Newest San Francisco Landmark Designed to Withstand the ‘Big One’

Although the shaking from the 6.8 magnitude earthquake that rocked Washington on February 28th couldn’t physically be felt by workers on the Asian Art Museum project in San Francisco, it’s safe to say that it rattled a few nerves for those involved in constructing this high-profile rehabilitation and adaptive reuse project. Once completed, the building is designed to be perhaps one of the safest structures around if the “Big One” hits - but its current state is much more delicate as crews carry out demolition, structural and restoration work simultaneously on the project that is passing the halfway mark.

“Once complete, the building is designed to withstand an 8.3 magnitude earthquake, but due to the current state of structural demolition and adaption, the Washington earthquake just made everybody very aware of how fragile the building really is at the moment,” comments Project Engineer Paul Erb.

The conversion of the old San Francisco Main Library into a world-class museum for the Asian Art Foundation represents the first joint venture in DPR history. DPR and Lem Construction Inc. have joined forces to serve as general contractor on the $100 million project, and, despite its myriad of challenges so far, the job has been a testament to the success of this innovative collaboration. The design team is led by the architectural joint venture HOK, LDA Architects and Robert Wong Architect in association with internationally renowned museum designer Gae Aulenti, FAIA, of Italy with Forell/Elsesser as the structural engineer.

In addition to the complete restoration of the exterior facade, interior restoration work will focus on preserving the “great hall” and the grand staircase, or loggia, as well as the historic plaster in core areas. Otherwise, much of the building has been gutted and is being rebuilt to fit the unique needs of the museum. A new floor is being added, and an innovative one-way circulation plan will move visitors chronologically through the history of Asian art.

Given the history of the project site, the installation of an innovative structural system in the building seems prudent. Originally the location of the Yerba Buena graveyard, the parcel next housed San Francisco City Hall, constructed there in the late 1800s but felled by the 1906 earthquake. The Main Library, built on the site in 1917, was condemned after the Loma Prieta Earthquake.

The base isolation system that is being installed has been used less than half a dozen other times in the U.S. for the purpose of retrofitting an existing structure. Its design intent is twofold: to guard against horizontal displacement, as well as to minimize any movement of the building itself to protect the historic $4.6 billion in artwork that the museum will house. The system involves installing approximately 200 isolators on some of the approximately 160 columns throughout the building. One or more isolators each are welded to selected columns, effectively placing the entire building on rubber that helps absorb and minimize the impact of an earthquake.

Project Engineer Ian Pyka notes that installing the isolators, a process that involves four different subcontractors and multiple inspections, has been a challenge. “There’s definitely a learning curve involved,” he comments. “We have to make sure everybody gets in on time and the whole sequence gets completed as scheduled.” Each isolator takes approximately three weeks to install, with a limit of six columns that can be hydraulically jacked at any one time. While the isolator is being installed, the column load is transferred to temporary jacks.

“You have to have some pretty creative sequencing to work your way around the building,” Pyka says. At the same time, a wide range of other work is underway. “Every part of the building has work going on, involving everything from structural steel and concrete all the way to cleaning plaster with a toothbrush.”

The ongoing excavation work has delivered a number of expected surprises, requiring an archaeologist to be present whenever digging occurs. “Due to the geographic history of the site, it is imperative an archaeologist is on site whenever excavation is planned in the event that remains from the old graveyard or the old City Hall Foundation are unearthed,” Erb comments. To date more than 30 skeletal remains have been exhumed and relocated.

Extensive owner changes have added to the project challenges. Open and daily communication has been essential to ensure that the project stays on track, and the Joint Venture team is moving steadily ahead to complete this newest San Francisco cultural landmark.