When connected piles are used as settlement reducers, the proportion of vertical load carried by the pile may come close to the allowable load of the pile. To reduce not only the vertical load, but also the lateral load and bending moment to which the pile is subjected, the disconnected piled raft (DPR) has been introduced as an effective design for the role of the settlement reducers. Although several DPRs have been constructed, most of the research efforts on DPRs are limited to the structural behavior such as the evaluation of the seismic acceleration of the structure on the DPR; thus, there is a need to evaluate the dynamic performance of DPRs focusing on geotechnical problems. In this study, the seismic behavior of DPRs is investigated using dynamic centrifuge tests and compared with the results obtained from connected piled rafts (CPRs). The bending moment of piles of different materials, namely aluminum and steel, is evaluated. Results show that there is a reduction in the amplitude of acceleration of the foundation horizontal motion for the DPR compared to the CPR. The edge pile of a DPR attracts the smaller dynamic bending moment of the pile compared to that of a CPR. The dynamic bending moment of piles is predominantly governed by the soil behavior rather than the pile material. Finally, the seismic behavior of DPR was evaluated comprehensively through centrifuge tests.

The rocking behavior of a shallow foundation of a bridge pier has emerged as an effective mechanism for reducing the seismic load on the superstructure during a strong earthquake. However, a lack of understanding regarding the rocking behavior of shallow foundations has hindered the application of the rocking foundation design philosophy to construction. In this study, the soil-rounding effect on embedded foundations was evaluated to increase understanding of the rocking mechanism. A centrifuge apparatus was used to conduct horizontal slow cyclic tests on an embedded shallow foundation model for three different slenderness ratios (i.e., structure height divided by foundation length) at a centrifugal acceleration of 20 g. The soil-rounding phenomenon was examined according to variations in the soil pressure under the foundation during cyclic loading, and the shape of the rounded soil surface was evaluated as a function of the slenderness ratio. The ultimate moment capacity of the shallow foundation was observed to increase with the side soil pressure; this was verified by comparing the side soil earth pressure with the overturning moment. The rocking mechanism of the embedded shallow foundation was evaluated by focusing on soil rounding.