Hans Bleich

Hans, the son of Friedrich Bleich, was awarded a diploma in structural engineering by Vienna TH in 1931 and three years later gained his doctorate at the same university. During his student days, he contributed a chapter to the book Die gewöhnlichen und partiellen Differenzengleichungen der Baustatik, which was published by his father and Ernst Melan in 1927. So in terms of his career he followed in the footsteps of his father. In 1932 Bleich drew attention to himself with a revolutionary publication in which the principle for the shake-down of steel structures was formulated for the first time, and which Ernst Melan generalised for structures in bending in 1938. Shake-down occurs when the plastic dissipation work remains limited in all parts of a loadbearing structure under the action of alternating loads. The Bleich-Melan shake-down principle forms an important cornerstone of plastic theory. Up until 1939, Bleich worked as an engineer for the Vienna based contractor A. Porr AG and, following his emigration in that same year, for Braithwaite & Co. Ltd. in London. He started a new life in the USA in 1945 and it was there that he was able to develop his talents as both structural engineer and scientist ideally – as a research engineer at Chance-Vaught Aircraft in Stratford, and as a bridges engineer at Hardesty & Hanover in New York. From 1957 until his death he was active as a consultant for Weidlinger Associates in New York, where he played a major role in the conception, design and analysis of innovative structural systems for high-rise buildings, exhibition buildings and special structures like the Mount Wilson Observatory. It was in 1947 that he began teaching and researching at Columbia University, initially in the field of structural engineering, later aircraft construction (he became director of the Guggenheim Institute of Air Flight Structures in 1954). He resigned from his Alma Mater in 1975 as professor of structural engineering. He worked on and edited his father’s book Buckling Strength of Metal Structures, which appeared two years after the latter’s death. In total, Bleich published 68 papers and reports on theory of structures and applied mechanics. “His technical reports dealt with the gamut of those applied mechanics problems that are of practical significance in the field of dynamics and, particularly, in the interactions between fluids and elastic and plastic bodies [Salvadori, 1989, p.47 ]. Understandably, he made major contributions to important technical directives such as the ASCE manual Design of Cylindrical Shell Roofs (1952), the Guide for the Analysis of Ship Structures (1960) published by the US Department of Commerce, and the report entitled Support and Testing of Astronomical Mirrors (1968) published by the Kitt Peak National Observatory in Arizona. His amazingly successful creativity was rewarded by renowned associations and societies, the ASCE Kármán Medal being just one example.

Main contributions to structural analysis:

Über die Bemessung statisch unbestimmter Stahltragwerke unter Berücksichtigung des elastischplastischen Verhaltens des Baustoffes [1932]; Die Berechnung verankerter Hängebrücken [1935]

Source: Kurrer, Karl-Eugen The History of the Theory of Structures, Wilhelm Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH, Berlin (Deutschland), ISBN 3-433-01838-3, 2008; p. 718