One of the most anticipated and eye-catching buildings in Los Angeles – if not all of the West Coast – opened with great fanfare on June 23, complete with a marching band and a light show displayed on its façade. At 73 stories and 1,100 feet, the Wilshire Grand Center is the tallest building in the U.S. west of the Mississippi. Thornton Tomasetti provided structural engineering and performance-based design services to engineer-of-record Brandow & Johnston for the project as well as model interoperability programming for architect AC Martin Partners, one of Southern California’s oldest planning and architecture firms, responsible for many of LA’s iconic buildings.
Built on the site of the 13-story former Wilshire Grand Hotel, which opened in 1952, the new Wilshire Grand Center kicked off on February 15, 2014, as more than 21,000 cubic yards of tower foundation mat concrete was placed in less than 19 hours. This set a Guinness world record for the largest continuous placement of structural concrete.
To minimize weight and construction time, a mixed system was selected for the tower’s structure. It consists of concrete-filled metal deck slabs carried on steel floor beams that span from an internal concrete core to perimeter concrete-filled steel box columns between hotel rooms. Lateral load resistance is provided by the core- a narrow, nearly rectangular four-cell cast-in-place reinforced-concrete shear wall tube that is supplemented at three levels by sets of transverse outriggers with buckling restrained brace (BRB) diagonals for well-controlled wind and seismic performance. The tower is topped by a glazed steel-framed “sail” sporting LED lighting systems and a steel spire.
Thornton Tomasetti applied performance-based design principles and nonlinear response history analyses to guide the design, validate the tower’s seismic performance, and eliminate prescriptive perimeter moment frames. This allowed floor-to-ceiling glass for great views and natural light.
We also supported a parametric façade panelization strategy for the geometrically complex, all-glass façade. By synchronizing slab and façade geometry between the architect’s Rhino and Revit models, the combined data generated two Revit models: one for the architect’s documentation of façade panelization, and the other with information needed for the façade consultant.
Wilshire Grand Center will play a multifaceted role in the renaissance of downtown Los Angeles. The top two-thirds of the tower houses a four-star hotel with Class-A office space below. A five-story podium holds retail, ballroom and dining facilities, all served by five levels of subterranean parking. Its rooftop “sky lobby” greets arriving guests with sweeping views of Los Angeles that extend from surrounding mountains to Santa Monica and the Pacific Ocean beyond. It also illustrates the wave of global investors coming to L.A., such as Cho Yangho, Chairman of Hanjin International/Korean Air, the owner/developer of the project.
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