A building under construction on the University of Colorado Anschutz Medical Campus in Aurora, Colo., features a complex geometry of steel framing and exposed structural concrete that makes it the campus’ new signature structure.
The seven-story, 394,419-sq-ft Anschutz Health Sciences Building (AHSB) features a large interior atrium, several floors of offices, clinical spaces, a data center, conference center and a wet lab. The project is being constructed by JE Dunn with Anderson Mason Dale (AMD) and ZGF Architects leading the design.
When construction is complete in fall 2021, the $242-million AHSB will host a myriad of formerly siloed departments scattered across the CU Anschutz campus. “This building is bringing together a conglomerate of research, study groups and departments that will collaborate to advance personalized medicine and genomics research, and its design is a manifestation of that collaboration,” says James Taylor, a principal at AMD, the architect-of-record.
The building was initially conceived to house the Colorado Center for Personalized Medicine, but as the needs of the campus were assessed, it grew to encompass more than that, ultimately combining multiple behavioral health programs into one facility and providing a Tier 3 data center to serve the needs of the campus for the distant future, says Mike Barden, director of facilities projects for the CU Anschutz campus. The building also will be home to the Center for Professional Excellence, which aims to simulate the clinical environment in a controlled way.
While most of the buildings on campus have a red brick masonry facade, the university envisioned something different for the AHSB. “Chancellor [Donald] Elliman didn’t want another tall, typical research building; he wanted something unique to represent the technology and innovation of the science happening inside and draw in researchers from the Rocky Mountain region and around the country—and put CU Anschutz on the map,” Taylor says.
“Given the economies at the time, we decided a full concrete building would be best, and we wanted to celebrate that structure,” he adds.
The building’s innovative design features seven floors with varying slab edge setback and overhang dimensions, creating an articulation of the envelope and allowing for roof ledges, terraces and other unique spaces. Unlike a steel building, the concrete provides full fireproofing as well.
The design architect ZGF “was adamant that the building should not have straight columns,” Taylor says. “With all of the cutting-edge research going on inside the building, straight vertical columns just wouldn’t cut it.”
“It’s quite possible to achieve complex geometry with steel framing, but with the floorplate geometry changing at each floor and cantilevers of varying lengths, a cast-in-place concrete framing system was selected to facilitate adaptation of the structure to the architectural form,” says Ben Downey, an associate with Martin/Martin Inc., the structural engineer.
Seven sets of V-shaped columns made of exposed concrete were placed as one of the building’s main architectural features and serve not only as structural support for the six stories above, but also accentuate the unusual look and feel of the building’s primary entrance. The columns stand 42 ft tall, and half of them are tapered from 4 ft at the bottom to 3 ft at the top, requiring 32 yd of concrete per set.
“The dynamic V columns create a porch and an iconic entry to the building, blurring the line between interior and exterior and reaching out and connecting with the art walk,” says Braulio Baptista, partner at ZGF.
The V-shaped columns were studied in various configurations to meet both the structural demands and the architectural vision. They were designed “not just to support six stories, but to provide something the public can see and touch when entering the building,” Downey says.
ZGF coordinated with Martin/Martin to balance the columns with the forces and loads being transferred from the structure above, Baptista says. The angles and shape of the V were “tuned” by Martin/Martin to reflect the vertical gravity load, with the column angles adjusted to minimize net lateral forces on the building. The front columns are placed at a steeper angle than the back columns due to the higher vertical loads on the back columns, which support more floor area.
Martin/Martin and JE Dunn worked closely on the concrete mix designs. The placement required some unique forming, a self-consolidating concrete mix and a lot of patience and precision to ensure a seamless, full-height placement of concrete without construction joints. It was paramount that the exposed concrete come out of the forms clean, and that entailed many mock-ups and an extensive review with concrete mix supplier Martin Marietta and the architectural team.
Bringing the Outside In
“In Colorado, we put all our glass on the west side of the building and have great views of the Front Range, and that’s the way we have dealt with most of the buildings on this campus,” says Taylor. “But we wanted to stay away from masonry and look at a more technical skin tuned and adapted for the conditions.”
The result is a unitized system of glass and aluminum. All the apertures are sized according to different data, like sun exposure and daylighting, and the panels are made specifically for solar exposure as well as the program environment inside. “There’s a lot of science going on behind the glass,” Taylor says. “So even though it’s a squattier form, it has more daylight than skinny towers.”
The atrium stretches the entire seven stories and is topped by two massive triangulated steel trusses, both around 37,000 lb, and three large skylights. The atrium’s design is based on the image of a rock canyon, with ledges, outcroppings and nooks and crannies. Walkways feature glass walls so that people can see each other—further reinforcing the collaboration going on inside the building—and an outdoor terrace on the top floor boasts floor to ceiling glass.
The massive atrium will seat up to 1,700 people, allowing for indoor commencements and other large gatherings, a first for the campus. The design team worked together to determine how best to enclose the space while meeting all challenges for life safety and smoke evacuation. The result is an undulating skylight baffle system that eliminates direct sunlight glare into all occupiable spaces within the core of the building while allowing for the maximum amount of daylight. The baffles also control the smoke layer for better smoke evacuation.
“It will be one of a kind when completed,” says Charlie Slattery, JE Dunn senior project manager. “There is only one 90-degree corner on the outside; most of the floors don’t stack, and each is a little different than the floor below it. The shape of the building constantly changes.”
With JE Dunn engaged in a construction manager-general contractor role early in the project, the team was able to work closely to push material strengths and achieve design efficiencies. For example, the concrete columns were poured with 9,000-psi concrete and utilized high-strength Grade 75 vertical reinforcing, while a more traditional approach might be to use 5,000-psi or 6,000-psi concrete with Grade 60 reinforcing. The stronger concrete and reinforcing ultimately saved money while providing for a more elegant, less bulky design.
The site was formerly a parking lot, so JE Dunn developed a plan to mill the asphalt and reuse it at the company’s laydown yard. The milled asphalt was used in place of imported gravel, and as a result, the contractor diverted 100% of the waste asphalt from the landfill. Once the project is complete, the university will have a gravel lot made from the recycled asphalt.
The dense layers of existing utilities on campus, both from CU’s build-out and remnants from the former Army base on the site, created early sitework issues; 19th Street in particular has a high density of existing and abandoned utilities, Slattery says.
In addition, the AHSB building ties into the existing RC2 building to the east at three points. Because the new building will block the air flow at the existing RC2 generator exhaust exit locations on level one, the only solution was to reroute the exhaust stacks to the eighth floor mechanical penthouse of the new building to avoid exhaust getting into the fresh air intakes on level two, Slattery says.
“All of this work had to be done while maintaining university operations, which is quite the coordination challenge,” he adds.
With the recent spike of the novel coronavirus in the Denver-metro area, keeping the crews COVID free has been a big part of the contractor’s safety focus. “Construction definitely looks different during COVID,” Slattery says.
The project has been averaging 230-250 people on site per day and will hit a peak of around 300 in the first quarter of next year. JE Dunn screens all employees every morning—a questionnaire and temperature check are required to get on site and masks and social distancing are required at all times.
“One of the bigger challenges is avoiding gatherings of people on the jobsite; lunch time is especially challenging. We have had to move meetings outside or go virtual and be extra vigilant in reminding the workers to keep their distance,” Slattery adds.
“COVID has been one of the biggest challenges thrown their way,” says Taylor, “but the JE Dunn team has managed it without any delay in quality or schedule.”