Entrada Creative Office
The Entrada Creative Office in Culver City is truly a unique structure combining state-of-the-art design with cutting edge engineering. The building is 13 levels tall, including the roof, with six levels of commercial office space above six levels of parking, one of which is below grade. Parking decks provide space for 1,056 stalls and are accessed by an interior speed ramp. The podium level is dubbed the “Sky Deck” and features a 14,000 sf landscaped amenities space with a fitness center, conference room and open space for all tenants to enjoy. The rectangular office levels are rotated with respect to the lower parking floors, creating a substantial corner cantilever at the west face of the building making a strong architectural statement.
The Entrada development began with three mat foundation pours averaging 4,500 cubic yards. Two of the mass concrete pours at the elevator cores required a thermal control plan to ensure temperatures did not exceed 165 degrees during placement. Parking levels are lined with 695 cubic yards of shotcrete perimeter walls.
Elevated decks are concrete voided slabs or “bubble decks” supported by high-strength cast-in-place columns and walls. Voids are created using hollow spheres made of recycled plastic and arranged in 8’x10’ wire mesh grid prefabricated offsite. Once on site, the grids are placed on a layer of two-way rebar installed on the plywood deck with another layer of reinforcing on top. Deck pours begin by placing the first 4” to 6” of ready-mix to secure the voids in place before the balance of the slab is poured. Elevated decks ranged between 16” to 20,” with typical levels at 18” thick.
The flat plate, bubble deck system allowed architects to maximize floor space in the building, with a typical bay measuring 30’x45’. Flat decks also enhanced production flow by eliminating beams, drop caps, depressions and hanging form build up. On average Largo poured 11,000 sf of deck every other day during the elevated slab duration of the project.
Overall, the voided slab construction reduced the weight of the structure nearly 30% in comparison to conventional methods of waffle slab or post-tensioned decks. This measure not only limited the seismic forces and foundation loads, but also reduced the environmental impact of the project with significantly less material to transport and a faster schedule. The bubble deck system itself enhanced safety onsite by providing a simplistic building to construct with less manhours. The lack of dropheads around columns allowed for enhanced production of deck formwork resulting in fewer work hours and hence fewer injuries. The just-in-time installation of bubble cages, reduced amount of reinforcing and lack of PT cables contributed to a cleaner jobsite.
The load of the corner cantilever at the sky deck level is carried by a massive structural post-tensioned upturn beam located on the west edge of the roof. This element required shoring from street level to remain in place until the 3’ wide by 10’ tall beam was poured and stressed. All six stories of office space and the roof are suspended at this corner from this same upturn beam on the roof. The corner columns of the cantilever have continuous reinforcing from the first commercial level to the roof. This feature required the shoring removal process to be reversed with the upper levels being stripped first while checking for deflection throughout the process.
In total Largo poured over 47,000 cubic yards in the structure over 11 months in the first major bubble deck project on the west coast.
