Takenori Hida

Pile Stress Estimation Based on Seismic Deformation Method with Embedment Effects on Pile Caps

A pseudostatic analysis, based on the beam on nonlinear Winkler-spring method considering the seismic earth pressure and side friction acting on embedded pile caps, was developed to estimate pile bending moments and shear forces. To verify the proposed method’s effectiveness, the authors conducted six dynamic centrifuge tests on a superstructure-footing model supported by 2×2 piles in sand deposits comprising a dry sand layer over liquefied soil. The seismic earth pressure, vertical wall friction at the active and passive sides, and friction at the sidewalls of the pile caps were separately measured by two-dimensional load cells during shaking. The seismic total earth thrust and side friction estimated by the proposed method showed good agreement with the experimental results for both the amplitude and phase difference to the superstructure and the pile cap inertia forces. The estimated bending moment and shear force in the piles also showed reasonable agreement with the experimental results; they were able to account for differences in the pile rigidity and soil relative density.

DAMAGE ESTIMATION OF A SUPER HIGH-RISE RESIDENTIAL BUILDING DURING THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE AND ITS RESIDUAL SEISMIC PERFORMANCE

During the 2011 off the Pacific Coast of Tohoku earthquake, most super high-rise RC buildings constructed in the metropolitan area had suffered severe shaking, leading to variation of dynamic properties due to structural damages. This study describes the damage estimation of the super high-rise RC building during the main shock using the 3D frame model. Their varying dynamic characteristics are discussed based on the system identification method. The dynamic properties during aftershocks are also investigated in view of the residual seismic performance after experiencing moderate-level structural damages.