Bachelor of Science, Greek Technology Military College, 1954. Bachelor of Science, Greek Technology Military College, 1954. Master of Science, Greek Technology Military College, 1958.
Chief structural engineer Ben. Dyer & Associates, Hyattsville, Maryland., 1958-1960. Chief bridge engineer David Volkert & Associations, Washington, 1960-1970.
President L.T. Delyannis & Associations, Arlington, Virginia, since 1970.
Program chairman International Symposium on Concrete Bridge Design, Toronto, Ontario, Canada, 1967, Chicago, 1969. Chairman district advisory council Small Business Administration, 1980-1982.
Member Virginia Board Geology, 1981-1982.
Member Arlington County Planning Commission, 1976—1980. Member inaugural committee Nixon-Agnew Inauguration, 1968, 1972. Alternate delegate Republican National Convention, 1972—2007, 1976.
Chairman Virginia Republican Nationalities Council, 1970—1976. Board director Arlington Dance Theater, 1973—1977. Member of American Society of Civil Engineers, Arlington Chamber of Commerce (bd directors 1983-1991, president 1989), American Hellenic Educational Progressive Association, International Association Bridge and Structural Engineering, American Concrete Institute, Society of America Military Engineers, American Hellenic Institute (secretary-treasurer), American Concrete Institute (committee on concrete bridge design), National Society Professional Engineer, Washington Golf and Country Club, Capitol Hill Club (life).
Married Georgia H. Alexander, February 21, 1957. Children: Theodore, Harry-Michael.