To understand the seismic performance of a disconnected piled raft (DPR) foundation during strong earthquakes, dynamic centrifuge tests were conducted on a soil–foundation–superstructure system. The bending moment of piles in the DPR includes both dynamic and static components during a strong earthquake. The static component of the bending moment is caused by the cyclic one-sided lateral load from the overturning moment. The dynamic component, which can be estimated through seismic pile design, is approximately half of the actual bending moment. When evaluating the pile stress of the DPR for buildings with a high aspect ratio, care should be taken not to underestimate the bending moment during strong earthquakes as the overturning moment tends to be large and is prone to cyclic one-sided lateral loads. The sum of the maximum compressive axial loads of conventional pile foundations (PF) was 1.8 times the weight of the structure. The high axial load in the PF resulted from the piles in the back and middle rows bearing tension forces. The maximum compressive axial load of the piles in the DPR was 55% of that in the PF. The DPR piles did not bear tensile loads. Therefore, when the raft was uplifted, the sum of the compressive axial loads on the front piles of the DPR did not exceed the weight of the structure. • Disconnected piled raft foundation vs conventional pile foundation. • Small axial load of the piles during earthquake in DPR. • Cyclic one-sided lateral load caused by overturning moment. • Static bending moment of piles caused by cyclic one-sided lateral load. • Residual deformation of piles after strong earthquake.
Tamura et al. (Fri,) studied this question.