Dynamic Centrifuge Model Tests on Plate-Shaped Building Supported by Pile Foundation on Thin Load-Bearing Stratum Overlying Soft Clay Layer

Abstract

AbstractIn Japan, many plate-shaped buildings are built as residences in coastal areas. As a result, some of them are sustained by the pile foundation embedded on the thin load-bearing stratum overlying the soft clay layer because a continuous load-bearing stratum is too deep to construct economically. During a large earthquake, plate-shaped buildings cause large lateral force and varying axial force in their pile foundations and make their seismic behavior more complicated because they each have a high aspect ratio and single-span composed of two columns and several beams. In addition, the thin load-bearing stratum overlying soft clay layer makes the seismic behavior of a plate-shaped building more complex because of the less stiffness of soft clay. In this study, two dynamic centrifuge model tests in a 50 g field were carried out to compare the seismic behavior of the plate-shaped building and pile foundation on the thin load-bearing stratum overlying soft clay layer with that on the continuous load-bearing stratum. From the several shaking tests, it was observed that the large instantaneous acceleration of the superstructure occurred when the gap between the pile tip and the load-bearing stratum was closed in the model on the continuous load-bearing stratum. On the other hand, the bending moment at the pile head in the thin load-bearing stratum was almost equal even though the inertial force differed. However, the pile foundation on the thin load-bearing stratum did not settle critically, although the peak axial force was almost double the preload.KeywordsThin load-bearing stratumPile foundationPlate-shaped buildingCentrifuge motel testSeismic behavior