By Steve Roloff, P.E., LEED AP
The Hamel Music Center at the University of Wisconsin-Madison is a world-class concert hall that required extreme accuracy in its design. This one-of-a kind music facility required structural and acoustic designs that would work together. Teamwork and expert knowledge resulted in just that: extraordinary sound quality and listening experiences for university students, faculty and community patrons. Many experts gave careful consideration to the facility’s structural strength and support, reverberation and sound isolation, acoustical performance and materials used, among other specifications.
A School in Need
The Mead Witter School of Music was housed within a campus building constructed in 1969. Over the years, significant building changes to keep pace with the times had not occurred, outside of a major asbestos removal in the 1990s. Staff were teaching, and students were learning in an environment that begged for physical and functional upgrades as the school continued to grow. The need for sound isolation was paramount to the musicians’ achievements of excellence.
Predevelopment for a new School of Music with a modern environment began in the mid-2000s. While the goal for building occupancy was early 2017, multiple setbacks left the project on hold until many generous donor contributions allowed the project to resume in 2014.
Beyond budgetary considerations, the new building would need to connect the campus to its surrounding community. But how would this connection be achieved? In order to create this new arts corridor, the Hamel Music Center would be situated along busy University Avenue. Next door to the Hamel Music Center stands the Chazen Museum of Art, University Theatre across the street, and the Wisconsin Union and Wisconsin Union Theater down the block and around the corner.
The team’s goal was to design a building fit for rehearsing and performing. Acoustics and sound isolation needed to be top tier for exceptional performances unlike any other. Our structural engineering team faced challenges of isolating sound stemming from busy pedestrian and vehicular traffic (including ambulances) along University Avenue, which is one of the city of Madison’s most traveled vehicular streets. Additionally, noise pollution was expected from doors opening and closing, chatter within the lobby, loud HVAC systems, and music played in adjacent halls. Each of the music center’s halls (concert, recital and rehearsal) and its lobby needed to be isolated from one another, like a vault for acoustics.
Solutions to highly unique problems were inventive, such as the use of acoustical isolation joints (AIJs) that were essential to providing superior sound isolation around the three individual halls. Acoustical isolated construction, an acoustical coffer system and other techniques were also employed.
Unique Sound Treatments
The overall structural design that worked perfectly for acoustical requirements and sound isolation was to essentially place three separate buildings within one larger building. The concert, recital and rehearsal halls are self-supporting, using independent lateral truss systems, and isolated from the large overall building (including the main lobby and its required support space) via the acoustical isolation joint.
The two-inch acoustical joint assembly may be small but its impact is critical to the structure: It essentially separates the concert hall from the rest of the building framing into, and supported by, the 16-inch concrete walls surrounding and serving as part of the hall’s structural system.
A typical joint consists of steel beams connected to a steel haunch welded to an embedded plate placed at the outside face of the hall’s concrete wall. Direct steel-to-steel contact would transmit noise and vibration in the finished building and this needed to be avoided. To create the isolated joint, a neoprene bearing pad was added on top of the steel haunch on which the in-framing steel beam sat via a steel bearing plate atop the neoprene pad. To secure this connection, a pair of threaded studs welded to the haunch bolted down the beam.
To avoid direct contact of the stud’s washer and nut to the in-framing beam, a neoprene washer was added between the beam and stud washer. But the problem was not fully resolved, as the steel-on-steel contact could still occur between the studs and the beam and its bearing plate. To further eliminate noise transfer, a neoprene bushing surrounded the weld stud. This resulted in a connection design in which no steel touched and eliminated the possibility of reverberation. (However, these connections were permitted to transfer loads.) The structural design incorporated hundreds of these joints.
Beyond this joint assembly, the concert hall’s perimeter concrete walls, soaring to a 70-foot maximum height, easily addressed lateral stability needs. The structure outside of the hall was attached to the hall’s walls via the acoustical isolation joint. This connection eliminated the need for unsightly and costly columns in the structural design. Instead, the column-free areas offer unobstructed views of concert performers.
The recital and rehearsal halls utilized double-wall construction. For the recital hall, this consisted of an exterior precast wall panel in conjunction with an interior acoustically isolated concrete masonry unit wall. Similarly, the rehearsal hall’s perimeter used a precast panel but with an acoustically isolated interior drywall system instead.
An acoustical coffer system (a series of strategically sized and strategically placed concave and partially or fully hollow circles) line the concert hall’s walls. These sizable circles treat sound by absorbing and reflecting it, along with the hidden reverberation chamber areas where sound actually passes through. The coffer system is visible and fits in beautifully with the rest of the hall’s aesthetics.
Structural Design Enhances Building Aesthetics
The Hamel Music Center’s second floor lobby hangs from the roof structure to create a column-free area at the main lobby and a floating lobby appearance, with a monumental staircase connecting the two levels. The lobby combines ductwork laterally into a curtain-wall system, disguising the necessary pipes while also incorporating them in an aesthetically pleasing way. To achieve a crack-free floor appearance, the structural design called for a 4-inch drop of the structural concrete slab floor. The floor was infilled later with a colored concrete topping slab properly jointed and separated from the structural floor.
Unique to the rehearsal hall is its view to the activity on bustling University Avenue. A corner of this hall’s double walls was cut open and, in its place, sit a double set of windows, providing musicians and pedestrians a view of the other. The design application prevents outside noise from entering the hall and allows the music to remain solely within the rehearsal space. Double cantilevers and leaning steel columns were designed to support the exterior’s zig-zag precast panels that float over this corner condition.
Both recital and rehearsal halls feature distinctive exterior wall shaping. Beyond aesthetics, these shaped precast panels are sloped in different directions and used as part of the mass required for the acoustic outside box wall system. In order to make the shapes, molds were designed exclusively for this project. A lateral truss system provides the support required for these walls, enabling them to stand freely.
A New Star on Campus
Design and construction occurred between 2014 and 2019 at a total cost of $55.8 million. And in October 2019, the Hamel Music Center celebrated its grand opening. The new recital hall’s capacity nearly doubles that of the old recital hall. The concert hall’s stage, unlike that of its predecessor, comfortably fits a large group of student-musicians.
Connection to the community happens through the Hamel Music Center. Increased social connections are a direct result of the new building. Passersby on University Avenue can catch a glimpse of students at practice in the Kaufman Rehearsal Hall. The school’s former recital hall used to host 160 performances a year, but the new Collins Recital Hall is planned to deliver more than 350 performances year after year. Community music instructors may hold lessons within the building, and occasional music guests may hold an event here. Digital streaming technology further connects the students’ music to communities throughout Wisconsin—and far beyond.
The isolation of the concert, recital and rehearsal halls from one another is completely unlike that of other auditorium and performance hall designs. Indeed, the University of Wisconsin–Madison’s School of Music Hamel Music Center is a rare project that calls for the fine art of acoustics.
Steve Roloff, P.E., LEED AP, structural group leader at raSmith, served as the project manager and senior structural engineer for the Hamel Music Center project. He has more than 35 years of structural engineering experience. raSmith is a multi-disciplinary consulting firm comprising civil engineers, structural engineers, land surveyors, development managers, landscape architects, and ecologists.