Architect: Arrasmith Judd Rapp & Chovan Architects, Louisville, KY
Structural Engineer: Rangaswamy & Associates Inc., Louisville, KY
Construction Manager: Sullivan & Cozart, Louisville, KY
Total Project Cost: $22.5 million
Total Project Size: 200,000 sq ft (phase one)
Award: 2013 CRSI Award Winner – Commercial Building Category
Photography: Arrasmith Judd Rapp & Chovan Architects, Louisville, KY
Rangaswamy & Associates Inc., Louisville, KY
STRUCTURAL FRAMING SYSTEM
NUCLEUS is a development by the University Of Louisville Foundation (a joint venture between the City of Louisville and the University of Louisville). The first phase of the project is an eight-story, 200,000 square foot (200’ x 115’) office/dry lab building that is planned to serve as an incubator for healthcare related start-up companies. An entire city block, bounded by Market Street on the North, Jefferson Street in the South, Floyd Street on the West, and Preston Street on the East, with great visibility from Interstate I-65, adjacent to the Medical Campus of the University of Louisville is dedicated for this development.
The master plan envisions a four-building complex, comprising 900,000 square feet with a 1,500 car parking garage. The typical existing buildings along Market Street are four stories and constructed of brick load bearing walls. The architectural design called for the new buildings relate to the classical architectural themes of the historic buildings along Market Street in appearance as well as scale. Hence, the building is creatively articulated to break the vertical dimension by offsetting the top four stories from the bottom four stories. This design blends the architecture of the new building with that of the existing buildings along the Market Street and to a person viewing the top four floors feels that these four stories are images of part of a far away skyscraper. The offsets help to break the visual height of the building and integrate the new building into the existing environment.
UNIQUE DESIGN FEATURES
Due to the architectural features, the structural engineer (Rangaswamy & Associates, Inc) was certain that reinforced concrete was the most efficient method of framing for this project. The building is constructed of augercast piles, steel reinforced concrete pile caps, concrete columns, beams and wide module floor joists. The entire structural system consists of very complicated steel reinforced concrete that was designed aesthetically to blend with the surrounding environment.
The following benefits were recognized by the development team:
- Cost savings of approximately $600,000.00
- Building height reduction by keeping the entire floor system to 24-1/2″ only.
- Expensive field welded moments connections were eliminated by the substitution of concrete cantilever beams.
- Typical horizontal braces that interfers with the ductwork and other building systems were eliminated with moderate savings in Heating Ventaliation and Air Conditioning (HVAC) cost.
- The cast-in embedded plates and anchors along the fascia of concrete beams for brick support simplified the fascia brick construction.
- By providing concrete cantilever beams the fenestration at the entrance was simplified to mere vertical stud framing rather than very expensive light gage tower framing.
- Cost saving not only realized in the structural framing, the concrete framing also substantially simplified and reduced the cost of other allied trades.
REASONS FOR CHOOSING REINFORCED CONCRETE
This building is rectangular in plan with several breaks in the vertical as well as horizontal planes. Is constructed of reinforced concrete moment resisting frame designed per International Building Code 2006 and applicable State of Kentucky supplements. The foundation system consisted of augercast piles of 16″ diameter with an allowable load of 125 tons and pile caps. The floor system composed of 4-1/2″ thick slab over wide module one-way joists of 20″ deep x 6″ wide ribs spaced at 6′-0″ on centers. The wide module joists were selected for this office/laboratory building to facilitate future floor openings for additional staircases and/or other openings. To reduce the building height and utilize a straight HVAC ducting system, the joists frame was 24-1/2″ deep band beams spanning up to 45′. The floor design live loads varied between 50.0 psf to 125 psf depending on the usage.
Portions of the roof are green to reduce the stormwater runoff. Review of the structural floor plans show that on the upper four floors the exterior façade moves inward by several feet. This design was was accomplished by having cantilevered concrete beams and slabs around the entire structure for the bottom 4 floors. The use of reinforced concrete made this plan easily to achieve by simply extending the interior beam reinforcing to create the cantilever. This method was extremely cost-effective. The exterior facade also had several bump outs along each side. Using reinforced concrete made this as simple as adding some extra steel reinforcement. Since the building contains leasable office space, the owner required the greatest amount of open space possible. The concrete column design was thoroughly reviewed through several iterations of varying reinforcing sizes and quantities and concrete strengths to provide the most efficient construction while also using the smallest column size possible.