CAMBRIDGE, Mass.—William J. LeMessurier, chairman emeritus and founding partner of LeMessurier Consultants, died on June 14, while recovering from hip surgery at his home in Maine. He was 81.

LeMessurier was renowned for innovative structural engineering and was recognized as a leading authority in the design of tall buildings. He created the concept of the tuned mass damper system to control wind-induced motions which was first used at Citicorp Center in New York City. He also is one of the originators of the "staggered truss" system now widely used for highrise apartments and hotels.

According to the New York Times, "LeMessurier became a hero to other structural engineers when he detected and repaired a potentially catastrophic flaw in the Citicorp building." Books and courses on ethics have evolved because of his ethical behavior regarding this matter.

Concurrently with his professional practice, LeMessurier taught at the Massachusetts Institute of Technology and Harvard’s Graduate School of Design where he was appointed Adjunct Professor in 1982. Though originally trained as an architect, LeMessurier devoted himself to generating a spontaneous professional understanding between engineers and architects.