Damage done to civil structures by the 2000 Tottori-ken Seibu Earthquake was investigated. Field surveys were made from October 8-10 by eight members dispatched by the JSCE in cooperation with other researchers. Descriptions are given of the earthquake, seismic ground motion; the damage done to such civil structures as roads, road bridges, lifelines, dams, port facilities; slope failures; and public risk management. Although peak ground accelerations were extremely intensive, structural damage was not as severe as compared with the average damage caused by past earthquakes in Japan. Such disaster responses as search and rescue activities, emergency responses, disaster information communication, and victim supports are discussed.

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This paper aims to propose a criterion in terms of equivalent plastic strain or axial strain against ductile crack initiation for structural steels. For this purpose, tension test on round steel bars is simulated by finite element method and strain progression during the necking process until ductile crack initiation is investigated. Due to very large strain involved in this simulation, the common used constitutive model for structural steels is modified, and the Gurson's micro void model is employed to consider the material deterioration. As a result, a prediction criterion for structural steels is put forward in terms of stress and equivalent plastic strain. Moreover, a relation between local strain and global strain is obtained and ultimate strains are proposed to evaluate ductile crack initiation for fiber analysis of steel structures in seismic design.

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In the seismic design codes for railway structures, a deformation capacity of RC piles is evaluated based on the experimental results, which have been obtained from alternate loading tests of RC columns under the atmospheric conditions. The actual behavior of piles, however, is likely to show a greater degree of ductility than these experimental results, because piles embedded in the ground are subject to confining pressure from the subgrade. In this study, we aimed to establish a rational evaluation method of seismic performance of pile foundations. A calculation method of ductility of RC piles is proposed, in which confining pressure by the subgrade reaction is converted into an equivalent passive confinement pressure from hoop reinforcements.
 We have conducted alternate loading tests of RC columns supported by coil springs instead of the ground. We confirmed the applicability of the newly developed method by comparing these experimental results with numerical simulation results. In addition, we calculated the seismic response of railway structures with general shape and size using the proposed model, and confirmed the applicability of the proposed model to railway structures.

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In the design practice of retaining walls which support road embankments, stability under the action of strong earthquake ground motion is usually not examined. However, collapse of road embankments in mountainous area often results in cutting off road traffic and complete isolation of people in the neighborhood for a long time. The author surveyed a number of damaged and undamaged road embankments in the mountainous area where strong ground motions were recorded during the 2004 Niigataken-Chuetsu Earthquake. It was revealed that catas trophic failure of embankments constructed on sloping foundation soils were in many cases triggered by damage of retaining walls and most of such damaged retaining walls failed in the mechanism of the bearing capacity failure of the foundation soil. In this study a simple method to examine the seismic stability of existing retaining walls is developed, which evaluates a factor of safety for the bearing capacity failure of foundation on slope under combined loading in conjunction with soil strength parameters obtained by dynamic cone penetration tests using a portable testing device. A good correlation was found between the factor of safety of the surveyed walls derived from the method and the observed deformation of the walls, confirming the effectiveness of the method to identify seismically unstable walls out of existing walls.

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We developed a model for evaluating the effects of functional impairment of road networks due to seismic damage, based on the data from the 1995 Hyogo-ken Nambu Earthquake. The effects of functional impairment of road networks on various sectors were analyzed to clarify the relationship between functional impairment of road networks due to a seismic event and seismic damage to road networks. Functional impairment due to seismic structural damage to road networks was modeled as a functional impairment matrix. Combining the model of seismic damage effects with the functional impairment matrix, we assessed the cost of the functional impairment associated with the Hanshin Expressway Route 3.

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The Mid Niigata Prefecture Earthquake of 2004 was an inland earthquake characterized by damage focused in local and mountainous areas. The damage of road infrastructures is also marked by the characteristics of the local area. In order to prevent or reduce earthquake damage in the future, it is important to clarify the characteristics of the damage level and the road traffic performance in the local and mountainous area, and reflect them in future earthquake prevention measures.
This paper highlights the damage of road embankments and discusses the effects of road closures on local societies, based on related documents and field investigations. The study also quantitatively estimates the damage levels of road infrastructures, road traffic performances in the local and mountainous areas and the relationships between the seismic intensity scale and both damage level and road traffic performance. From these evaluations, new lessons for future earthquake prevention measures have been obtained.

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