The Role of Soil on the Collapse of 18 Piers of the Hanshin Expressway in the Kobe Earthquake

Cuny City University Of New York, New York NY

Investigators

Abstract

0000101 Mylonakis The object of this research is to improve the understanding of the effect of soil-structure-interaction (SSI) on the seismic response of pile-supported highway bridges. The collapse of 18 piers of the elevated Hanshin expressway during the 1995 Kobe earthquake (as well as of other bridges in California and around the would in recent earthquakes) has raised concerns about the current understanding of the seismic behavior of such structures and the adequacy of existing seismic regulations. In the case of Hanshin Expressway, preliminary examination of seismological and engineering information indicates that the dynamic interplay between soil, piles and superstructure may have contributed to the collapse of the bridge. A collaborative research program is being conducted involving a U.S. and a Japanese engineer to investigate the role of SSI on the collapse. The main objectives are: (i) to analyze the seismic response of the collapsed segment; (ii) to repeat the analysis for adjacent segments that did not collapse; (iii) to evaluate the results by comparing with results from earlier studies that did not consider SSI effects, and with predictions based on current seismic provisions. The Japanese collaborator is Dr. Takashi Tazoh, General Manager of the Geotechnical Division at Shimizu Corporation. He is providing seismological, geotechnical, and structural data for the site an is performing alternative analysis using analytical techniques pioneered at Shimizu. The research will be purely analytical; no experiments are planned. Apart from shedding light on the causes of the collapse, the research will develop practical analysis tools which can be of immediate value to engineers. This project is supported under the 3rd - Year Competition under NSF 98-36 "US - Japan Cooperative Research in Urban Earthquake Disaster Mitigation".