DHARMELEMENTS OF SOIL DYNAMICS AND MACHINE FOUNDATIONS 875
- Richart, F.E.Jr., Hall, J.R.Jr., and Woods, R.D.,: Vibrations of Soils and Foundations of Soils
and Foundations”, Prentice Hall, Englewood Cliffs, NJ, USA, 1970. - Richart, F.E. Jr. and Whitman, R.V.: “Comparison of Footing Vibration Tests with Theory”,
Journal of SMFE, Proc., ASCE, Vol. 93, No. SM6, pp. 143-168, Nov., 1967. - Sadovsky, M: “Zweidimensionale Problems der Elasticitats theorie”, Z. Angew, Math, and Mech.,
Ed. 5, 1928. - Sankaran, K.S. and Subrahmanyam, M.S.: “Calculated and Observed Vibration Amplitudes”,
Discussion, Journal of SMFE, Proc. ASCE, Vol. 97, 1971. - Srinivasulu, P and Vaidyanathan, C.V.: “Handbook of Machine Foundations”, Tata McGraw Hill
Co., Ltd., New Delhi, 1976. - Subrahmanyam, M.S.: “Prediction of Vertical Vibrations of Footings”, Ph.D. Thesis submitted to
the IIT, Madras, 1971. - Sung, T.Y.: “Dynamic Testing of Soils: Vibrations in Semi-infinite Solids Due to Periodic Surface
Loading”, (Symposium), Special Publication No. 156, ASTM, 1953.
QUESTIONS AND PROBLEMS
20.1 Define the following with respect to machine foundations:
(a) Degree of freedom (b) Simple Harmonic motion
(c) Free Vibration and forced vibration (d) Frequency
(e) Amplitude (f) Resonance.
20.2 Explain the different modes of vibration of a foundation block subject to dynamic forces from a
machine.
20.3 Explain the term ‘Damping’ and give the characteristics of different types of damping.
20.4 Explain what is meant by ‘Natural Frequency’ of a foundation-soil system.
20.5 Explain ‘Frequency Ratio’, Magnification factor’ and ‘Damping Factor’.
20.6 Explain ‘Free Vibration with damping’ and bring out the meaning of overdamped, underdamped,
and critically damped conditions.
20.7 Explain ‘Logarithmic Decrement’.
20.8 Distinguish between constant force type and quadratic type of Excitation.
20.9 Explain the ‘tolerance limits of amplitudes’ as given by Richart and by Barkan.
20.10 Explain the different types of waves that propagate through soil.
20.11 Explain (a) Coefficient of elastic uniform compression
(b) Coefficient of elastic uniform shear.
20.12 Describe the ‘Repeated Plate bearing Test’ used for the determination of the coefficient of elastic
uniform compression.
20.13 Explain how the coefficient of elastic uniform compression varies with the size of the plate or
foundation.
20.14 Describe the ‘Standard Block Vibration Test’ for the determination of in-situ dynamic properties
of soil.
20.15 What are various types of machine foundations used for different kinds of machinery? Give neat
sketches.
20.16 Explain the general criteria for the design of machine foundations.