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The American bridge (it was also referred to as The Howe Bridges, or Nikolaev railway bridge until December 31, 2008) — is essentially a group of railway bridges that connect the Bezymyannyi island (St. Petersburg) to the left bank of the Neva River via the Obvodny Canal, and provide links between the Central and Nevsky districts of the city of Saint Petersburg. == History == The wooden bridges of the same design as now were constructed over the period 1840-1850 during the construction of the Nikolayevskaya Railway. The main construction works were supervised by the prominent American railroad engineer George W. Whistler to a design by William Howe, an American bridge builder and inventor. The essence of the construction project was that the bridge's spans were expected to be a truss system of bracing wood design constricted by cross iron bars (this was the very novelty). Due to the presence of the metal parts, the bridge structure became much stronger without substantial increases in overall weight. The William Howe's system was theoretically checked and then improved by the Russian engineer Dmitrii Juravsky, who was an executive assistant to George W. Whistler during the construction of the railway line. Juravsky performed structural analyses and tests on physical models of Howe trusses from 1843 to 1848, and executed studies of the effect of posttension in Howe trusses. He published two books “About Bridges of the Howe System” in 1855 and 1856.〔(The Howe Bridges on the Nikolayev Railway by. Kamil Nizamiev and Dario Gasparini, PhD. Case Western Reserve University. - P.46-47 )〕 Juravsky was able to prove that the closer to the bridge pillars, the greater the strain on the vertical tension bars and diagonal braces. So, he proposed to make the truss members of varying thickness depending on a specific location. His ideas were endorsed by Whistler, and then used in the construction of other rail bridges on the road. As the road was built in the forward direction, it was necessary to build 278 artificial structures. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「The American Bridge」の詳細全文を読む スポンサード リンク
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