexible, open workspace in the tower overlooking Lake Michigan, Veteran’s Park, and the architectural masterpieces of [Eero] Saarinen’s War Memorial and Art Museum, and Santiago Calatrava’s Quadracci Pavilion.” (Read “Winged Victory,” Civil Engineering, January 2002, pages 34 to 43.)
The 435,500 sq ft glass, steel, and stone Commons building will
extend two blocks in length, and offer multiple entrance points,
including one at Cass Street. © Pickard Chilton
The shape of the tower’s floor plates—gently curving on the south side, and a more typical square shape to the north—as well as the open bays were fashioned to ensure flexibility in planning the interior office spaces, as well as to maximize employees’ views across the lake and the ability of daylight to enter the space, Clayton said.
The 700,000 sq ft tower will contain 26 office floors of approximately 26,000 sq ft each, boosting the capacity of the downtown campus from 3,000 to 4,900 employees, according to the company. The 40 by 58 ft column-free bays created by the structural system are double the typical size of many office towers, according to Brian Pavlovec, P.E., S.E., a principal of Magnusson Klemencic Associates (MKA), and the project manager for the firm’s structural design work on the project. Pavlovec also wrote in response to written questions posed by Civil Engineering online. Ron Klemencic, P.E., S.E., M.ASCE, the chairman and chief executive officer of MKA, is the principal in charge of the project for the firm.
Despite the size of the bays, Pavlovec said, “the ceiling height is higher than normal, thanks to intense coordination between the architect, mechanical, and structural engineers.” Within the tower, a concrete core that will house the elevator systems and stairways will resist wind loads. Metal decks supported by steel columns and composite steel beams will create the floor slabs.
Unusually, the entire tower will be located on a mat foundation rather than the deep foundations typically used to support tall buildings in Milwaukee, Pavlovec explained. This is because shallow foundations “are more cost-effective and well suited to accommodate the over-excavation and backfill associated with demolition of [the site’s] previous buildings,” he said.
As part of the project, a three-story “Commons” building is also being added to the campus. The 435,500 sq ft glass, steel, and stone structure will extend two blocks in length, and offer views of the lake and of an expanded three-acre garden space on the campus. The Commons will include the main entry lobby for the campus, as well as multipurpose and training spaces and such amenities as dining areas, a fitness center, a visitor and company history center, and exhibition space.
As part of the Commons, a new six-story, sky-lit atrium will be
added between the wings of the company’s historical 1914
headquarters building. Pedestrian access bridges will be added to
the exterior of the historic wings, within the new atrium, to provide
access to and from the Commons. © Studio AMD
As part of the Commons, a new six-story, skylit atrium will be added between the wings of the company’s historical 1914 headquarters building, which has been preserved. The atrium will be the heart of the new Commons. Existing escalators that currently fill up much of the courtyard that is located between the two wings of the historical building will be removed and new pedestrian access bridges will be added to the exterior of the historic structures—but within the new atrium—to provide access to and from the Commons. “Fortunately, the design team includes a Milwaukee-based structural engineering firm, ZS LLC, which has worked on existing facilities at Northwestern Mutual for several years,” Pavlovec said. This made the incorporation of the historical building into the new Commons structure easier to accomplish.
The Commons will be a braced-frame structure with metal decks, steel columns, and composite steel beams. “The eastern half of the columns and braced frames are supported by conventional spread footings, and the western half are supported by an existing basement from a tower built in 1930,” Pavlovec noted. The existing basement that the new Commons building will top did serve to complicate the design, he said, but it had to be preserved because it housed essential equipment for several existing buildings. “Though the basement was designed to support a taller building, the new loads are concentrated on relatively few existing columns, and the columns are supported by wood piles,” he said. “[So] the soils engineer tested the piles to ensure the capacity is adequate to support the new loads.”
On-site work to remove the existing building began in December, and the dismantling of the uppermost floor is anticipated to begin shortly. Each floor will be carefully gutted and then removed from the top down, so that the company’s goal of recycling 75 percent of the building’s material can be met.
Ground-breaking for the $450-million new tower and Commons is scheduled for this fall, and completion of the new campus additions is anticipated by 2017.