Leslie E. Robertson (1928-2021) - Renowned Structural Engineer of World Trade Center

A decorated figure within the Structural Engineering profession, Leslie ‘Les’ Robertson passed away, aged 92, on February 11th 2021 in San Mateo, California.

Robertson, who pioneered the structural design of tall buildings, was the master-mind behind the design of the iconic towers of the World Trade Center, which stood tall in New York, until Sept. 11, 2001.

Leslie Robertson, a graduate of the University of California at Berkeley, had partnered with John Skilling  when they were awarded the design of the structural system of two twin towers downtown Manhattan, New York. The project, which was the first high-rise he had worked on until that moment, proved to be a defining moment for Robertson, who then went to become a leading pioneer in the field of innovative structural design of tall buildings. Some of his most notable projects are the following:

• U.S. Steel Tower (Pittsburgh, PA)
• Shanghai World Financial Center (Shanghai, China)
• Puerta de Europa (Madrid, Spain)
• Bank of China Tower (Hong Kong)
• Meyerson Symphony Center (Dallas, TX)
• Miho Museum and Bridge (Kyoto, Japan)

U.S. Steel Tower (Pittsburgh, PA) (left) - Puerta de Europa (Madrid, Spain) (center) - Bank of China Tower (Hong Kong) (right) (credits: Wikipedia)

Robertson founded the leading structural engineering firm LERA Consulting Structural Engineers (originally Leslie E. Robertson Associates or LERA). Through its ranks, he spearheaded major structural engineering design innovations, several of which are now considered engineering standards. Some of these innovations are:

• use of a composite megastructure space frame to resist excessive wind loads and carry the weight of the building (Bank of China Tower, 1989)
• use of prefabricated multiple-column and spandrel-wall panels to allow column-free interior spaces and resist lateral force generated by hurricane winds (World Trade Center, circa 1972)
• creation of the shaftwall system, widely adopted for fire-resistive walls in high-rise buildings.
• creation of mechanical damping units to minimize sway of high-rises during heavy wind events.

Robertson’s practice bridged engineering theory with technological advancements thus allowing the conceptual capture and design of more complex and architecturally innovative buildings.

Leslie E. Robertson (credits: LERA Consulting Structural Engineers)

Leslie Robertson was a distinguished member of the Structural Engineering community. He was a member of the National Academy of Engineering, and a Distinguished Member of the American Society of Civil Engineers. He received many public and industry awards, including the Mayor’s Award for Excellence in Science and Technology for his structural design of the World Trade Center, the 1989 Award of Excellence from Engineering News-Record, the Henry C. Turner Prize for Innovation in Construction Technology from the National Building Museum (2002), and a John Fritz Medal from the American Association of Engineering Societies (2012). He served on the board of New York City’s Skyscraper Museum, and the Architectural League of New York. In 2017, he published his memoir, titled “The Structureof Design: An Engineer's Extraordinary Life in Architecture”.