State the Planning the foundation for reciprocating engines
i) The eccentricity of the common centre of gravity of machine and foundation referred to the centroid of base area should not exceed 5% of the corresponding base dimension of the foundation.
ii) To decrease the transmission of vibrations to adjacent structures, it is necessary to provide an air gap around the foundation. Where the elastic under layers such as spring casings are provided below the foundation, the latter should be placed in a reinforced concrete trough and due provision made to give access to the under lying layers for periodical inspection of replacement.
iii) In order to reduce the horizontal amplitudes, the height of foundation should be selected as small as possible. A larger base dimension is selected in the direction of the rock moment if any, acting on the foundation.
iv) If several machines are located close-by in the same machine hall, a common foundation may be recommended for all of the machines, particularly when the underlying soil is soft. However, the analysis of vibrations of the foundation for such a group of machines, is complicated. For practical purposes, the common foundation may be considered as broken up to sections corresponding to individual foundations and the computations carried out as if they were separate foundations. The permissible amplitudes may be increased to 0.25 mm.