Salt lake city Public Safety Building. Case Study CS 2. Grounded in strength.

Transcription

1 Salt lake city Public Safety Building CS 2 Case Study Grounded in strength.

2 Forterra Structural & Specialty Products High-Efficiency Design, Precast Envelope System Put Dramatic Public Safety Building on Target Project Description The new Salt Lake City Public Safety Building is a remarkable structure that ranks at the top in virtually every measure that defines a high performance building. It s aesthetically exciting, sustainable, extremely energy efficient, and built to be resilient. Designed to be visually appealing and accessible to the public, the structure is on target to achieve at least a LEED Silver, and likely a LEED Platinum, rating and will be the first public safety building in the nation to approach a Net Zero Building status. It is also designed to be blast resistant and to withstand a 7.5 magnitude earthquake. A major contributing factor in achieving each of these design goals was the use of insulated precast concrete wall panels from Forterra that are load bearing and inlaid with terra cotta. Not scheduled to open until the summer of 2013, the four-story public safety building consists of 172,000 ft 2 of office, meeting and dispatch areas above ground and two levels with 143,000 ft 2 of secure, below grade parking, plus armory and evidence storage. The building will house Salt Lake City s police and fire facilities, central dispatch, an emergency operations center, and state-of-the-art media/communication facilities. A striking, integrated blend of materials Featuring a sweeping glass façade, the building curves around a landscaped public entry plaza and festival space. The concave glass curtain-wall leans back as it rises, canting one way and then another and sloping from one wing to the other. To one side, upper floors are gradually pushed back, stepladder fashion, with the revealed portion of each floor topped with a green roof. The plaza includes gathering areas, seating, sculptures, a water feature, prismatic light show, solar-powered electric outlets for electronic devices, and a memorial to fallen officers. A large, flowing solar canopy extends over the entrance and much of the plaza and is topped with integrated photovoltaic panels. Highlighting this dramatic design are terra cotta-faced exterior precast concrete wall panels. The insulated panels act as architectural spandrels and the terra cotta finish provides an old world look to the design that is currently popular in the architetural community. The terra cotta was fabricated in Europe, Portugal and Germany, and shipped to the Forterra plant in forterrabp.com

3 Project Type: Public safety building Project Owner: Salt Lake City Corp., Salt Lake City, Utah Management: MOCA Systems, Salt Lake City, Utah Architects: GSBS Architects, Salt Lake City, Utah; MWL Architects and Planners (McClaren, Wilson & Lawrie Inc.), Phoenix, Ariz. General Contractor/ Construction Mngmt.: Okland Construction, Salt Lake City Civil Engineer: Stanley Consultants, Salt Lake City Structural Engineer: Dunn Associates Inc., Salt Lake City Electrical Engineer: Spectrum Engineers, Salt Lake City Mechanical Engineer: Colvin Engineering Associates Inc., SLC Precaster: Forterra Structural & Specialty Products, Mountain Region, Salt Lake City, Utah Facility Precast Components: Insulated wall panels and architectural caps Completion: Summer 2013 Salt Lake City to be inlaid into the precast panels, according to Roger Arnell, business development manager for Forterra Structural & Specialty Products. The typical terra cotta piece was one foot wide and five feet long. The standard method of installing terra cotta would have required setting those pieces one at a time off a scaffold. Encapsulating the material into precast wall panels provided numerous advantages, says Arnell. We could cast multiple pieces, 60 to 70, into each precast wall panel, he explains. This reduced on-site erection time immensely. It also eliminated the need for scaffolding and on-site trades. In addition, because we were working in a controlled environment in our plant, the terra cotta joints are much straighter. Our production method allowed us to place and keep each terra cotta piece in exactly the right location. The result was a much higher aesthetic value in the finished design. A host of sustainable, energy-saving features Another major goal of the building design, according to project manager Chad Jones of MOCA Systems, was to achieve net zero energy emissions through the use of high efficiency building materials and systems, photovoltaic and solar thermal arrays, and energy management building operations strategies. The insulated precast wall panels consist of 1 3/16 in. terra cotta, 3 1/16 in. concrete wythe, 2 ½ in. rigid polyisocyanurate insulation, and a 4 in. concrete exterior wythe, providing an R-value of 19. Composite pin connectors are used to tie together the two concrete wythes to minimize thermal bridging. Recycled rebar is used for reinforcement and a precast architectural cap is set at the top level of the building. Solar panels also reduce building energy requirements Some 30,000 ft 2 of solar panels on the building roof and on the ground-floor canopy will provide 440,000 KWH/year from 314 KW of direct current (DC) produced. In addition, 1,850,000 KWH/year will be generated from 1,300 KW of DC produced at an on-site solar farm, according to Jones. Two diesel generators serve as back-ups.

4 Two major goals of the public safety design were to provide net-zero energy efficiency and blast resistant security. The precast wall panels fit these goals perfectly. Mechanical systems include high-efficient radiant heating/cooling tubes in the floors and solar water heating equipment on the roof. Supplementing the radiant tubes is a highly efficient, chilled beam convection HVAC system in the ceilings. Other energy saving features include energy-efficient appliances in break rooms, regenerative-drive elevators, and sophisticated monitors and controls. As a result, the project is expected to generate the same amount of energy that its uses on an annual basis. The project s numerous sustainable features include on-site rain gardens, saving of on-site mature trees, several green roof areas, vegetated open space with drought resistant plants, and seasonally-adjusted irrigation controls. The design capitalizes on daylighting with window louvers to direct sunlight. Designers also specified the use of high-efficiency lighting with automatic controls, low-voc emitting materials, reflective roofing materials, low-flow plumbing fixtures, locally-produced materials and materials with high recycled content. It s projected that materials used in the project will contain a minimum of 30% recycled content and that at least 85% of construction waste will have been diverted from the landfill. All precast components were locally produced. Water use reduction is projected to be 38%. Safe, secure and resilient In addition, as an emergency operations center, the structure had to be designed to be fully operational after an earthquake. To handle seismic events, the steel frame building is braced with 55 viscous seismic dampers, stacked on vertical columns starting at grade level. These are attached to the steel framing with special fittings. Steel moment frames are used in the parking garage. Foundation consists of 3-ft-thick concrete slab. The 9 ft by nearly 30 ft (29 11 ¼ in.) precast wall panels are connected column to column. The connections that tie the spandrel panels to the steel structure are designed to allow the precast panels to move with the columns in a seismic event. forterrabp.com

5 The structure is also designed to be blast resistant, prevent progressive collapse and ensure structural integrity. Set back 50 feet from the street and featuring step-back terraces on one side, the design offers protection against vehicular explosive devices. Manufactured with 5,000 psi concrete, the precast concrete wall panels can withstand a ballistic impact and meet Antiterrorism/Force Protection (AT/FP) requirements. Utilizing precast concrete provided an all-in-one envelope system that includes an exterior surface with a terra cotta finish, continuous insulation, and the interior surface in a single component that offers impact resistance and high thermal mass. The precast panels combine the R-value of rigid insulation with the U-value of the concrete mass, says Arnell. I m not sure it could have been accomplished with any other system /CS2/Spectrum/7.16/R