Project Description
The twin towers at the New Century Plaza are the tallest buildings in California outside of downtown Los Angeles or San Francisco. The $2.5 billion development included retrofitting the historic Fairmont Hotel and new construction of twin 46 level residential buildings above three levels of below grade parking. The Fairmont Hotel along Avenue of the Stars was designed by world-renowned architect Minoru Yamasaki who was also responsible for the triangular shaped 44-story Century Plaza Office Towers on the opposite side of the thoroughfare. To pay homage to Yamasaki, design architect Pei Cobb Freed & Partners shaped the decks of 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. The design extends and dramatizes the visual axis established by the orientation of Yamasaki’s twin office towers toward the earlier hotel.
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 mimic the circles used to shape the reuleaux tower decks to follow above. 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. With over 1 million square feet on the 6.13-acre site the Fairmont hotel 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. The development received the LEED Silver certification from the USGBC.
Description of Concrete Usage
Largo began construction by pouring seven 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 largest pour was even further from the street and required five placing booms and two boom pumps to place 9,367CY over 16 hours.
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.
During the below grade portion of the work on the new towers, Largo also retrofitted the adjacent Fairmont Hotel. Reinforcing and strengthening the exterior basement levels with an additional 8in of shotcrete after drilling and epoxying 41,000 dowels. The scope also included in-fill on metal deck and shotcrete walls to incase the new structural steel.
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 hexagonal shaped perimeter column forms were designed so that they could be stripped horizontally, from underneath the deck. This allowed the deck formwork to be completed before the column forms were poured and stripped.
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 restriction reduced the number of individuals in each manlift for social distancing measures.
Largo Concrete worked a total of 760,000 manhours producing 1.7m square feet of with 151,000 CY of Concrete.
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Негізгі бет Century Plaza 2022 ACI Award - High-Rise Category
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