EFFECT OF THE COUPLING OF MOTION ON THE PERFORMANCE OF MACHINE FOUNDATION

Abstract

Machine foundations, subjected to dynamic loading vibrate in different modes. Sometimes, these different modes of vibration are coupled either due to an error in placing of the machine on the foundation or due to interactions with the other foundations lying nearby. This phenomenon of coupling of motions in machine foundations affects their responses, because of the interaction between the waves propagating through the soil-medium. The properties of waves in the soil-medium are functions of various parameters viz., type and properties of soil, layering of soil-medium etc. The frequency and amplitude of vibration of machine foundation due to coupled motion is caused by an eccentric loading and interaction with other foundations. For the study of the coupling of motion between machine foundations ANSYS software has been used which employs the finite element procedure for analysis. The capabilities and the limitations of the computer package in analysing such problem have been discussed. The effect of coupling of motion due to an eccentric loading has been studied by performing experiments also. The block vibration tests on a concrete block of size 2.25m x 0.75m x 0.70m has been done by placing the oscillator at the centre as well as at an eccentric point. The same block has also been analysed by ANSYS package. The comparison of results obtained from the two methods leads to some important concluding remarks.