ANALYSIS OF MACHINE FOUNDATION UNDER BLAST LOADING

Abstract

Structures all over the world are increasingly being exposed to the threat of premeditated explosive attacks, accidental explosions and other forms of explosion related failures. The magnitude of blast loads produced by most explosions are significantly higher than the design loads for conventional structural design. Due to this, there can be adverse effect on within and nearby the affected structure. Foundations supporting hammers, presses and mills are subjected to harmonic excitations during normal operation. During operational phase of machines if any accidental blast occurs, entire system is affected and it varies with the magnitude and distance of the blast. The planning of foundations for equipment sensitive to vibrations requires a thorough dynamic investigation of the proposed location of the foundation with regard to the effect of already existing or additional vibration sources and blast loading. The design of a machine foundations should be such that they will neither endanger the satisfactory operation of the machine nor will they disturb the people working in the immediate vicinity. This report focuses mainly on assessing the dynamic behaviour of machine foundation under the combined effect of rectangular pulse loading and accidental blast loading for different possible cases on the basis of pulse duration and blast duration. For this, the hammer foundation system has been considered as SDOF system and it has been assumed that the machine is in operating condition i.e., blast load does not cause direct physical damage to machine. Analysis will be done for different possible cases of equation of motion to obtain the response of hammer foundation system. Finally, the solution has been obtained analytically and by the numerical method for the response of SDOF system and then parametric study have been done to analyse the influence of different parameters on response of SDOF system.