San Mateo County Parking Structure Tops Out

Largo Concrete recently topped out at the San Mateo County Parking Structure 2 project with general contractor Truebeck Construction. Located on the southwest corner of Veteran Blvd. and Brewster Ave., the structure will serve employees and visitors of the government services facility in Redwood City. Watry Design acted as the architect and structural engineer on the project and designed the structure to accommodate future parking demand.

The long-span building is designed with a shear wall structural frame and holds 1,022 stall across seven above grade levels. The structure features an exterior half-circle helix ramp 89’6″ in diameter with a slope of 6 degrees. The ramp has 22′ drive isles which are wide enough for two vehicles to pass side-by-side. In addition to reducing the amount of vehicular traffic on the parking decks the express ramp preserves the full footprint of the ground level for alternative uses should parking demand decrease in the future. Level one is designed with 14’11” floor-to-floor heights in order to accommodate human uses.

On long-span parking structure with a park-on-ramp traffic flow crews and equipment can easily move up the building as construction progresses. With the exterior ramp construction following a couple levels behind the decks crews were forced to use a manlift and additional hoisting of material from grade level.

The 345,100gsf structure has a metal screen façade allowing for natural ventilation and 61 electric vehicle charging stations on all levels. A photovoltaic array on the roof deck will offset energy usage from the charging stations. The building is expected to be completed during the first quarter of 2021.

345 4th Street Tops Out

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.

By far the most striking feature of the building is the 77 ft. tall, 28 ft. wide board-formed concrete wall on the West elevation.

Illuminated inset numbers which bare the namesake of the building stand 9′ tall and run vertically down the wall with a smooth concrete finish. The wall was accomplished using shotcrete applied from the interior of the structure onto the boards and around the foam number inserts.

Linea Los Angeles Wins ACI Award for Decorative Uses of Concrete

The American Concrete Institute (ACI) gave the “Decorative Uses of Concrete Construction” award to the Linea Apartments in Los Angeles, CA. Click here to view a list of all the projects which received recognition at this years virtual event and check out the Linea project video below:

The Linea mid-rise luxury apartment complex is centrally located along Sepulveda Blvd. between Pico and Exposition in West Los Angeles. The 545,000gsf development features two levels of below grade parking, three levels of retail and commercial space starting at street level, and residential units from the podium deck up. A total of 911 parking stalls are provided for the 566 market rate and 66 affordable housing units. Residential space is spread out across one ten level and three five level structures rising from the podium. The boomerang shaped nine level structure is located toward the back of the podium and has post-tensioned slabs and a concrete moment frame with both upturned and downturned beams. The five level buildings are light gauge metal stud structures facing Sepulveda Blvd.

The 125,000sf of slab on grade area starts two levels below grade with 1,550CY of shotcrete applied to the perimeter and radial ramp walls of the subterranean parking levels. Due to rebar congestion shotcrete crews utilized a “hybrid method” to place the pilasters in the perimeter basement walls. This is accomplished by forming the pilaster with Stayform then pouring and vibrating readymix into the form without the air component. The Stayform is then removed and the surface is pneumatically applied and finished in the traditional shotcrete fashion. 14,000sf of 22’ tall decks are also featured in the podium structure where teams used Titan XL 625 posts for shoring. During the height of construction in the J-shaped shaped podium Largo had two boom pumps onsite utilizing four masts.

The podium plaza level features a landscaped courtyard with two pools and communal outdoor dining and recreation areas. The modern outdoor living space is decorated with 10,000sf of architectural board-formed concrete parapet walls and planters. The exposed concrete look is carried on to the courtyard roof deck on level ten of the cast-in-place structure, where more concrete benches and board-formed planters can be found lining another pool, a spa, daybeds and cabanas.

Designed by Van Tilburg, Banvard & Soderbergh Architects with Englekirk providing the structural engineering, the development opened during the summer of 2020. The penthouse currently rents for over $15,000/month with impressive views of the I-10 and I-405 interchange. Overall, Largo Concrete placed 53,200CY of concrete over 11 months. 73 elevated deck pours were accomplished over a 9.25-month duration averaging a pour ever 2.7 working days.

Ivy Station Wins ACI Award for Outstanding Performance in Design and Engineering

The American Concrete Institute (ACI) recently awarded the Ivy Station project the award for Outstanding Performance in Design and Engineering. Click here to view a list of all the projects which received recognition this year and check out the Ivy Station project video below:

The new development sits adjacent to the Culver / Venice Metro Line Station in Culver City, CA along Venice and Jefferson Blvd. This city-block-wide transit-oriented development is a true mixed-use project with a commercial office space, hospitality rooms and residential units with a retail plaza at street level. Each component sits atop a three level below grade, 607,000sf parking podium housing 1,538 stalls, 300 of which are dedicated to Metro riders.

The versatility of the podium is also depicted with three different building types rising from the 218,000sf plaza level lined with space for retail and food stores. The 148-room hotel utilizes structural steel while the 200 residential units are spread across wood frame. Both components are five stories tall sitting atop an elevated deck of concrete while the entire commercial building is cast-in-place concrete.

Over 23,600CY was placed for the 236,700sf mat foundation ranging from 17” to 60” thick three levels below the street. Largo utilized their own powerful City Pumps to hose the readymix hundreds of feet from the street down to the jobsite. Nearly 3,000CY of shotcrete walls were pneumatically placed around the perimeter of the basement parking levels. Interior structural walls up to 3’ thick enclose staircases and radial ramps giving pedestrians and vehicles access to the below grade parking.

At the plaza level, structural columns switch from rectangular to circular which juxtapose the angular shaped decks. Typical levels have a 13’8” floor-to-floor height with the first and fifth levels at 15’. The concrete columns, interior walls and soffits remain exposed throughout the commercial building to usher views outward to the street and plaza with a grand entrance off Venice reaching 28’5” in height. Largo worked with general contractor Bernards, KFA architects and Englekirk structure engineers to place 81,500CY of concrete over 14 months.

Natiivo Tower Tops Out at 48 East Avenue

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.

First Major Structural “Bubble Deck” Project on the West Coast Tops Out at Entrada in Culver City

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.

Disney Frontierland Expansion Wins the Decorative Concrete Council’s Award for Cast-in-Place Special Finishes Over 5,000SF

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 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.

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.

Uptown Whittier Parking Structure Tops Out

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.

Yerba Buena Island Condominiums Top Out

Largo Concrete poured the last concrete deck at the Yerba Buena Island Condominiums this month. The project is perched on the small island in the San Francisco Bay best know for its tunnel connecting the two spans of the Bay Bridge. The development begins at the corner of Macalla and North Gate Roads on the northeast side of the island and works it’s way up the hill. The structure is 257,380gsf with 2.5 levels of below grade podium parking and five levels of light gauge metal stud above it. Largo worked with DCI Engineers to deliver the superstructure in a design-build format. Tenants will enjoy views of the self-anchored suspension eastern span of the Bay Bridge with Oakland and Emeryville in the background to the east, and Treasure Island to the north. General contractor Cahill Contractors are BDE Architecture aim to have the development open in early 2021.