Attendees enjoy both the structural commentary and the anecdotes of the Burj Khalifa's design process
Presenter Bill Baker discusses the Burj Khalifa footprint
SEFW Chair Howard Burton welcomes attendees to the Forum
Fall Forum 2012
SEFW hosted Bill Baker P.E. S.E., Partner-in-Charge of Structural Engineering for Skidmore, Owings & Merrill, at its annual Fall Forum at Benaroya Hall on October 11, 2012. About 250 attendees were able to enjoy his engaging presentation, “Creating the Language of Architecture: The Role of the Structural Engineer.”
Mr. Baker began his presentation by sharing examples of historical structures and noting that architecture conveys a story of both time and place. Early designers were limited by the materials and technologies available – as a result arches and closely-spaced columns were the predominant design elements. Baker contrasted this with the current state of the profession where technology has facilitated much advancement, particularly with respect to the design of tall buildings. While computer analysis programs can be a tool in the design of complex structures, Baker posited that this same technology can be an enabler of bad design decisions. Baker stressed that structural engineers must be active participants in the design of iconic structures. By having their own design philosophy, structural engineers can add to the design process and ensure their values are represented in the completed project.
Baker’s suggestions as to how individual engineers can establish a design philosophy included studying past engineering solutions and identifying simple concepts that describe a design (such as the bundled tube of the Sears Tower or the buttressed core of the Burj Khalifa). He also encouraged that all engineers maintain expertise in classical analytical tools such as the conjugate beam method and the principle of virtual work, as these allow for an intimate understanding of the link between design and analysis. Baker is perhaps best known as the structural engineer of record for the Burj Khalifa, the reigning tallest building in the world. He took the opportunity to share some of his experiences working on the iconic project.
The project began with a design competition in 2003 and an initial height of 1,700 feet. Tall buildings are typically controlled by wind loads and the shape of the individual floor plates significantly influences the resultant wind loads on the building. Through the use of advanced analysis and wind tunnel tests, the height of the Burj Khalifa progressed to the current height of 2,717 feet — over one half of a mile.
Despite this world-record height, the structural systems in the Burj Khalifa are relatively straightforward; it’s largely a reinforcedconcrete shear wall building with flat slab floors. A hexagonal concrete core is located at the center of the building; this provides the torsional resistance for the structure and houses nineteen elevator shafts. Concrete shear walls are located within each of the three wings and these serve to buttress the central core and resist overturning loads. Through the use of outrigger floors every 30 stories, both gravity loads and overturning demands are managed such that there is no net uplift demands at the foundation level. This greatly eased construction of the pile-supported concrete mat foundation.
Baker concluded his presentation by encouraging all design professionals to consider how their personal design philosophy is reflected in their current projects. He stressed that, as engineers, we each have a public obligation to add value through our designs. With a warm and lengthy round of applause, the audience thanked Baker for his thought-provoking lecture.
The SEFW Board of Directors, led by Chair Howard Burton, are grateful for the 40 firms that donated to the 2012 Fall Forum. Their contributions fund many educational outreach efforts, including the Forum series. They are as follows: