ANALYSIS OF RECIPROCATING MACHINE FOUNDATIONS RESTING ON PILES

Abstract

Machine foundations are generally classified as special foundations. They require a detailed analysis of the foundation response to the dynamic load coming from the anticipated operation of the machines. Reciprocating Machines includes engines and compressors with operating speed varying from 50 to 1000 rpm. The reciprocating machines are normally founded on blocks. Under unavoidable situations the reciprocating machines are founded on piles. Reciprocating machines resting on piles are analyzed with the help of solutions arrived from dynamic behavior of pile groups. The basic equations to study the dynamic behavior of piles and pile groups were developed' by Novak. The solution given by Novak was complicated since it involves several constants. An attempt is made to simplify the procedure used to analyze the pile group subjected to dynamic load. A machine foundation resting on pile group problem is selected such that the parameters used resemble the actual field conditions and analyzed for the dynamic conditions. To simplify the problem certain assumptions are made. MATLAB programs were developed for different modes of vibration and the machine foundation system was analyzed for varying parameters and hence the variation in the natural frequency and amplitude of the system were studied. The pile group system was also compared to the equivalent block foundation system to study the frequency and amplitude variation of both the systems. The results obtained from the MATLAB programs were cross checked by manual calculations and charts were prepared to depict the variation of natural frequency and amplitude for different modes of vibration.