Newly Constructed Glass and Steel Dome Earns its Place in Hollywood

By Ellen Rogers

Every year, the Academy Awards pay tribute to the greatest artistic and technical achievements in the film industry. Also worthy of such recognition is the newly completed Academy Museum of Motion Pictures (Academy Museum), located in Los Angeles. It was designed by famed Italian architect Renzo Piano, founder of Renzo Piano Building Workshop (RPBW). The gem of the project is the steel and glass dome that tops the Sphere Building, home to the 1,000-seat David Geffen Theater. The museum’s exterior construction was predominantly completed in late 2019, though it is not scheduled to open until 2021. It is devoted to the art and science of movies and moviemaking. The museum earned LEED Gold Certification in October 2020.

The 300,000-square-foot campus at Wilshire and Fairfax features a major renovation and expansion to the 1939 May Company Building, since renamed the Saban Building. It was connected to the new 45,000-square-foot glass and concrete Sphere Building, which, in addition to the David Geffen Theater, also covers the Dolby Family Terrace, which provides views of the Hollywood Hills. In addition to RPBW’s work as the design architect, Gensler served as the executive architect and MATT Construction was the general contractor (GC). Josef Gartner, a division of Permasteelisa North America Corp., installed the steel and glass dome, and Knippers Helbig was the façade consultant and structural engineer of the steel and glass structure and special features.

Glazing Showcase

Architectural glazing projects continue to become more complex, and the Academy Museum was no exception. It was also a learning experience for Rob Sanders, project manager with Josef Gartner, who was new to the glazing industry when the work began.

“Before Gartner I was on the GC side, and this was my first job as a specialty sub. I literally had never done major glass work,” he says. “That said, I embraced the idea and understood the complexity of this project, because anyone in this industry knows this is complex. I spent a lot of time with our German engineers learning about the systems and our capabilities and all of the points where we had major risk and had to mitigate that risk.”

Sanders says his team was responsible for the glass and steel dome, as well as three glass and steel bridges connecting the Saban Building to the theatre.

“We were onsite in August 2017 for the embed phase and then permanently in May 2018 until completion,” says Sanders, explaining that the glass dome is located on top of a concrete building, which houses the theatres.

Daniel Hammerman, senior project architect with RPBW in New York, says together with Knippers Helbig Advanced Engineering as structural and façade engineer of the dome, his firm fully developed construction documents together. Gartner was the successful bidder of the glazing package, explains Hammerman.

He continues, “Installation of the lightweight grid shell structure necessitated incremental tensioning of bracing cables in a careful sequence, alignment of components and constant surveying. We tried to balance pre-fabrication of sub frames with in-situ work off scaffolding to best maintain geometry, optimize detailing and minimize onsite construction duration.”

Construction of the sphere required careful planning and execution, combined with detailed communication and collaboration. Hammerman says the use of glass was essential.

“Transparency is critical to fostering public connections and integrating with the urban streetscape,” he says. “For the Sphere Building we designed a dramatic, exuberant experience transporting visitors to another world, much like the films projected in the theater within … Glazing partially shrouds the massive isolated concrete shell structure, creating a wonderful interplay of shadows, reflections and refractions. Glazing continues up overhead forming an articulated lightweight grid shell dome. Refined steel lattice work and glazing create an ethereal veil, providing shelter while maximizing panoramic views outwards toward the sky and Hollywood …”

Roman Schieber, associate director ppa., with Knippers Helbig, agrees, explaining his firm was responsible for designing and engineering the sphere from concept phase to shop drawings and signed and sealed engineering calculations.

“Every little detail received full attention and was designed with high enthusiasm in a collaborative approach between the architects and us as the consultants and engineers of the dome,” says Schieber.

He says the architectural desire to create a lightweight and highly transparent structure for the glazed dome created some challenges from an engineer’s perspective.

“The diameter of the dome is about 150 feet, and the diameter of the thickest tubular framing member is just 4 inches— smaller than most curtainwall mullions,” he says. “This was only made possible by creating a highly efficient shell structure, which resulted in a self-weight of just 8 pounds/square foot.”

The dome features 1,500 lites of glass in 146 different sizes and shapes, constructed with low-iron, laminated, tempered glass fabricated by Saint-Gobain in Austria, and incorporating Saflex Structural (DG41) PVB interlayers. Knippers Helbig designed a unique structural shell with a shingled glazing system to accommodate the complex geometry and high load requirements of the dome. This includes a single-layered, braced steel structure covered in shingled glass panels—two lites per grid. In all, the glass dome spans nearly 30,000 square feet.

“The entire dome of the Dolby Family Terrace is basically cut in slices, strictly following an East-West direction, resulting in a kind of rectangular structural steel grid with diagonal bracing members,” says Schieber. “A secondary arch-like framing member follows the structural framing member in an East-West direction providing support to the glazing system. These 2.5-inch wide steel T profiles are custom-welded sections with a curved inner edge and a shingled outer edge.”

He explains that the glass lites consist of 2- by 12-mm heat-strengthened panels with a structural PVB interlayer that are 2-side supported on the secondary framing members, and stepped at the non-supported open edge.

“Deadload support is screwed into the secondary framing member, supporting the inner ply of the laminated glass. That means the outer glass pane is only supported through the interlayer,” he says.

Because Los Angeles is earthquake prone, the dome’s superstructure is supported by base isolators, which allow the structure to move by up to one meter during the swaying and racking of a seismic event.

“First of all, the super structure of the Sphere Building stands on some base isolators; this relaxes the requirements for the glazing system during a seismic event,” Schieber says. “However, seismic events are still the governing scenarios for the design of the steel glass structure. In our structural models we investigated various seismic scenarios and determined maximum rhombic distortion of the structural grid. Together with Gartner we built a racking mock-up and investigated such a scenario where the steel grid with the secondary framing members were distorted by hydraulic jacks and it was proven that the system will stay intact under high deformations.”

Attention to Detail

Hammerman pointed out that the project’s location in a sunny climate brought a number of design considerations.

“We strove to create comfortable conditions passively without sacrificing transparency. Large openings, operable vents and coated roller shades were developed and deployed, with guidance from computational fluid dynamics analysis performed by Transsolar, to help accelerate natural air flow patterns including the use of stack effect to naturally vent the space.”

As building projects continue to become more complex, software will continue to be an important tool.

“Even if the geometry of the spherical shape looks simple at first sight, it turns into a highly complex geometry the closer you look,” says Schieber. “Basically, every single detail has a unique geometry, so the development and transfer of geometry information from the master model to fabrication required 3D design tools through all design phases with well-coordinated interfaces between architects, consultants and contractors.”

He continues, “Projects like this one can simply not be engineered without sophisticated design and engineering tools.”

Ellen Rogers is the editor of USGlass magazine. Follow her on Twitter @USGlass and like USGlass on Facebook to receive updates.

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