BY WILLIAM BAKER, GREG DEIERLEIN,
JERRY HAJJAR, AND MARK SARKISIAN
LESLIE EARL ROBERTSON, who as partner and director of design and construction at Leslie E. Robertson Associates was responsible for all phases of structural design and construction and developed designs of some of the world’s most complex structures, was born on Feb. 12, 1928, and died on Feb. 11, 2021, at the age of 92, a day before his 93rd birthday.
In a career spanning six decades, Les engineered many renowned buildings that expanded the possibilities of both structural engineering and architecture.
Les was born in Manhattan Beach, California, to Tinibel (nee Grantham) and Garnett Robertson. His mother was a homemaker and his father worked various jobs. His parents divorced when he was a young child, and his stepmother Zelda (nee Ziegel), along with his father, raised him. He left high school to join the U.S. Navy in 1945 near the end of World War II and attended the University of California at Berkeley on the GI Bill after his discharge. Les graduated in 1952 with a Bachelor of Science degree.
Although Les never entered direct combat, the deaths in World War II of those he knew led him to become an active pacifist. He was active in anti-war, civil rights, women’s rights, and other protests that at times led to arrests, which he downplayed as a ride to the police station followed by paperwork and his release. In his later years, he organized and sponsored buses for his friends and colleagues to travel with him from New York City to march at protests and other gatherings in Washington, D.C.
Les’ first job was as a mathematician in the electrical engineering department of an Oakland, California, firm, Kaiser Engineers. While at the firm, and under the guidance of the chief engineer, he learned the basics of what would become his passion, structural engineering. During nights and weekends, he spent time teaching himself concepts such as slope deflection and Hardy Cross methods, which led to a deep understanding of the fundamentals of structural engineering. He learned graphical methods that captivated his imagination from his mentor.
In 1958 he joined the civil and structural engineering firm Worthington-Skilling. The firm eventually became Worthington, Skilling, Helle & Jackson and received the structural engineering commission for the New York World Trade Center project, with Minoru Yamasaki as the lead architect. The buildings were designed from 1963 to 1971. Les was only 35 years old when he moved from Seattle to New York to lead the project for his firm, Skilling, Helle, Christiansen, Robertson. Les’ collaborations with Yamasaki led to the development of a perimeter tubular structural steel lateral load resisting frame, where columns were spaced at 3 feet 4 inches on-center, creating a sense of enclosure for people using the building. Interior framing spanned from core areas to the perimeter frame without interior columns, creating column-free spans and flexible spaces for use within. The Twin Towers were completed in 1972 and 1973.
At the outset of the design for the World Trade Center, Les recognized that conventional approaches to wind engineering were not sufficient for the design of what were to be the world’s tallest buildings, located at one of the windiest sites in Manhattan. In 1963, Les attended the first Wind Engineering Congress in the U.K., where he had the good fortune to meet Dr. Alan Davenport (NAE 1987), with whom Les pioneered innovations that would form the basis of performance-based wind engineering. The World Trade Center’s structural system and curtain wall design employed data from wind tunnel tests, which Les and Davenport developed under the guidance of Dr. Jack Cermak (NAE 1973). Les instigated studies of human perception of motion to establish acceptance criteria for building accelerations, which became the basis of tall building design around the world. He subsequently developed and patented viscoelastic dampers that were employed to reduce wind-induced accelerations in the World Trade Center towers.
While in his 30s, Les started leading the design of tall buildings and, with the use of early computers, developed structural concepts and systems that are still used today. He was a structural designer with strong opinions and a winning personality. In addition to Minoru Yamasaki, he had repeated collaborations with world-class architects, including Gunnar Birkerts, Philip Johnson, William Pedersen, and I.M. Pei.
His work includes the structural design of several internationally recognized buildings, including the IBM Building, Pittsburgh; the IBM Building, Seattle; the US Steel Tower, Pittsburgh; the Federal Reserve Bank, Minneapolis; the AT&T Headquarters, New York; the Bank of China, Hong Kong; the Puerta de Europa, Madrid; the Miho Museum Bridge, Shigaraki; the Shanghai World Financial Center, Shanghai; the Lotte World Tower, Seoul; and the Merdeka 118, Kuala Lumpur, which at 679 meters tall is the second tallest building in the world.
The project that the world would most associate him with is the World Trade Center in New York. The Twin Towers were the two tallest buildings in the world when completed in 1972 and 1973. Surviving a truck bombing in 1993, the two towers collapsed on September 11th, 2001, after each was struck by Boeing 767 airplanes loaded with fuel. The buildings survived the initial impacts but collapsed from the resulting fires. Although he wrote, “My sense of grief and my belief that I could have done better continue to haunt me,” the tall building engineering community recognized that what brought the towers down was an attack of exceptional destructiveness, not a deficiency of engineering.
Les was highly respected by the structural engineers with whom he competed for projects around the world. Most viewed him as an inspiration and mentor. With generosity, he would share his thoughts and experiences on issues that ranged from technical to ethical. Many looked forward to his annual holiday card in which he and his wife, SawTeen See, would recount the events of the past year, along with a few comments about politics and society.
In recent years, Les recorded his thoughts and work in his book,The Structure of Design: An Engineer’s Extraordinary Life in Architecture (The Monacelli Press, 2017) and the 2018 documentary film,Leaning Out: An Intimate Look at the Twin Towers Engineer, Leslie E. Robertson.
In addition to his election into the National Academy of Engineering, Les received many honors and awards for his work, including honorary doctorate degrees from Lehigh University, the University of Western Ontario, the University of Notre Dame, and Rensselaer Polytechnic Institute. He received the John F. Parmer Award from the Structural Engineers Association of Illinois and the Distinguished Engineering Alumnus Award from the University of California at Berkeley. Les was a distinguished member and fellow of the American Society of Civil Engineers (ASCE) and received ASCE’s Outstanding Projects and Leaders Award for Lifetime Contributions in Design. He was the first to receive the Henry C. Turner Award for Innovation in Construction Technology and the first recipient of the Council on Tall Buildings Fazlur Rahman Kahn Medal. He was awarded the prestigious Institution of Structural Engineers UK Gold Medal in 2004. He was the first American to be honored since Nathan Newmark, 25 years earlier.
Les is survived by his wife, business partner, and prominent structural engineer, SawTeen See, to whom he was completely devoted; children Chris Robertson, Sharon Robertson, and Karla Mei Robertson; and grandchildren. Les’ daughter, Jeanne Robertson, died in 2015.