Excellence in Architecture

"The Advanced Manufacturing Center is an excellent example of seamless integration between building design, building purpose, and defining structural elements. The elevated crane bay connecting the length of the building puts the structure on display and becomes this iconic and unifying feature that reinforces the idea of bringing partners together in education, industry and community. The attention to detail carries through each structural element and exemplifies the spirit of the project." -- Jill Lavine, AIA, LEED AP, Founding Principal, FIFTEEN Architecture + Design, 2025 IDEAS² Awards Judge

An Arizona community college's new campus centerpiece incorporates key learning tools into its design, an architectural and engineering innovation only possible with a structural steel system that helped complete the project under budget.

Pima Community College in Tucson, Ariz., invested in significant campus additions in hopes of helping solve the shortage of qualified workers in local industries. The main component is the Center of Excellence for Applied Technology, a collection of academic and technical buildings offering transportation/logistics, advanced manufacturing, and infrastructure studies. It will provide formal degree and certificate programs, plus short-term training opportunities.

The Center of Excellence has two main buildings: the 43,000-sq.-ft Transportation Center Building (TCB) focusing on automotive training and the 95,000-sq.-ft Advanced Manufacturing Building (AMB). The latter is a three-story industrial learning facility with space to teach welding, machine tools, mechatronics, and CAD, among other trades. It also has a workforce development incubator, a flexible industry training lab, administrative offices, and a rooftop patio for outdoor learning and events.

The AMB promotes flex learning by providing classrooms and labs that open and connect to outdoor areas to provide extended spaces for project-based learning. This centralized circulation spine is connected visually and functionally by a 10-ton underslung bridge crane, which transverses the entire building length above the exterior walkways and connection spaces. The crane, which can transport materials throughout the facility, provides a visual cue for students to see and understand the connections between the various learning pathways.

A Clear Choice

The main structural system is comprised of composite floor deck supported by wide-flange steel beams and columns, as well as metal roof deck. Hollow structural sections (HSS) braced frames comprise the lateral load system. The crane runway beam is supported by the main building columns instead of a separate supporting structure. The structural steel system was the only choice for this unique design because of its economy, aesthetics, and flexibility.

A building this large and complex can often go above the initial construction budget. The steel structure helped ensure that the superstructure was designed as efficiently as possible so other supplementary items, such as the metal screens and façade elements, were not value-engineered out of the project. The column grid system was studied intensely during the schematic design phase to find a bay size that was wide enough to maximize the floor framing capacity but not too wide to cause too much vibration.

After finding the right bay size for the loading and massing of the building, the structural engineers worked closely with the architects to limit changes during design development. The outcome was a project built for less than $400 per sq. ft and $3 million under budget.

The learning spaces’ manufacturing focus warranted a more industrial building aesthetic, resulting in lots of exposed structural steel. The exposed structure contributed to the design aesthetic of the interior spaces, such as classrooms and lab spaces, and significantly drove the exterior design. In addition, the metal screens along the building’s south and east sides contribute to the façade design while also reducing the building’s cooling loads and providing shaded outdoor learning environments. The screens were constructed of exposed wide-flange and HSS steel framing, with a perforated metal B-deck as the screen element.

Pima Community College wanted the AMB to adapt to changes brought on by evolving student needs and allow a wide range of industry partners to lease the space. These requirements meant selecting a structural system that could be easily modified to support new hanging loads of ducts, pipework, and equipment, and be easily reinforceable if future equipment loading exceeds the current structure capacity.

Crafting the Crane

To reduce the additional cost of the crane, the building superstructure resists the gravity and lateral loads of the crane. Having the building superstructure support the crane structure allowed the building’s braced frames to support the lateral loads. However, this support plan proved to be challenging in the transverse direction. The crane structure was elevated approximately 8 ft above the surrounding roof diaphragms, and a braced frame could not be placed in the crane bay without obstructing the crane travel. The solution was to provide knee braces from the crane columns down to the roof beams below to transfer the lateral loads directly from the crane assembly to the roof diaphragm, which would then transfer the lateral forces to the superstructure’s braced frames.

The knee-brace geometry was carefully considered with input from the architect so the crane roof could still appear to be floating above the roof and provide the required lateral support. The brace was kinked so that the portion that went through the roof assembly became vertical, ensuring an easier condition for the roof contractor to install around and properly waterproof.

Additionally, the crane needed to traverse the building’s expansion joint. Introducing an expansion joint is not a typical detail in the design of a crane runway beam, so a custom connection was designed. A crane has severe limitations when sloped, so the engineering team collaborated with the crane manufacturer to handle an increased slope of 3⁄8 in. per ft. The resulting detail is a steel bent plate that covers the 5-in. gap that is fixed on one side and can slip on the other. The plate tapers from 3⁄8 in. down on either side so that the crane can move across the expansion joint while allowing the two structures on either side to move independently.

The crane has a 28-ft cantilever on both ends of its runway, allowing it to pick up equipment directly from truck beds. The cantilever’s stringent deflection requirements were difficult to achieve, especially with the required depth restrictions so that the crane could travel above the building’s parapet. The design solution was to weld a 1-in. plate top and bottom to the crane runway beam and to provide in-plane HSS bracing, which stiffened the runway beams and delivered the lateral load back to the columns.

Pondering Key Placements

The building’s length required an expansion joint to divide it into two, and the natural joint placement was at the bridge between the main volumes on either side. A double framing line at the expansion joint was implemented, providing a separation solution for the gravity system. However, the real challenge came when considering how to stabilize the floor diaphragm laterally at that same spot.

Due to the program layouts and limitations, the AMB offered few locations where braced frames could be added to support the east-west lateral loads. Furthermore, the crane runway occurred from the north to south ends of the structure, eliminating a whole bay to place a braced frame. A braced frame on the expansion joint’s north side stabilized the edge of the northern massing of the structure, but one could not go on the south side to provide stability for the bridge’s floor diaphragms.

During design, the structure was analyzed to determine if the floor structure could cantilever the 57 ft from the next brace frame located on the opposite side of the bridge. The overall movement at the north edge of the bridge structure created a need for lateral support along the expansion joint boundary. The solution was to provide a steel plate connecting the diaphragms across the expansion joint, allowing the required movement in the north-south direction but translating the lateral load from the bridge diaphragm across the joint into the braced frame line to the north. The carefully detailed custom connection provides the lateral support for the bridge floor diaphragms and the crane roof diaphragm above.

Indoor and outdoor spaces are intertwined throughout the AMB. There are multiple locations where an outdoor walkway or patio occurs over conditioned spaces below, which meant the outdoor walkway system had to act as a roof, thus requiring the continuous insulation mandated by the energy code and design lanes for proper drainage.

The drainage issues were solved by stepping the floor diaphragm 12 in. to allow for 3 in. to 6 in. of rigid insulation sloped to internal drains with 3 in. of wearable concrete slab on top. The steel structure easily allowed for the diaphragm steps to occur. The structural engineers worked closely with the architects to align the building steps at column grids for efficiency. When alignment was not possible, the steel detailing’s inherent flexibility allowed the steps to be located where needed.

Steel as an Aesthetic Staple

While the exposed structural steel and perforated steel screens enhance the overall building aesthetics, steel contributed to the architectural expression of two other primary areas: the west façade and the connection from campus to the TCB.

The west façade is the new entrance to the campus block, and architects wanted a striking design. The architects created exterior installation and finish blocks dubbed “the French fries” that alternately project and recess from the plane of the façade, creating a dynamic effect above the lower level’s concrete masonry unit exterior. Hidden behind the finish material, the French fries’ massing is cold-formed metal framing attached to HSS frames.

Constructing the entire assembly of structural steel had several advantages. Notably, having one materiality in the assembly ensured the frame construction was one subcontractor’s responsibility and facilitated quick and easy installation. Once the structural steel was erected, the metal stud fabricator provided the intermediate framing later when the exterior wall framing was installed and did not become a pinch point for the construction timeline.

The campus block to TCB connection was accomplished at the AMB by separating the building’s massing so visitors could still see the TCB from the AMB’s east side. The AMB’s two masses were connected at the second- and third floor-bridge and with the crane overhead.

On the AMB’s east side, an egress stair from the third-floor patio to the second-floor bridge became a challenge for the structural engineers. Avoiding support columns at the landing maintained the strong visual connection to the TCB under the bridge and stairs. Vibration was a major concern because the single run of stairs was long, and it was supported at the top by a cantilevered beam and at the bottom by a long-span beam. Without proper support, the assembly would have been noticeably bouncy. Two rods at the stair landing hung from the crane roof provided additional stability without visually blocking the view.

The $29 million project opened in time for the 2023–24 academic year. Pima Community College has been a staple in the Tucson area’s skilled trade education since its founding in 1969, and the AMB has positioned it to remain that way for the next 50 years and beyond.

Owner: Pima Community College, Tucson, Ariz.
General contractor: Chasse Building Team, Tucson, Ariz.
Architect/structural engineer: DLR Group, Phoenix