Damping in Torsional Vibrations of Embedded Footings

The existing theoretical models to explain the dynamic behavior of embedded footings, overestimate the real response by neglecting damping forces which are inevitable as a result of slip at the interface of the embedded footing and soil. Many researchers in the field of Soil Dynamics have suggested that the inclusion of friction damping and internal damping in the mathematical model is necessary to improve the reliability of theoretical predictions. In this paper, results of the experimental investigations on full scale model embedded footings subjected to torsional mode of vibration have been presented. The results have been analyzed making use of three theoretical models, as developed by, Novak and Sachs (1973); Sankaran et al (1978) and Sankaran et al (1980). The importance of d-ping in predicting the dynamic response is brought out by a comparison of field vibratory test data with the corresponding values predicted by each of the above mentioned theoretical models