The eight level commercial office development on 345 4th Street topped out in San Francisco this month with GC Stoer Construction. The building will be occupied by WeWork, one of the leading space-as-a-service platforms providing flexible real estate options to businesses of all sizes. Designed by Stanton Architecture and DCI Engineers, the building provides 50,000sf of office space and retail storefront at street level. Located in the South of Market (SoMa) District, the downtown skyline will be visible to the north from the vegetated rooftop terrace.
Largo Concrete topped out at the Natiivo tower in downtown Austin, TX earlier this month. Located at the edge of the rapidly growing Rainey Street District, the 442,668gsf building is 33 levels all above grade. The first nine levels of the building are dedicated to parking with 24 levels of residential above holding 248 units.
All units come fully furnished with hotel licensing and can be offered as short-term rentals with building management providing hotel-like services and amenities. In addition to on-site concierge, housekeeping and laundry services the building also features a 18,000sf open air terrace on the 10th floor and a rooftop pool with cabanas and fireplace seating areas.
In total Largo poured 20,000CY of concrete over the course of 15 months with 130,000 manhours. The building is designed by STG Design and Cardno Haynes Whaley structural engineers and general contractor AECOM Hunt expect to have the project complete during the summer of 2021.
The Entrada Creative Office in Culver City, CA 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. The podium level is dubbed the “Sky Deck” and features a 14,000sf landscaped amenities space with a fitness center, conference room and open space for all tenants to enjoy. The 815,000gsf building along Centinela Avenue is clad in glass and metal screens with exposed concrete interior columns and walls. Drivers along I-405 will be drawn to the open-air private balconies stepping up the commercial levels on either side of the building. 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 load of the cantilever deck is carried by a massive structural post-tensioned upturn beam located on the West edge of the roof.
Beneath the surface the Entrada development began with three mat foundation pours averaging 4,500CY. 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 hold 1,044 stalls and 695CY of shotcrete walls line the perimeter of the basement.
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 readymix 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 11,000sf 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 company supplying the voids was BubbleDeck North America.
The corner cantilever at the Sky Deck level required shoring from street level to remain in place until the 3’ wide by 10’ tall upturn beam on the roof deck 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.
Largo poured over 47,000CY in the structure over 11 months. General contractor KRPS, Gensler architects and Saiful Bouquet structural engineers aim to have the project complete in the first quarter of 2021 making it the first, large scale structural bubble deck system on the West Coast.
Due to the amazing range of candidates in our summer intern program, Largo expanded the award for our Summer Intern Scholarship Application. We would like to congratulate Mohammad T. Ali Adib for winning the first place, $10,000 award. Our carpenters apprentice Jennifer Knickerbocker was also awarded with a $5,000 scholarship. And finally, our interns Luke Martin and Brandon Montiel each received a scholarship award of $2,500. We were lucky to have so many outstanding interns this year. We are grateful to teach and learn alongside the future leaders of the construction industry!
The Decorative Concrete Council awarded the Disney Frontierland Expansion project the “Cast in Place Special Finishes Over 5,000SF” this week in a virtual ceremony.
The New Century Plaza Towers became the tallest buildings in Century City, CA this month when Largo Concrete topped out at level 46. In addition to constructing the twin towers simultaneously, Largo also retrofitted the historic Fairmont Hotel designed by world-renowned architect Minoru Yamasaki along Avenue of the Stars. Yamasaki was also responsible for the triangular shaped 44-story Century Plaza Office Towers located on the opposite side of the main thoroughfare. In an effort to pay homage to Yamasaki, design architect Pei Cobb Freed & Partners shaped the new towers as reuleaux triangles. A figure consisting of three circular arches, formed from the intersection of three circular disks, each having its center on the boundary of the other two.
Largo began construction during the summer of 2018 by pouring seven large mat foundations, two of which were we over 9,300CY. Limited access to the site meant much of the readymix for the large pours had to be piped in from Constellation Way to placing booms mounted on tower crane foundations. The first of these two pours utilized five truck mounted boom pumps and two placing booms to place 9,509CY over the course of 16 hours. The second large pour was even further from the street and required five placing booms and two boom pumps to place 9,367CY over 16 hours.
The first four levels out of the ground are dedicated primarily to 1,345 parking stalls and back-of-house facilities. Radius vehicular ramps and grand staircases exude the circles used to shape the reuleaux tower decks to come above. A 25’ tall radius transfer beam supports 30 columns opening up the loading dock space. Formwork supplier Peri USA assembled a temporary access bridge to deliver rebar from Constellation Way to the back of the site. In addition to reducing the amount of crane time the temporary bridge also minimized vehicular traffic along the privately owned Solar Way.
The twin towers rise from the exquisitely landscaped plaza level lined with retail shops and cafés for a pedestrian experience which continues through the hotel lobby to Avenue of the Stars. The towers were constructed concurrently with crews pouring a deck on alternate towers every two days. A custom PERI ACS 400 core wall, self-climbing interior system with gantry beams suspending the exterior formwork was used for the hexagonal-shaped core walls. A radius trolley trailer beam was suspended from the core climber to facilitate construction of the steel framing inside the tower lobbies. The entire system weighed over 360,000lbs.
A column mounted cocoon screen with attached roll-back column formwork enclosed the upper floors as they were being constructed which removed re-shoring and enhanced safety on the site. The perimeter column forms were designed so that they could be stripped horizontally, from underneath the deck, which allowed the deck formwork to be completed before the column forms were poured and stripped. Largo also self-formed the masonry scope of work placing 102,000 concrete masonry units throughout the building including the entire height of the core.
In an effort to ease the strain on vertical transportation between the two towers, teams utilized a temporary 60’ pedestrian bridge spanning the two structures beginning at level 30 and moving up to level 43 as the buildings progressed. This proved especially helpful once Covid-19 reduced the number of individuals in each manlift for social distancing measures.
When complete, the $2.5 billion revitalization project will be over 1 million square feet on the 6.13-acre site. The Fairmont Century Plaza will feature 400 hotel suites with 63 private residences on the upper levels and the towers will hold 290 luxury condominiums with multi-level penthouses. Largo Concrete will have worked 760,000 Man Hours placing 151,000 CY of Concrete! General contractor Webcor is working with Gensler and Harley Ellis Devereaux Architects and structural engineer Englekirk to have the development open during the summer of 2021.
Largo recently topped out at the Uptown Parking Structure in Whittier, CA. The project is located on the east side of Comstock Avenue between Bailey and Philadelphia Street. The structure is being built to support the vibrant downtown commercial and entertainment area along Greenleaf Avenue.
Standing four levels above grade, the structure holds 351 parking stalls across 122,083gsf. The facade along Comstock was designed to compliment the Uptown architecture utilizing plaster, exterior insulation finishing systems (EIFS) and red brick to achieve the desired look. The elevator cores on either side of the building are structural steel with metal stud framing and brick veneer. The stairs along Comstock are cast-in-place while the stairs in the back of the building are steel.
Largo is the general contractor for this project self-performing the concrete formwork, pumping, place and finish, and masonry scopes of work. Largo is working for the City of Whittier to have the structure open before the end of the 2020.
Largo Concrete supports Hope Builder’s mission of empowering Orange County’s young adults with the mentorship, life skills and job skills training that meet the needs of employers. Hope Builders enables young people, who are unemployed, out of school, in and out of the criminal justice system and/or pregnant or parenting, with the job training and life skills needed to move out of poverty and achieve enduring personal and professional success. Since 1995, Hope Builders has worked to develop and refine a theory of change that leads to real transformation in the lives of young men and women who are disconnected from educational and workforce opportunities.
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