Steel Construction Vol 40 no 6 - International Steel Structures | Page 11

SAISC PROJECTS San Francisco’s new Zuckerberg General Hospital effectively combines state-of-the-art seismic engineering and medical technology with features designed to provide compassionate care for patients. set out in California Senate Bill 1953 (passed in 1994). The new general acute care facility, which opened this past spring, provides the most up-to-date equipment and technology in full diagnostics and treatment departments, while doubling the capacity of the new emergency department. Base isolation ZSFGH is the only Level 1 trauma center in San Francisco County, so its seismic resiliency is paramount. The project team decided early in the design process to integrate base isolation – one of the most advanced earthquake-resistant methods in use today – in the design of the steel-framed building. Steel is an ideal framing material for a base-isolated structure because steelframed floors are relatively lightweight, greatly reducing the demands – especially uplifts – on the base isolators and foundations. The steel superstructure is supported on 115 triple-pendulum bearings (manufactured by Earthquake Protection Systems), a pioneering isolator type that allows the building to slide 30 in. in any direction. Around the perimeter of the building, a 3-ft-wide moat between the top of the mat foundation and the finished grade accommodates movement of the isolated structure. In the event of a major earthquake, the new hospital is designed to remain fully operational and serve as an emergency response center. This project challenged the common perceptions that base isolated buildings are too expensive or take too long to build, proving that with proper planning and close collaboration among team members, base isolation can be a cost-effective system to integrate into a building without increasing the project schedule. For ZSFGH, the City adopted integrated project delivery (IPD), assembling the design team and general contractor to work collaboratively during design, which helped to compress the project schedule to meet the Senate Bill 1953 deadline. ABOVE: A 35-ft-diameter steel halo sculpture stands at the ground-level entry of the hospital campus. OPPOSITE PAGE FAR LEFT: Lukki Lam ([email protected]) is a senior structural engineer with Arup and the project engineer for Zuckerberg San Francisco General Hospital and Trauma Center; Eric Ko ([email protected]) is a principal with Arup, project director and structural engineer of record. OPPOSITE PAGE BELOW: The new Zuckerberg San Francisco General Hospital and Trauma Center is a steel-framed, base-isolated seven-story building. The IPD method facilitated a number of cost- and time-saving strategies. For example, the design team implemented prototype BELOW LEFT: A trussed pedestrian bridge links the new hospital building to the original medical facility. bearing testing in the early design phase of the project, which BELOW RIGHT: Steel canopies at the top of the sunshade fins are visible from the rooftop terrace garden. was made possible by efficiently identifying the best bearing type Perretti and Park Webcor Builders Steel Construction Vol. 40 No. 6 2016 9