Hardy Cross (10 February 1885–11 February 1959), civil engineer, was born in Nansemond County and was the son of Thomas Hardy Cross, who served two terms in the House of Delegates, and Eleanor Elizabeth Wright Cross. After attending Norfolk Academy, he received an A.B. and a B.S. from Hampden-Sydney College in 1902 and 1903, respectively. Cross taught English, chemistry, and physics at Norfolk Academy from 1903 to 1906. He received a B.S. in civil engineering from the Massachusetts Institute of Technology in 1908 and three years later completed a Master of Civil Engineering degree at Harvard University.
From 1908 to 1910 Cross worked for the Missouri Pacific Railway Company as an engineer in the bridge department. In 1911 he joined the faculty of Brown University as an assistant professor and taught in the engineering department until 1918. Cross then went to New York and Boston, where for three years he engaged in the general practice of structural engineering, particularly the design of bridges and buildings. On 5 September 1921 in Washington, D.C., he married Edythe Hopwood Fenner Bridgham, who had three children from a previous marriage. They had no children of their own.
From 1921 until 1937 Cross served as a professor of structural engineering at the University of Illinois. During this period his innovative ideas changed methods of structural analysis in construction. Cross became famous as a result of his ten-page paper entitled "Analysis of Continuous Frames by Distributing Fixed-End Moments," published in the American Society of Civil Engineers Proceedings (1930). In it, he presented an entirely new method of analyzing complex structural frames used in buildings, bridges, and other structures. After publication of Cross's final version with comments by thirty-eight of his peers in the ASCE's Transactions (1932), he was immediately recognized as having solved one of the most difficult problems in structural analysis. In 1933 the ASCE awarded him the Norman Medal for his paper. Also known as the Hardy Cross method, his moment distribution method greatly simplified the many complicated calculations previously required for computing stress in rigid frames, such as those of reinforced concrete. His technique was quickly adopted and had immense practical importance around the world. Although computer programs later replaced Cross's method, it continued to be taught in engineering departments in the twenty-first century.
In 1932 Cross and Newlin Dolbey Morgan published Continuous Frames of Reinforced Concrete, which presented an elaboration of the former's theory, analysis, and design of buildings and bridges. In Analysis of Flow in Networks of Conduits or Conductors (1936), Cross applied his insights to the design of pipe networks and solved problems of water flow and pressure in municipal water systems. At the beginning of the twenty-first century, computer software for such pipe systems used the Hardy Cross method to make preliminary calculations. Designers of gas pipeline networks also applied the method to their analyses. The translation of his works into many other languages permitted their use worldwide not only in civil engineering but also in other engineering disciplines.
In 1937 Cross began sixteen years as head of the civil engineering department at Yale University. He served on an insurance industry committee that investigated the 1940 collapse of the Tacoma Narrows Bridge into Puget Sound and later published articles on the design of suspension bridges. The Society for the Promotion of Engineering Education (later the American Society for Engineering Education) honored Cross with its Lamme Medal in 1944 for his rigorous training of future engineers. In 1952 he published Engineers and Ivory Towers, a collection of articles, speeches, and graduate lectures in which he emphasized the importance of good engineering to social welfare. Cross wrote numerous other articles and reports, and a collection of his most significant works appeared posthumously in a volume entitled Arches, Continuous Frames, Columns, and Conduits: Selected Papers (1963).
Throughout his long career Cross received frequent accolades. Hampden-Sydney awarded him an honorary doctorate of science in 1934, and three years later he received an honorary M.A. from Yale and an honorary doctorate of engineering from Lehigh University. In 1936 the American Concrete Institute awarded Cross its Wason Medal for Most Meritorious Paper. He became a fellow of the American Academy of Arts and Sciences in 1945, and the American Society of Civil Engineers granted him honorary membership in 1947. A few months before his death Cross received the Gold Medal of the British Institution of Structural Engineers. In 1959 the Franklin Institute posthumously awarded him its Frank P. Brown Medal for his contributions to engineering education and the profession.
Cross retired from Yale in 1953 and moved to Virginia Beach. Despite poor health he continued to consult with engineering firms. Hardy Cross died at his Virginia Beach residence on 11 February 1959 and was buried in Ivy Hill Cemetery, in Smithfield. The Norfolk branch of the American Society of Civil Engineers named its Hall of Fame for Cross, and the Virginia section of the ASCE established the Hardy Cross Memorial Award for the best paper presented by an engineering student.
Sources Consulted:
Biographies in Who's Who in Engineering (1954), 535 (with birth and marriage dates), and Leonard K. Eaton, Hardy Cross: American Engineer (2005), with several portraits; variant birth year of 1884 in Birth Register, Nansemond Co., Bureau of Vital Statistics, Commonwealth of Virginia Department of Health, Record Group 36, Library of Virginia; marriage license recorded in Washington Post, 3 Sept. 1921; Hardy Cross Papers, University of Illinois at Urbana-Champaign; Engineering News-Record, 13 July 1944, 20 Nov. 1958; Civil Engineering 18 (1948): 37; ibid. 29 (1959): 892; Norfolk Virginian-Pilot, 16 June 1995; obituaries in New York Times, Norfolk Ledger-Dispatch and Portsmouth Star, Norfolk Virginian-Pilot, and Washington Post and Times Herald, all 12 Feb. 1959, Engineering News-Record (19 Feb. 1959), 28, Civil Engineering 29 (1959): 193, and Virginia Engineer 9 (spring 1959): 31; editorial tribute in Norfolk Virginian-Pilot, 13 Feb. 1959.