The DeYoung Museum
Artist Rendering of the de Young Museum
Structural Engineer Bret Lizundia and his team at Rutherford & Chekene literally helped the designers of the new de Young Museum weave this structure into Golden Gate Park. Take the roof of the main building, for example. It undulates to simulate the park's sand dunes and forest canopy. Known as the "fifth facade," the roof can be seen from the upper levels of the 10-story tower which crowns this nearly 300,000 square-foot gem.
Covered in a unique copper facade with perforations that mimic dappled light through trees, the building takes the shape of fingers of a hand. Courtyards are interspersed throughout the structure to bring nature into the museum and vice versa.
The Structural Engineers recommended that the main building be base isolated to reduce the floor shaking and potential loss of the art collection that would very likely occur during an earthquake. They also used conventional art collection bracing and anchorage methods. To provide the best structural performance and to be the most cost-effective in decoupling the superstructure from the soil, the structural engineers developed a system of 76 high-damped rubber elastomeric bearings, 76 special flat sliding bearings and 24 nonlinear fluid viscous dampers.
The bearings for the main building rest on concrete pedestals at the intersection of a grid of concrete grade beams. These are founded in the native sand of the site. The bearings support a steel frame structure with lateral loads resisted by steel-braced frames.
Aerial View of the de Young Museum in Golden Gate Park
The museum includes a number of other innovative structural design approaches:
- To make the copper roof a truly visible fifth facade no mechanical or electrical equipment could be placed on the roof. Units were instead placed in the basement.
- The designers wanted the museum to be seamlessly connected to the park, with the top of the finished stone floor matching the exterior grade and with the landscape coming right up to the face of the building. To do this, the structural engineers helped the architect and landscape architects develop a special set of isolation moat cover details so that the many landscape conditions could be accommodated, while still permitting drainage and unhindered movement during an earthquake.
- To bring the park into the museum, there are extensive interior landscaped courtyards, atria, skylights, and diaphragm penetrations. To accomplish this, the Structural Engineers employed a number of number of special long-span framing systems.
The tower's unique design evolved after many architectural approaches and structural systems were investigated. In the final design, the tower rotates 30 degrees in plan as it rises above the main building, with rectangular floors turning into parallelograms. The architecturally exposed concrete is shrouded with perforated copper cladding. The flat slab floors are supported by an elevator core at the center, with girders on the long sides and end walls on the short sides. Some of the tower's unique features and innovative design approaches are:
- The rotating floors result in end walls that tilt more than 16 degrees from vertical. In order to reduce the likelihood of an individual wall ratcheting in the direction of tilt during an earthquake, the walls were vertically post-tensioned with high-strength steel strands.
- The upper floors have full-length glazing on the long sides. Deep girders up to 80 feet long were used to span the distance between end walls and were also post-tensioned with high strength steel strands.
- The slender aspect ratio of the tower creates significant seismic demand on the foundation. The Structural Engineers made use of special foundation systems in order to accommodate these demands with the sandy soils.