Author(s): E. Naudascher; H.-J. Medlarz

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Abstract: Both the hydrodynamic force acting on a bridge submerged in open-channel flow and the head loss associated with this channel obstruction are being expressed in terms of a force coefficient and treated theoretically as well as experimentally. The results of systematic force measurements are plotted in the form of resistance diagrams to show the effects of all relevant geometric parameters and the Froude number in the most generalized way. For increasing Froude number, the flow is shown to change from a submerged condition to free flow, detaching from the upstream-most girder like from a sluice gate. The force coefficient for this particular case is predicted with the aid of momentum and energy equations. It is suggested that this value be used to estimate the peak loading acting on the submerged bridge due to wave motion between the girders induced by flow instability and vortex formation. The paper concludes with a practical example in which the results of this study are applied to a particular case of bridge submergence.

DOI: https://doi.org/10.1080/00221688309499416

Year: 1983