Architect of Record: Skidmore, Owings & Merrill LLP (SOM), Chicago, IL
Structural Engineer of Record: Skidmore, Owings & Merrill LLP (SOM), Chicago, IL
Mechanical Engineer of Record: AEI Affiliated Engineers, Inc.
Construction Manager: Bovis Lend Lease/Clancy & Theys (joint partnership)
Total Project Cost: $110 million
Total Project Size: 210,000 sq ft
Floor System: Flat Slab
Framing System: Cast-in-place reinforced concrete frame with shear walls
Award: 2013 CRSI Award Winner – Educational Facility Category
Photography: Tom Rossiter Photography
STRUCTURAL FRAMING SYSTEM
The new University of North Carolina (UNC) Genome Sciences Building (GSB) is an eight story, 210,000 square foot structure and the centerpiece of the Bell Tower District master plan. Skidmore, Owings & Merrill LLP (SOM) lead the master planning and acted as both the architect of record and structural engineer of record. AEI Affiliated Engineers, Inc. acted as the mechanical engineer of record.
This project establishes a vital link between UNC’s historic north campus and its medical school to the south. It is a land reclamation effort, transforming a surface parking lot and back alley service area into a new science quadrangle, park, and Kenan Woods expansion.
GSB is a center for interdisciplinary research, connecting biologists, chemists, computer researchers, and the medical school to the campus intersection of academia and medicine. The building creates an intellectually stimulating environment for the transfer of ideas and knowledge. Upper floors house the research greenhouse, wet and dry laboratories, and support services.
UNIQUE DESIGN FEATURES
Structural engineering design played a critical role in the realization of many of the project objectives. The three “pod” arrangement of the building lent itself to a box-like structure, where cast-in-place (CIP) concrete walls join the flat plate slabs to form a three-story box above the second floor. In order to maximize circulation options at grade level, SOM placed two large lecture halls underground and raised the labs above the ground floor, leaving more open space and passageways at grade. Maximizing flexibility in the building’s underground lecture halls meant keeping them column free. Structurally, this was accomplished via 84 inch deep haunched concrete girders that span 63 feet and transfer out the columns coming down from the labs above. To further enhance the GSB’s open feel at the ground level, SOM framed the levels above with wide column spacing (up to 55 feet) and long cantilevers (up to 14 feet) over three sides of the building. Thick (18 inches to 19 inches) CIP reinforced concrete flat plate construction was used to meet the strict vibration requirements associated with sensitive lab equipment. SOM located the building’s office spaces on the cantilevers where vibrations are less restrictive.
The monolithic nature of the GSB’s wall-floor-roof concrete construction is dramatically exposed at the face of each of the three pods, where the bare concrete frames the building’s glazing like a shadow box. SOM enhanced the extant thermal mass of the concrete walls with embedded insulation panels at critical locations. The insulation required two layers of reinforcing on each side, as well as special boundary detailing on all four edges. Other large areas of the walls, slabs, and soffits are also architecturally exposed, allowing for a great material reduction in other finishes. In order to achieve the GSB’s desired appearance, SOM carefully designed the concrete mix with color admixtures and special aggregates. A white slag made from recycled content was used as a partial cement replacement to benefit the concrete’s color. The resultant warmth of the visible concrete juxtaposes the building’s sleek glass and wood finishes. SOM achieved a high gloss finish on the floors via multi-step polishing; special framework panels helped achieve a similar finish on the walls. 7 foot wide by 4’-4” deep concrete haunches raise the roof slab up to cantilever 27 feet beyond the supporting walls, creating the dramatic curved roof overhang at the interior corner of the building.
REASONS FOR CHOOSING REINFORCED CONCRETE
- In the Genome Science Laboratory Building (GSB), Skidmore, Owings & Merrill LLP (SOM) had to account for laboratory vibration restrictions as well as the structural stressors inherent when using architecturally exposed concrete with tie-holes and rustification joints. The underground lecture hall also required deep girders that span 63 feet in order to transfer load from the columns above.
- Self-consolidating concrete for tight pours, Grade #75 reinforcing steel (rebar) for critical columns, and plastic-coated framework in order to give the building’s walls a glossy finish.
- The GSB sits on a sloped site that has variable below-ground rock formations. The building’s architecturally exposed concrete columns, walls, slabs, and soffits also required that careful attention be paid to forming, placing, and stripping procedures.
- The GSB deploys 14 foot cantilevers and embedded insulation in the laboratory pod walls. The partial basement levels required different types of foundations and different bearing elevations.
- CIP reinforced concrete frame with shear walls.