Thornton Tomasetti Engineers Installation of Cantilevering Leaping Lion at San Diego Zoo
Thornton Tomasetti recently completed engineering work on another high-profile large-scale sculpture, this time at the world-famous San Diego Zoo. At more than 27 feet tall and weighing in excess of 18,000 pounds, the new bronze lion sculpture greeting zoo visitors is said to be the largest cantilevered bronze animal sculpture in the world. Rex’s Roar (Rex for short) was unveiled in late March at the center of the zoo’s newly designed entry plaza. Thornton Tomasetti provided structural engineering services to the Artworks Foundry for the sculpture’s structural steel skeleton and concrete foundation.
Positioning Rex on one paw in a highly seismic area such as San Diego posed some significant challenges. Because no off-the-shelf piece of stainless steel of the right strength and stiffness existed that would fit inside Rex’s leg, a custom heavy tube was welded from individual plates. In addition, the cantilevering bronze sculpture also has to withstand large seismic vertical forces and torques. Because stainless is the stronger material, there are many connections between the two metals to distribute the load out and avoid over-stressing the bronze. The Artworks Foundry uses a type of silicon bronze that is typical for casting and has a yield stress of approximately 20 ksi and a tensile strength of 45 ksi.