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INTRODUCTION
Foundation are generally subjected to static loads but dynamic load ,at time pose great threat to the stability of foundation.
The static load is the one which is imposed slowly and gradually but on the other hand the dynamic load is the one which is applied rapidly and repeatedly.
Earthquake is the greatest example of dynamic load producing event.
How ever machine foundation are regularly and inevitably subjected to dynamic load.
The dynamic load is generally understood as a vibratory force and represented by amplitude, frequency ,and time period.
In some cases , the foundation are subjected to dynamic loads.These loads may result from various causes such as vibratory motion of machines , movement of vehicles, impact of hammers ,earthquake, winds , waves , nuclear blasts, mine explosions and pile driving.
The dynamic loads transmitted to the foundations and their effect on the strata below can be determined using the principle of soil dynamics and principle of vibrations.The analysis is how ever very complex.
MACHINE FOUNDATION
Machine foundations are subjected to the dynamic forces caused by the machine.These dynamic forces are transmitted to the foundation supporting the machine.
Althrough the moving parts of machine are generally balanced,there is always some unbalance in pratice which causes an eccentricity of rotating parts.
This produce an oscillating force.
Machine foundation satisfy the criteria for dynamic loading in addition to that of static loading.