Currently Reading

Thrown For a Loop in China

Thrown For a Loop in China

Arup engineers use performance-based structural design to pull off Rem Koolhaas's 'drunken towers' for Beijing's CCTV Headquarters.

By By Dave Barista, Managing Editor | August 11, 2010
This article first appeared in the 200810 issue of BD+C.

While the Bird's Nest and Water Cube captured all the TV coverage during the Beijing Olympics in August, the Rem Koolhaas-designed CCTV Headquarters in Beijing—known as the “Drunken Towers” or “Big Shorts,” for its unusual shape—is certain to steal the show when it opens next year.

The Dutch architect's scheme for the $730 million, 4.8-million-sf building, which will serve as the new headquarters for China's state-run television network, essentially folds and twists the traditional skyscraper form into a parallelogram-like shape.

The result is a single loop composed of four horizontal and two vertical sections that connects CCTV's news, broadcasting, administration, and program production departments. Koolhaas's goal is to create an environment that forces everyone in the television business—creative types, producers, technicians, and administrators—to interact in hopes of producing better programming more efficiently and economically.

The novel design, with its large, nine-story base, also provides multiple social “touch points” with the public to encourage passersby to engage with the building, according to Ole Scheeren, Office for Metropolitan Architecture's partner-in-charge on the project.

Because OMA's unusual geometric scheme does not meet Chinese building code, the project structural engineering team, led by London-based Arup with the East China Architecture and Design Institute (ECADI) as local design institute of record, had to employ a performance-based design approach. As part of this process, engineers had to convince a panel of experts that the structure would not only withstand major seismic and wind events, but also hold up during construction—a significant challenge, given that the sloping vertical towers had to be connected at the top.

“The unprecedented structural design underwent the most rigorous internal and external scrutiny during a two-year span, including an expert panel review by China's Ministry of Construction,” says Rory McGowan, Arup's project director on the CCTV project.

Unlike traditional vertical high-rise construction, where the building's core serves as the primary support, Arup engineers had to utilize the building's external face as the superstructure, creating what is essentially a “continuous tube” composed of a series of steel diagonal braces, or X braces, that work in conjunction with a regular grid of columns and edge beams. This braced tube approach provides ample strength and stiffness in the towers to deliver the loads to the base, and the proper stiffness in the base to reinforce the lower tower levels and deliver loads to the foundation. It also accommodates forces from bending and twisting between the two towers, and provides the leaning towers ample stiffness during construction, allowing them to be safely constructed within tight tolerances before they were connected and propped off each other.

The distribution of the diagonal bracing is not uniform, however. Using 3D modeling software, engineers were able to make the structure as efficient as possible based on load calculations. For instance, the amount of X-bracing was doubled around heavy-loaded zones, such as the “armpits,” and halved around light-loaded zones, including the uppermost portion of the building.

“Varying the bracing density allowed us to fine-tune the structure to ensure it was not too stiff to minimize seismic loads,” says McGowan. The Arup team worked closely with OMA to express this optimized X-bracing pattern in the building's façade.

Internal steel columns extend from the foundation up to the furthest reaches of the building, providing support for the floor plates. Due to the slopping nature of the towers, the vertical columns could not extend continuously from top to bottom. To transfer the load from one series of columns to another, the team designed a system of two-story-deep transfer trusses located three-quarters of the way up the building. A similar approach was employed to support the floor plates in the cantilevered overhang.

Early on, the Building Team considered sloped vertical cores to provide a consistent floor plate layout. But finding a sloped elevator system for a building of this scale was difficult.

“We also learned that having different floor plans actually allowed more flexibility in terms of planning for studios, editing suites, and so on,” says McGowan. Therefore, the final scheme steps straight vertical cores so that they always sit within the footprint of the sloping towers.

The main towers sit on a hybrid piled raft foundation system that shares the total load coming from the superstructures between a 7½-meter-thick concrete platform, or “raft,” and a series of 1.2-meter-diameter piles that extend 52 meters into the soil. The foundation system is arranged so that the center of the raft is close to the center of load at the bottom of each tower, and no permanent tension is allowed in the piles. Limited tension in certain piles is permitted during a major seismic event.

For the nine-story base and three-story basement, a traditional raft foundation is used, with tension piles between column locations to resist uplift from water pressure acting on the deep basement. Fifteen- to 20-meter-long tension piles are arranged under the raft with additional piles under secondary cores and columns supporting large transfer trusses from the studio areas.

Related Stories

Building Owners | Aug 23, 2023

Charles Pankow Foundation releases free project delivery selection tool for building owners, developers, and project teams

Building owners and project teams can use the new Building Owner Assessment Tool (BOAT) to better understand how an owner's decision-making profile impacts outcomes for different project delivery methods.

Fire-Rated Products | Aug 14, 2023

Free download: Fire-rated glazing 101 technical guide from the National Glass Association

The National Glass Association (NGA) is pleased to announce the publication of a new technical resource, Fire-Rated Glazing 101. This five-page document addresses how to incorporate fire-rated glazing systems in a manner that not only provides protection to building occupants from fire, but also considers other design goals, such as daylight, privacy and security.

Green | Aug 7, 2023

Rooftop photovoltaic panels credited with propelling solar energy output to record high

Solar provided a record-high 7.3% of U.S. electrical generation in May, “driven in large part by growth in ‘estimated’ small-scale (e.g., rooftop) solar PV whose output increased by 25.6% and accounted for nearly a third (31.9%) of total solar production,” according to a report by the U.S. Energy Information Administration. 

Digital Twin | Jul 31, 2023

Creating the foundation for a Digital Twin

Aligning the BIM model with the owner’s asset management system is the crucial first step in creating a Digital Twin. By following these guidelines, organizations can harness the power of Digital Twins to optimize facility management, maintenance planning, and decision-making throughout the building’s lifecycle.

Sustainability | Jul 26, 2023

Carbon Neutrality at HKS, with Rand Ekman, Chief Sustainability Officer

Rand Ekman, Chief Sustainability Officer at HKS Inc., discusses the firm's decarbonization strategy and carbon footprint assessment.

Mass Timber | Jul 11, 2023

5 solutions to acoustic issues in mass timber buildings

For all its advantages, mass timber also has a less-heralded quality: its acoustic challenges. Exposed wood ceilings and floors have led to issues with excessive noise. Mass timber experts offer practical solutions to the top five acoustic issues in mass timber buildings.

Green | Jun 26, 2023

Federal government will spend $30 million on novel green building technologies

The U.S. General Services Administration (GSA), and the U.S. Department of Energy (DOE) will invest $30 million from the Inflation Reduction Act to increase the sustainability of federal buildings by testing novel technologies. The vehicle for that effort, the Green Proving Ground (GPG) program, will invest in American-made technologies to help increase federal electric vehicle supply equipment, protect air quality, reduce climate pollution, and enhance building performance.

3D Printing | Jun 20, 2023

World's largest 3D-printed building completed in Florida

Printed Farms, known for completing Florida’s first permitted 3D-printed house in Tallahassee, announces the completion of the world’s largest 3D-printed building: a luxury horse barn.

Mechanical Systems | Jun 16, 2023

Cogeneration: An efficient, reliable, sustainable alternative to traditional power generation

Cogeneration is more efficient than traditional power generation, reduces carbon emissions, has high returns on the initial investment, improves reliability, and offers a platform for additional renewable resources and energy storage for a facility. But what is cogeneration? And is it suitable for all facilities?

AEC Innovators | Jun 15, 2023

Rogers-O'Brien Construction pilots wearables to reduce heat-related injuries on jobsites

Rogers-O'Brien Construction (RO) has launched a pilot program utilizing SafeGuard, a safety-as-a-service platform for real-time health and safety risk assessment. Non-invasive wearables connected to SafeGuard continuously monitor personnel to prevent heat exhaustion on jobsites, reducing the risk of related injuries. RO is the first general contractor to pilot this program.


More In Category

Digital Twin

Creating the foundation for a Digital Twin

Aligning the BIM model with the owner’s asset management system is the crucial first step in creating a Digital Twin. By following these guidelines, organizations can harness the power of Digital Twins to optimize facility management, maintenance planning, and decision-making throughout the building’s lifecycle.


Most Popular Content

  1. 2021 Giants 400 Report
  2. Top 150 Architecture Firms for 2019
  3. 13 projects that represent the future of affordable housing
  4. Sagrada Familia completion date pushed back due to coronavirus
  5. Top 160 Architecture Firms 2021