Just as the Wilshire Grand Center in Los Angeles is being constructed in an earthquake zone so is the Salesforce Tower in downtown San Francisco. And like the Wilshire Grand, the Salesforce Tower will be constructed to withstand the strongest earthquakes known to the area.
The architectural captivating Salesforce Tower will be more than 200 feet taller than the city’s current highest skyscraper, the Transamerica Pyramid, which opened in 1972. Designed by the world renowned architect, César Pelli, the Tower will be constructed using highly technical “performance-based seismic design.” Even though the Tower sits on an area that used to be a landfill, architect Pelli is quoted as saying, “Towers are inherently safer in earthquakes than low buildings.” He added, “If you know an earthquake is coming run to the tallest building you can find.”
Approved in 2008, the city’s performance-based seismic design is stricter than the state of California’s code. It gives engineers and architects an opportunity to use computer simulations and technical modeling to evaluate a building’s capacity to withstand an earthquake. The SFGate reports that the “main structural advantage is that this allows towers to be built without horizontal beams - known as moment frames - on the outer edge of each floor. Instead, seismic strength is concentrated within the vertical core of the structure.”
Structural engineered by the Seattle firm, Magnusson Klemencic Associates, the Salesforce Tower will contain no moment frame to thicken the exteriors of the 61-story building. Magnusson Klemencic state that the “structural solution was developed using a ‘performance-based seismic design’ approach, a cutting-edge methodology pioneered by MKA to improve performance of high-rise buildings in areas with high earthquake activity.” The Tower was put through a series of 22 computer simulation tremblors that were modeled on real earthquakes that had occurred in the Bay Area. It passed them all including the simulation of the 1906 earthquake that was estimated to be in the 7.6 range.
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