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.
