A mechanical model describing the planar elasto-dynamics of arch bridges with general arch profiles is presented. The model is amenable to analytical or semi-analytical treatments and is effective for parametric studies, design of control systems or structural optimizations. The Ritz's energy approach is employed to calculate the solutions of the vibration eigenvalue problem-natural frequencies and mode shapes-and the forced responses to external excitations, namely those induced by the passage of trains. A closed-form solution of the bridge dynamic response to the transit of trains with arbitrary load distributions and running speeds is found and the train-induced resonances are accordingly discussed. In particular, three European high-speed trains-the French TGV, the Italian ETR 500, and the German ICE-traversing a lower-deck steel arch bridge are considered and the ensuing responses are investigated. (C) 2007 Elsevier Ltd. All rights reserved.
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