ENR California Best Projects 2018 Cultural/Worship: Rex's Roar at the San Diego Zoo
Rex’s Roar at the San Diego Zoo
Owner: San Diego Zoo Global
Lead Design Firm: Ferguson Pape Baldwin Architects
General Contractor: Swinerton
Civil Engineer: Snipes Dye
Structural Engineer: Thornton Thomasetti
MEP Engineer: Coffman Engineers Inc.
The namesake of the San Diego Zoo’s latest 5,000-sq-ft renovation is a 27-ft-tall bronze sculpture of Rex the Lion landing on his front left paw at a 30-degree angle.
The cantilevered structure is supported by the 50-ton footing that Rex rests his paw on, as well as a stainless steel skeletal frame inside the lion’s bronze body. To erect the animal in such a pose, in a highly seismic area, the team designed a custom steel tube to be welded from individual plates and inserted into the paw.
The project team used 3D printing to scale the lion sculpture from a 12-in. model to a 7-ft model, and finally to the real-life 27-ft statue. This process involved scanning and printing 200 rubber pieces, totaling more than 4,000 hours of 3D printing. Those individual rubber pieces were then used to create hollow wax molds, which were coated in ceramic and cast in bronze. The 200 bronze pieces were then welded together to make up the exterior shape of the lion. The final connection between the tube in the paw and the 50-ton footing was built on site and had to be installed within a 1/8-in. tolerance.
Inserting a 10-ton lion at a zoo entrance that receives more than 3.5 million visitors annually presented challenges. Most of the work took place during the day, with no access for construction activity outside the perimeter barricades. All crews, equipment and material needed to be within the barricades prior to 8:30 a.m., when most of the guests started to arrive.