Reach for the Stars!

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.

Le Conté Apartments becomes UCLA’s Tallest Building

Largo Concrete topped out at the UCLA Le Conté Apartments this summer making it the tallest building on campus. The undergraduate student housing project is located at the corner of Le Conte and Gayley Avenue on the south side of the campus. The south building is 11 cast-in-place levels above grade and the north is 19. The overall project is 301,761gsf and will add 1,167 beds in 192 rooms. General contractor PCL Construction, Studios Architecture and Nabih Yousseff & Associates structural engineers are on track for temporary occupancy in the Winter of 2021.

Miro Towers Become the Tallest Buildings in San Jose

The Miro Towers became San Jose’s tallest structures this month when Largo poured level 29 at 291′ above street level! Located on the north side of E. Santa Clara Avenue between Fourth and Fifth, the buildings are across the street from City Hall which used to be the city’s second tallest structure. Miro will feature a total of 630 two and three bedroom units and 633 parking spaces.

Stressing Procedure

Transfer girders utilize four rows of post-tensioned cables which are progressively stressed throughout construction. The girders are located on level five above grade and are up to 72” wide by 64” deep! The additional rows of PT cables are spaced 6” apart and lay below a row of tendons which are stressed after placing level five. Upon completion of level ten the bottommost row is stressed, then the second from the bottom row is tensioned at level 15, ending at level 25.

Steinberg Hart Architects, DCI Structural Engineers, and general contractor Suffolk Construction are on schedule to have the Miro towers open early 2021.

UCSD North Torrey Pines Living and Learning Center Buildings Three & Four

Largo recently topped out on the North Torrey Pines Living and Learning Center at the University of California, San Diego. The project was designed by HKS Architect, Inc. and Magnusson Klemencic Associates is located on the southeast corner of North Torrey Pines Rd. and Muir College Dr. in La Jolla, CA. Largo’s scope only covered a portion of the overall development with buildings Three and Four consisting of 15 and 14 levels respectively, for a total of 600,000gsf. The development features 2,000 new beds for undergraduate students with related residential life space, new facilities for the Sixth College, social sciences, arts and humanities, dining and retail space, and 1,200 parking stalls. General contractor Clark Construction is aiming to have the development open for the Fall 2020 semester with a LEED Platium rating.

1066 Market Topping Out

Largo topped-out at the 1066 Market street high-rise this week in downtown San Francisco. The building features two levels of below grade parking with 97 total stalls and 4,000sf of retail at grade level. 303 high-end residential units span the following 15 levels above grade. Largo is working with general contractor Swinerton Builders, architect Solomon Cordwell Buenz & Assoc. and structural engineer Nishkian Menninger to have the building open in early 2020.

Miro Mat Foundation Pours

Over the course of the last two Saturdays, Largo poured a total of 13,100 cubic yards of concrete foundations at the Miro project in San Jose, CA. Each pour started at 2:00AM and took over 16 hours to complete using five truck-mounted boom pumps. Readymix supplier Cemex used 93 trucks to deliver over 1,300 loads to the site across the street from City Hall. When complete the development will feature two 28 story towers above three levels of below grade parking. The Miro towers will add 630 new residential units to one of the most expensive housing markets in the country along with 633 stalls of parking. Largo is working with Steinberg Hart Architects, DCI Engineers and general contractor Suffolk Construction toward an opening date in the summer of 2020.

Circa and Disney win Pankow Awards from the American Concrete Institute

The American Concrete Institute’s Southern California Chapter has selected the Disney Frontierland Expansion and the Circa projects for the annual Pankow awards!

Charles Pankow Jr. Award – Circa at 1200 S. Figueroa

The focal point of this $500 million mega-project are the twin high-rises adjacent to the Staples Center in downtown Los Angeles.  26 residential levels sit atop eight levels of podium parking, two of which are below grade, with commercial space at grade level. Designed by architects Harley Ellis Devereaux both towers stand 420’ and hold 648 total units. The 2-acre amenity deck complete with swimming pool and fitness center is located on the podium level above 1,645 stalls of parking. Situated between LA Live, the Convention Center and the Metro Pico Station in the city’s South Park district, the high-rise buildings feature an elliptical north face to enhance views of the skyline and mimic design themes from surrounding architecture.

Structural engineer Cary Kopczynski & Company utilized cast-in-place concrete with post-tensioned slabs which minimizes internal columns for maximum openness. The use of a two-way post-tensioned slab system allowed for continuity of framing between the retail/parking podium and the residential levels above, eliminating the need for transfer beams. A combination of shear walls and ductile frames resist seismic loads.

In June 2015, Largo started by pouring four large mat foundations totaling 15,985CY with ready mix supplier Holliday Rock.  Over the course of 24 months Largo poured a total of 110,000 cubic yards installed by 600,000 man-hours without any days away from work safety incidents.  All this was all accomplished across the street from the home court/rink of multiple professional sports teams and millions of convention center guests.

Outstanding Performance in Design and Engineering Award – Disney Frontierland Expansion

The goal of this project was to prepare the Disneyland park for the new Star Wars attraction. In addition to four tunnels, multiple retaining walls and a marina, Largo’s scope included a concrete trestle bridge for the railroad at the Rivers of America attraction. Although the visual aspect of the end product is exquisite, the details that were put into the fabrication of the two elements of the structure; the columns and hammerheads, and the concrete mix design used to simulate an aged wooden railroad trestle bridge, is also noteworthy.

The columns started in the back lots of Walt Disney Imagineering as an image in the mind of the design team. This image was transformed into approximately 50 lineal feet of hand carved foam positive. This was reviewed by the Disney team to confirm their vision and sent out to Fitzgerald Formliners to confirm that the positive would produce a usable form liner. A number of changes were made in the foam positive to ensure that no negative spaces existed in the positive to allow for smooth removal of the form liner. To allow for proper alignment of the four columns that attached to each of the twelve hammerheads, relative to each other, the column forms were fastened to a wall form.

With all of the details in the form liner, Largo contacted Holliday to discuss the appropriate concrete mix design to ensure a perfect positive from the very detailed form liner. Although self-consolidating concrete is not frequently used in the Southern California Market, it was determined that with the details, the importance of exact alignment of the columns and the limited space within the column form to allow for a vibrator, that this would be the appropriate mix design to yield the best finished product.

4000 psi @ 28 days Self Consolidating Concrete mix with a water to cement ratio of 0.44. The cementitious content was 8.5 sacks that was 70% Type II/V cement and 30% Type F Fly Ash. Nominal spread was 25” to 30” but it was usually in excess of 27”. It has a maximum aggregate size of 3/8”, but since the mix needed to reveal very fine details it was proportioned to contain 70% Washed Concrete Sand. All of the aggregates are from Holliday Rocks Upland California Facilities. The admixtures in the mix design included: a Type F High Range Water Reducing Superplastizing polycarboxylate, a workability-retaining admixture that provides flexible degrees of slump retention without retardation. And when needed (in this case it wasn’t but was always available) a viscosity-modifying admixture that is specially developed for producing concrete with enhanced viscosity and controlled rheological properties that increases resistance to segregation while facilitating placement and consolidation.

The hammerheads that span across the columns were formed out of rough sawn dimensional lumber of varying widths on top of the above-mentioned columns. Each of the twelve hammerheads were formed with no common joint plan of the rough sawn lumber. Steps were taken to raise the texture of the rough sawn lumber. Each board was soaked in water overnight and sealed with form release to accentuate the rough sawn look to the vision of the Imagineers. The hammerheads were also poured with the self-consolidating concrete mix design that was used in the columns.

Typically, these decorative types of concrete elements are a post installed façade covering a structural column, but with the load requirements of the train, envisioned size of the elements and the environmental concerns of the river, the above summarized use of concrete was developed and put to use.

Carte Hotel Tops Out in San Diego

Largo Concrete recently topped out at the Carte Hotel in downtown San Diego. Located at 401 W. Ash this 17 level building features two levels below grade and 14 stories above totalling 174,470gsf. The building consists of 2 levels of underground parking holding 118 stalls, and a conference room, event center, ballroom, gym, four-star restaurant and swimming pool between levels 1 thru 3. 240 total hotel rooms are spread out between levels 4 thru 14 with a rooftop observation deck with view of downtown and the harbor. Working with general contractor DavisReed, Tucker Sadler Architects and PK Associates as structural engineer, the building is scheduled to open during the first quarter of 2019.

Two Residential Project Starts in San Francisco

1066 Market
The Market street development will hold 303 units and 97 parking stalls spread across 3 levels below grade and 16 levels above. Working with general contractor Swinerton Builders, Solomon Cordwell Buenz architects and Nishkian Menninger structural engineers, Largo expects to top our during the summer of 2019.

875 California
A couple miles north, the 875 California development is also being constructed with the same general contractor and structural engineer, with BDE Architecture. The building will house 44 units above 48 parking stalls on 100,000gsf. The structure will be 2 levels below grade and 8 levels above and is expected to top out during the summer of 2019.

Park 5th Tops Out

Across the street from Pershing Square, Largo topped out at the Park 5th development in downtown Los Angeles this week. The building rests on a 4,700CY mat foundation which was poured in August 2017, with two levels below grade and 25 levels above. Patrons of the 347 unit high-rise will enjoy a rooftop deck with a club room, fitness center, a bar/kitchen, TVs, a business center, and an infinity pool with cabanas. Designed by architect Ankrom Moisan and Nabih Youssef & Associates structural engineers, the buildings is seeking LEED Silver certification by the USGBC. Working with general contractor Suffolk Construction the building is scheduled to be open in the first quarter of 2019.

437 S. Hill Podium

The MacFarlane Partners are also developing the site adjacent to the high-rise into a new mid-rise apartment complex. Largo worked with Bernards on this project pouring the concrete in a 5 level parking podium with wood frame above.