M.R MAHERI - Department of Civil Engineering, Shiraz University, Shiraz, Iran

The classical added-mass solution of structure-fluid dynamic interaction is an approximate solution producing erroneous results for higher-order modes. In this paper an accurate, modified added-mass approach has been proposed. The method is based on the results of dynamic tests in which the distribution and amount of added-mass in pure modal vibration were measured. Experimental findings, supported by theory, indicate that the modal added-mass is the same as the classical added-mass for rigid vibration, but only a fraction of it participates in the modal vibration of higher modes. The modal participation factors are found to provide a good measure for the active added-mass in higher order modes. The accuracy of the proposed modified added-mass approach is checked against the more elaborate Eulerian and Lagrangian solutions for a typical dam-reservoir system.