ROEBLING

GERMANY (see also List of Individuals)

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12.6.1806 Mühlhausen/D - 22.7.1869 Brooklyn NY/USA

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John (Johann) Roebling graduated in 1826 as a civil engineer from the Berlin Polytechnic. He stayed for three years with the Prussian Corps of Engineers to emigrate in 1829 to the USA. He first was in charge of river works, then contributed to railways projects and in 1841 manufactured the first transversely wrapped wire cable in the USA. In 1845 he designed a suspended aqueduct in Pittsburg and the first suspension bridge in 1846. He completed in 1850 the famous suspension bridge at Niagara Falls.

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Early suspension bridges built before 1840 were light, flexible structures at the mercy of the wind. One of the earliest chain spans was the Dryburgh Abbey Bridge across the Tweed in Scotland. The 80 m long bridge erected in 1817 was completely destroyed by a gale. The famous Menai Straits Bridge in Wales with a record span of 180 m built by Thomas Telford in 1826 was the subject of alarming aerodynamic vibrations. The first Niagara-Clifton Bridge at Niagara Falls had a record span of 400 m and was taken into service in 1868; rebuilt in 1888 it was completely destroyed by wind action shortly later. It was realized in the 1830s in France that troops crossing a suspension bridge must break the step because the bridge fail by the cumulative amplification of vibrations. These lessons were forgotten by 1940 when the 870 m long Tacoma Narrows Bridge, then the world's third longest structure, failed shortly after erection. The only engineer around 1850 who grasped the full significance of the problems appears to have been Roebling. With his intuitive genius, he realized the need of bracing and stiffening suspension spans against the cumulative vibrations set up by wind. In his pioneering article in the American Railroad Journal of 1841, he discussed the weaknesses of earlier suspension bridges and measures to insure the safety of future spans. He is considered the father of aerodynamic design in engineering.

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_{Anonymous (1972). Roebling, John Augustus. A biographical dictionary of American civil engineers: 103-104. ASCE: New York.}

_{Fitzsimons, N. (1966). Who am I: John A. Roebling. Civil Engineering 36(3): 92. P}

_{Roebling, J.A. (1831). Diary from my journey from Muehlhausen to the USA in 1831. Trenton. Sayenga, D. (1995). Pittsburg aquaduct: Reconstruction of the Pittsburgh aqueduct by John A. Roebling. Canal History and Technology 14: 73-90. P}

_{Steinmann, D.B. (1945). Design of bridges against wind. Civil Engineering 15(11): 501-504. P}

_{Tillmann, F. (1941). Johann August Roebling, ein Bahnbrecher im Bau der Hängebrücken. Bautechnik 19(52): 553-554. P}