Shaking table tests on model piled rafts in sand considering influence of superstructures

A series of shaking table tests were carried out on model piled rafts in dry Toyoura sand using a shaking table at 1-g field. Two experimental variables were considered, i.e. frequency of input acceleration and height of the centre of gravity of superstructure, while keeping the mass of superstructure constant. This paper provides experimental results of piled rafts having a rigid connection condition between the raft and the pile heads, and compares them with the results obtained from the static horizontal load tests of the same models, which have been carried out by Matsumoto et al. (2004). Principal findings from the present study are 1) Resonant frequency of superstructure decreases as height of its centre of gravity increases, as expected; 2) At input frequency lower than the resonant frequency, the behaviours of the piled rafts subjected to shaking are close to those obtained from static horizontal loading tests; 3) Even if the horizontal acceleration responses at the centres of gravity are the same, inclination of the raft, shear forces and bending moments of the piles increase as height of the centre of gravity of the superstructure increases.