Dynamic characteristics of a composite foundation of wall and pile group are investigated using the results of forced vibration test and earthquake observation. It is clarified that the interior piles show similar vibration mode to that of the wall foundation, and the existence of basement and interior piles restrict the natural vibration of the interior soil. The analytical results using an axisymmetric FEM show the shear force during earthquake is largely burdened by the wall foundation and that is large at the deep part of the soil. The effectiveness of the simplified lumped-mass model is verified through earthquake response analyses.
