Three-Dimensional Dynamic Behavior of Embankment on Liquefiable Ground

In recent years, there has been serious damage to embankments on liquefied ground because of large earthquakes. To understand such damage, many two-dimensional shaking table model tests have been performed, in both gravitational and centrifugal fields, to investigate the dynamic behavior and residual displacement of embankments and river dikes on liquefiable ground. In recent years, three-dimensional numerical analysis has been used in practical design because it is difficult to consider the complex dynamic behaviors of three-dimensional embankments and the surrounding liquefied ground in a two-dimensional analysis. However, there are only a limited number of cases in which the applicability of three-dimensional analysis has been validated based on comparisons with true values derived from model tests or data from actual disasters. Therefore, in this study, a series of shaking table tests were conducted to investigate the seismic behavior of a three-dimensional embankment on liquefiable ground. In addition, the effect of the shaking direction on the seismic behavior of the embankment was evaluated. The experiment revealed that the residual deformation and its dominant direction were significantly affected by the three-dimensional shape and total weight of the embankment, not by the shaking direction. This result indicates that the influence of the three-dimensional shape of the embankment on the deformation behavior cannot be ignored, and that the influence should be properly evaluated in seismic design.

Seismic behavior of hybrid coupled shear wall with replaceable U-shape steel coupling beam using terrestrial laser scanning

The hybrid coupled shear wall (HCW) with replaceable coupling beam (CB) is an optimal component to recover buildings promptly after a severe earthquake. However, the reinstallation may be difficult or impossible with an identical CB because of the inelastic relative dislocation between two wall piers. This study proposes a novel HCW with different reinforcement ratios in the connection, which was tested under cyclic loading. After the test, the bolt holes can be located through terrestrial scanning, which is then utilized to fabricate a new CB that can accommodate the deformation between two wall piers. The newly replaced HCW system was also tested. As a result, all virgin test specimens fail in web fracture and show a significant inelastic chord rotation of 0.2 rad, exhibiting an excellent energy dissipation capacity. Meanwhile, the new method to locate the bolt holes after the test is feasible. The replaced HCW fails in the pull-off of anchor bars and shows poor seismic behavior due to the unpatched concrete cover in the connection. To improve the energy dissipation for the replaced HCW, high-strength grouting in the connection can be used and high-strength material can be used to replace the usual anchor bolts.