DYNAMIC RESPONSE OF STRUCTURES ON PILES

Abstract

The analysis of the response of structures supported on flexible pile foundations, subjected to dynamic loads, involves the problem of interaction between soil, pile and superstructure systems. Vari ous authors have proposed methods for the analysis of such systems. These methods, involve tedious mathematical operations and requires elaborate field testing arrange-ments, and are therefore not suited for the day to-day design problems. In the work reported here-in, an attempt has been made to evolve a simple method to analyse the response of such systems under dynamic lateral loads. The complex system has been assumed to be represented by an equivalent two degree freedom system. The soil and pile have been assumed to be represented by a single degree freedom system, which is coupled to an another single degree freedom system, representing the super-s tructure. The effect of various parameters, that is, natural frequency of foundation,, natural frequency of Super-structure and the mass ratio between the super-structure and foundation systems on the response of system,, when exited by earthquake motion has been IV theoretically analysed. Experimental studies have also been conducted by mounting a single degree mass spring system, on an aluminium pile head, enbedded in sand. The response of the system hasbeen actually observed by giving it Sinusoidally varying vibrations. The above model has been theoretically analysed4 by experimentally evaluating the various constants for it. The results obtained by e)p eriment al observations and those obtained by theoretical analysis compares well.