Seismic Analysis of Pile Foundations Damaged in the January 17, 1995 South-Hyogo Earthquake by Using the Seismic Deformation Method

With respect to the South-Hyogo Earthquake of January 17, 1995, a lot of research results have been published including many studies on the damage to pile foundations resulting from liquefaction as well as consequent lateral flow of surface ground (Mori et al, 2000 and Horikoshi et al, 2000). However, reports concerning seismic analyses of foundations damaged by non-liquefaction causes, such as ground shaking, are still rare. Actually, studies on non-liquefaction damage are also important because this kind of damage may occur in a more extensive scope than the liquefaction damage may. This paper summarizes a seismic analysis of a pile foundation damaged by ground shaking induced by the quake. The method used for the analysis is so-called Seismic Deformation Method (SDM) that is stipulated in a new design code called Seismic Design Code for Railway Structures (the Railway Code, 1999, in Japanese). The seismic analysis was conducted in the procedure as: a) response analysis of the damaged pile foundation; b) assessing seismic performance of the foundation; c) comparison of the results obtained from the analysis and the in-situ damage investigation. As the results, the adequacy of SDM was confirmed by the good agreement between the analysis and investigation. Moreover, the damage mechanism of the foundation was elucidated based on the data from analysis and investigatio