Background: Fazlur Rahman Khan (Bengali: phjlur rhmaan khaan, Fozlur Rohman Khan) (3 April 1929 - 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of tubular designs" for high-rises, Khan was also a pioneer in computer-aided design (CAD). He was the designer of the Sears Tower, since renamed Willis Tower, the tallest building in the world from 1973 until 1998, and the 100-story John Hancock Center. Khan, more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the 20th century.
Context: Among Khan's other accomplishments, he received the Wason Medal (1971) and Alfred Lindau Award (1973) from the American Concrete Institute (ACI); the Thomas Middlebrooks Award (1972) and the Ernest Howard Award (1977) from ASCE; the Kimbrough Medal (1973) from the American Institute of Steel Construction; the Oscar Faber medal (1973) from the Institution of Structural Engineers, London; the International Award of Merit in Structural Engineering (1983) from the International Association for Bridge and Structural Engineering IABSE; the AIA Institute Honor for Distinguished Achievement (1983) from the American Institute of Architects; and the John Parmer Award (1987) from Structural Engineers Association of Illinois and Illinois Engineering Hall of Fame from Illinois Engineering Council (2006).  Khan was cited five times by Engineering News-Record as among those who served the best interests of the construction industry, and in 1972 he was honoured with ENR's Man of the Year award. In 1973 he was elected to the National Academy of Engineering. He received Honorary Doctorates from Northwestern University, Lehigh University, and the Swiss Federal Institute of Technology Zurich (ETH Zurich).  The Council on Tall Buildings and Urban Habitat named one of their CTBUH Skyscraper Awards the Fazlur Khan Lifetime Achievement Medal after him, and other awards have been established in his honour, along with a chair at Lehigh University. Promoting educational activities and research, the Fazlur Rahman Khan Endowed Chair of Structural Engineering and Architecture honours Khan's legacy of engineering advancement and architectural sensibility. Dan Frangopol is the first holder of the chair.  Khan was mentioned by president Obama in 2009 in his speech in Cairo, Egypt when he cited the achievements of America's Muslim citizens.  Khan was the subject of the Google Doodle on April 3, 2017, marking what would have been his 88th birthday.
Question: What was he the chair of?

Answer:
the Fazlur Rahman Khan Endowed Chair of Structural Engineering and Architecture honours Khan's legacy of engineering advancement and architectural sensibility.