Dynamic Analysis of Block-Type Machine Foundation Using Barkan’s Model for Various Soil Parameters

Abstract

Machine foundation involves both the static loads and the dynamic loads caused by working of the machine. The machine weighs several tons and is required to restrict amplitudes to only a few microns. Inadequately constructed foundations may result in failures exceeding many times the cost of the capital investment required for properly designed foundations. This necessitated a deeper scientific investigation of dynamic loading and analysis. Method proposed by Barkan (recommended by IS: 2974-1982) for design of machine foundations under harmonic load, still remains the most popular method for vibration analysis of block foundations in Indian industry. Finite Element (FE) is very commonly accepted analysis tool for solution of engineering problems. Effective Pre and Post-processing capabilities make modeling and result interpretation simple. The current paper aims to do the parametric study of dynamic analysis of block foundation using Barkan’s method. For the same, three different machines of 150 rpm, 250 rpm and 450 rpm are taken into account and six different soil types: (a) Medium, Stiff and Hard Clay and (b) Loose, Medium and Dense Sand are considered. Foundation sizes are optimized according to soil cases and each case is analysed using conventional method and FEM model using STAAD Pro. for 0.8, 1 and 1.2 times the soil parameters to cover the confidence range. This study is further extended for the comparison of concrete quantity consumed. The results grossly show that as the clay varies from medium to hard, and sand from loose to dense, the foundation size required, decreases. It was seen that, with the increase in stiffness of soil, natural frequency of machine foundation soil system increases and amplitude of foundation reduces. Also, FEM method of analysis indicates safer amplitude of foundation compared to classical method of analysis, inferring to conventional method being conservative.