RESPONSE ANALYSIS OF THE HIGASHI-KOBE BRIDGE AND SURROUNDING SOIL IN THE 1995 HYOGOKEN-NANBU EARTHQUAKE

This paper presents results of observation and analysis of the respons e of one of the longest cable-stayed bridges in the world to the Hyogo ken-Nanbu (Kobe) Earthquake of 17 January 1995. It is determined that interaction of the foundations of the bridge towers with the supportin g soil plays a decisive role in the overall structural behaviour. The key factor governing the changes of the soil properties at this site i s pore-water pressure buildup, which results in liquefaction of the sa turated surface soil layers under large dynamic loads. Models of the s oil and structure are created and initially validated by accurately si mulating the system response to a small earthquake. Soil parameters re flecting the pore-water pressure buildup in the strong earthquake are determined by an advanced non-linear effective stress analysis, combin ing the Ramberg-Osgood model of stress-strain dependence with a pore p ressure model based on shear work concept. They are utilized to invest igate and simulate the interaction of the foundation and the supportin g soil using the program SASSI with the flexible volume substructuring approach. The results show a good agreement with the observations and have useful implications to the scientific and engineering practice. (C) 1998 John Wiley & Sons, Ltd.