February 12, 2021

FOR IMMEDIATE RELEASE

CHICAGO - The steel design community suffered a huge loss Thursday when Leslie E. Robertson, whose career came to be defined by his work on the World Trade Center, died following a diagnosis of blood cancer.

“Les had such a cordial influence on others, including for me personally,” said Charles J. Carter, SE, PE, PhD, president of the American Institute of Steel Construction. “I first met him as an undergraduate student when he agreed to meet for a morning to discuss his recently completed Bank of China building. He made the whole concept of the building lateral system clear to me (as a student!) in about 20 minutes with just a few sketches and a brilliantly simple physical experiment that proved he found a creative way to eliminate column bending.

“We've lost a giant whose work will continue to speak volumes for generations to come,” Carter said.

Robertson won AISC’s J. Lloyd Kimbrough Award in 2001. The award, named for AISC’s first president, honors engineers and architects who are universally recognized as the pre-eminent steel designers of their era. It is the highest honor AISC gives designers; only three other people have received the Kimbrough Award since 2000.

Robertson was in his 30s when he and John Skilling took on the World Trade Center project--his first high-rise structure. He designed an innovative framing system that used closely-spaced exterior steel columns and long-span steel floor trusses to create large, open, column-free spaces.

On September 11, 2001, those towers withstood the impact of fully loaded, high-speed aircraft that were much larger than the Boeing 707 Robertson had considered during the design process. Thousands of people were able to escape before the towers collapsed, but Robertson was haunted by their fall. (The movie night at the 2019 NASCC: The Steel Conference featured the documentary “Leaning Out,” which focused on not only Robertson’s reaction to the World Trade Center attacks but on his remarkable career as a whole.)

AISC extends deepest condolences to Robertson’s family and his colleagues at Leslie E. Robertson Associates.