Armed with numerous strategic alliances and the publication of many design and construction standards and guides, cold-formed steel continues to be well-positioned for tremendous growth. The building community has became more aware of cold-formed steel’s capabilities which has led to new and challenging uses for the material once limited to partition and curtain walls. Today, load-bearing applications for cold-formed steel are being used across the country for exciting projects in the hospitality, retail, assisted living, multi-family and mid-rise markets.
It is hardly surprising that in a down economy, developers are implementing strategies to maximize their return on investment all while producing award winning projects. In some cases, in densely populated urban areas especially, the only way to go is up-and that is just where the developers of multi-purpose, mixed-use projects have gone to fulfill their goals.
Once described as “hell with the lid lifted,” Pittsburgh continues to undergo a rebirth of its central core with visionary projects. Combining the tried-and-true building stock of the past with revitalized transformation, these projects offer all the amenities of a major city but with a down-home feel. One such project that has led the charge is Piatt Place, the site of a former four-story department store with three stories of underground parking which has been converted into what some have referred to as an urban oasis. Owned by Millcraft Industries Inc., this project has been a major force in Pittsburgh’s revitalization that has contributed to putting downtown Pittsburgh on the map as the location for urban living. This new seven-story mixed-use structure combines 50,000 square feet of retail space, 180,000 square feet of office space and 65 high-end condominiums.
And as valiant strides are being made to focus more attention on sustainability efforts through the reuse of existing building infrastructure, developers have also become extremely creative. Project owners Jack and Lucas Piatt, the principals of Millcraft wanted to build up on the roof by adding three new stories on the top of the existing building for upscale living spaces to offer spectacular views of the city. In addition to balconies, the condos also boast a central courtyard area to give occupants the outside experience high above the hustle and bustle of the city streets below. With design services of Strada LLC, architecture and urban design group, the owner’s dream started to become a reality.
Like any project, Piatt Place had its share of challenges, namely how to add three additional stories for residential use to the existing structure with minimal cost and disruption to the existing structure, coupled with a very tight footprint surrounded by the existing workings of a major downtown landscape without enlarging the footings. Enlarging the footings would have increased costs, lengthened the schedule, and disrupted the operations of the existing building to the point of making the project unfeasible. Conventional framing methods using structural steel and concrete proved too heavy.
Best Choice Framing
With attributes of high strength-to-weight ratio, cold-formed steel was the natural choice. Long-term durability and flexibility in design afforded the owners the opportunity to produce these high-end condominiums at prices acceptable to the market, providing the project managers with a first-class addition to urban life in Pittsburgh.According to Chad Wheatley, Director of Construction for Millcraft, “The duration to install the three-story structure atop the new steel platform was four-and-a-half months. Cycle time savings was realized in the exterior envelope also being substantially completed during this same time-frame as the cold-formed steel framing system was panelized off-site. This off-site panelization by Wyatt Incorporated of Pittsburgh included the attachment of exterior board and water barrier and allowed the building to be substantially ‘dried in’ upon completion of the $2.7 million cold-formed steel frame installation.”
To accomplish this, Millcraft hired the expertise of Turner Construction Company as the general contractor of the development. The Structural Engineer of Record was Atlantic Engineering Services in Pittsburgh, with specialty engineering for the cold-formed steel portion completed by Shaffer, Wilson, Sarver & Gray, P.C, of Reston, Va.
Work Around the Roof
The residential portion of the project incorporated a structural steel frame fabricated by Engineered Products Inc. with a composite metal deck to create a platform over the existing roof. This platform was necessary to support three stories of residential condominiums built around a beautiful central courtyard on top of the existing building. The additional residential stories were constructed atop the concrete slab using cold-formed steel and a lightweight gypsum-concrete topping.The addition was designed using cold-formed steel to serve as the primary axial load-bearing and lateral load-resisting system on the new floors. According to Ted Welti, P.E., division manager of Cold-Formed Steel for SWSG, PC, “The use of cold-formed steel, a light-weight material, allowed us to minimize the additional weight on the foundation and footing so the existing structural framing could be used and upgraded to meet building code requirements for the extra loads with minimal additional costs, making the project economically feasible.” Architectural requirements to make this an outstanding project required open floor layouts with continuous glass exterior walls to open the condo units to the exterior views of the city. As a result, no significant lengths of solid walls were available in the exterior walls for conventional diaphragm or x-braced shear walls. To overcome this framing challenge, the cold-formed steel joists and decks of the floors and roof were designed to act as a diaphragm to transfer the lateral loads from the corners and exterior walls of the building to an inner core of beefed-up and overlapped patented x-braced shear walls supplied by The Steel Network out of Raleigh, N.C. The floor and roof members were 14-inch deep, 30-foot long Joist Rite open-web joists provided by MarinoWare Steel Framing Products and Accessories.
The wide expanses of exterior glass walls, made possible and economical by the innovative use of cold-formed steel framing, have catapulted the project to success. The end result: An outstanding example of urban living contained in a structure boasting many attractive amenities-shopping, offices, fitness and beauty services-supported by a wonderful revitalized downtown have indeed made it the place to live in downtown Pittsburgh.
For additional information on this project and how cold-formed steel framing can be used to increase a project’s return on investment in other multi-family, mid-rise and hospitality load-bearing applications nationwide, contact mrizzuto@steelframing.org and visit www.steelframing.org for other valuable information including design standards, how-to guides, and solutions for your next project using cold-formed steel framing.
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