Scientific Growth of a Campus

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Wesleyan University, a private liberal arts university in Middletown, CT, began reimagining its science complex more than a decade ago. The New Science Building, scheduled for completion in 2026, will be a signature building for the campus. Working with PAYETTE architects, the Simpson Gumpertz & Heger Inc. (SGH) engineering team designed the structure, taking care to stay true to the campus focus and mix of historic and modern structures. Part of the larger-scale campus plan involves removing Hall-Atwater, located adjacent to the New Science Center, and renovating Shanklin Hall, a 1920s building.

The New Science Building supports the growth of Wesleyan University's science programs and is a focal point on campus with its sweeping glass and stone facades. It stands out amongst the many quintessential New England brick-clad buildings and brownstone facades that dot the campus. The science building incorporates research and support rooms, teaching labs, classrooms, a vivarium, and advanced instrumentation. This programming creates structural design challenges, including differential lateral earth pressures, long-span spaces, transfers, geometric considerations, and vibration performance.

The New Science Building is comprised of steel framing and slab-on-metal-deck composite diaphragms, with steel concentric braced frames as the lateral-load-resisting system (LLRS). The building has four stories plus a mechanical penthouse located at the roof level.

The site includes a substantial grade change of approximately 31 feet, allowing for slabs-on-grade at four different levels, with parts of Level 1 and Level 2 on grade in the west and northwest of the building. On top of the grade change, the building incorporates a mechanical trench space that extends 11 feet below the lowest level. The change in grade across the site results in significant differential lateral earth pressures. Transferring the differential pressure through the diaphragm to the LLRS was not practical due to the large floor openings within the load path. Ultimately, the earth pressure was accommodated by designing cantilevered retaining walls to resist it. This design also allowed for backfilling the site earlier than if the walls were designed to span between levels.

In many locations, mat foundations are used to incorporate the foundation wall footing and the adjacent isolated footings. This allows for simplicity of formwork and rebar detailing. The allowable bearing pressure varies based on elevation and location in the site. The foundation design incorporated these aspects to optimize the designs wherever possible.

A key architectural feature of the building is the atrium, which incorporates large, irregularly shaped openings that vary at each level. The atrium aligns with a series of four light monitors in the roof that drive natural light into the core of the building. The maximum atrium length is 140 feet east-west and 82 feet north-south. There are no columns within this area, which presented a series of design challenges to accommodate the unique and varying geometry of the openings, as well as steel depth restrictions along the opening edges and floor finishes that required recesses in the top of the slab-on-metal-deck. The irregular geometric openings range in size from up to 41 feet at the floor levels to 51 feet at roof level. The deepest floor recess includes wood flooring and radiant heating, which only allows for a 4-inch (total depth) slab-on-metal deck, that negatively affects vibration performance over these long spans.

Ultimately, the project team developed a unique framing plan for each level, incorporating cantilever framing around the openings to offset the deeper members from the edge and tapering beam ends to keep a low profile of the framing adding a lighter feel to the space. Cantilever framing supports long-span beams in multiple locations. The team studied to understand the combined deflections, considering the cantilever ends and the long-span beam deflection.

Laying out the beams required careful coordination with PAYETTE to ensure that all the structural steel was concealed within the varying depths of the soffits and ceiling. The irregular geometry and framing also resulted in increased coordination with pipes and ductwork throughout the area. The project benefited from this early coordination with the MEP engineers (van Zelm Engineers) and the general contractor (FIP Construction). At the roof level the framing layout in the atrium also must account for four light monitors with varying geometry to drive natural light into the atrium space. These allow an abundance of natural light to flow through all the floor openings below.

Along the west edge of the building is a double-skin glass curtain wall system. To minimize the visibility of the structure along this edge, SGH designed exposed built-up plate columns aligned with the curtain wall mullions. These columns incorporate three built-up 50 ksi plates. The two outer plates are 8 inches x 2-1/2 inches and the inner plate is 6 inches x 2 inches to allow for a staggered fillet weld to connect the plates. The 7 inches total width blends nicely behind the curtain wall mullions. The wall itself is supported by cantilevers at Level 3, which are tapered W36 members decreasing to about 28 inches at the edge of the building.

The New Science Building features three sets of monumental stairs. Two of these stairs span between the atrium openings from Level 2 to Level 3 and Level 3 to Level 4. As previously mentioned, the atrium opening framing includes many cantilevers and long spans, which in turn support these stairs at the top and bottom. The floor framing increases the flexibility of the support framing of the stair assemblies; therefore the stair structure requires additional stiffness to offset this additional stiffness and still to meet the stair vibration criteria of AISC Design Guide 11. Per Design Guide 11, the vertical natural frequency of the stairs is greater than 5 Hz and the horizontal natural frequency is greater than 2.5 Hz. Additionally, the stair stringers have depth restrictions since they are an architectural feature. To meet the depth restriction, the designs incorporate three parallel HSS10x8 stringers to achieve the required stiffness. The stairs also have 1/2-inch-thick fascia plates along the outer edges to conceal the stringers and treads. These plates contribute to the stiffness of the stairs but are not part of the structural design.

The building includes a large auditorium between Level 1 and Level 2. This requires a 72-foot clear span to accommodate the openness of the auditorium. This meant transferring out six columns from the upper levels. In the space above the auditorium, one column line aligned with an architectural wall, so a built-up, story-deep truss was designed to create the open space below. The truss consists of wide flange shapes for the chord and web members. The layout of the web members is asymmetric to align the top joints with the column transfers above. The joints were designed and fabricated as nodes with bolted connections to simplify erection. On the other two column lines, there is no wall above, so the transfer was made through built-up box girders. The ceiling had a depth restriction, so two W40x431 beams were designed to act compositely with a 1-1/2-inch-thick continuous plate welded to the top and bottom flanges.
The architectural layout did not allow for braced frames in the northwest area of the building. This is in part because the auditorium is located in this zone. Therefore, the story-deep truss ends up delivering lateral load from the diaphragm due to its relative stiffness. This needed to be accounted for in the lateral analysis of the building. SGH analyzed the system holistically in two ways; one including the truss as a lateral element and one without it. That allowed us to isolate the truss and its connections and properly design for the lateral load they inherently receive, while the LLRS was designed assuming there is no contribution from the truss, so the braced frames are designed for the full lateral load on the building.

Many areas in the New Science Building are lab spaces and require a specific vibration performance of 2,000 mips (micro-inches per second). Due to the changes in the column layout from level to level, some column transfers occur in lab spaces. The column transfers result in large beams that help stiffen the floor and help the vibration performance. The vibration performance was studied using both the ETABS building analysis and standalone spreadsheets developed following AISC Design Guide 11 procedures. The lab spaces are large, with beam spans up to 31 feet-2 inches and girder spans up to 18 feet. To meet the vibration requirements, beam sizes range from W18 to W24, and girder sizes range from W21 to W24. Another factor used to help the vibration performance is a 7-1/2-inch total depth slab-on-deck assembly.

The exterior design of the building emphasizes crisp, modern detailing paired with a grounded, weighty stone mass—paying homage to the rich legacy of stone architecture found throughout the campus. Between the heavy stone objects, light and floating glazed elements define the welcoming common spaces. A central feature of the design is the articulation of deeply recessed windows within the stone façades, each framed by large custom fluted sill stones that suggest substantial wall thickness. SGH’s team engineered and coordinated bespoke anchoring systems and intricately shaped stones, achieving the visual heft of solid masonry while minimizing the actual volume and weight of stone used.

The New Science Building is a signature building on the campus, joining the historic nature of the surrounding campus with a state-of-the-art science complex. While many of the structural features are concealed, the intricacy of the framing is fitting for such a facility. ■