Earthquake response analysis of the Higashi-Kobe bridge

ABSTRACT

This paper presents results of observation and analysis fo the response of onte of the longest cable-stayed bridges in the world to the Hygoken-nambu (Kobe) eathquake of January 17, 1995. It is determined that intercation of the foundations of the bridge towers with the supporting soil plays a decisive role in the overall structural behavior. The key factor governing the changes of the soil properties at this site is pore water pressure builup, which results in liquefaction of the saturated surface soil layers unde large dynamic loads. Models of the soil and structure are created and initially validated by accurately simulating the system response to a small eathquake. Soil parameters reflecting the pore-water pressure builup in the strong eathquake are determied by advanced nonlinear effective stress analysis, combining the Ramberg-Osgood model of stress-strain dependence with a pore pressure model based on shear work concept. They are utilized to investigate and simulate the interaction of the foundation and the supporting 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. (AU)