SEISMIC RESPONSE OF BRIDGE STRUCTURES WITH POTENTIAL LIQUEFACTION SUBSURFACE CONDITION CASE STUDY: SEISMIC RETROFIT OF THE MISSION VALLEY VIADUCT IN SANDIEGO, CALIFORNIA

The potential for subsurface liquefaction has been known for some time, but the effect of this phenomena during a major seismic event on the bridge foundation is relatively unknown. The Mission Valley Viaduct (approximately ۴۰۰۰ feet) and the interchange is founded on soil which has been known to have severe liquefaction problem. The California Department of Transportation (CALTRANS) undertook this seismic retrofit project and developed seisnuc design procedures, plans, special provisions, and a construction co::t of $۴۰,۰۰۰,۰۰۰. The bulk of this cost is in the foundation retrofit. The construction of this project is scheduled to start Nov-۱-۱۹۹۴. This project is the first retrofit contract by CALTRANS where the components of the foundation system are proportioned to limit the movement of such loundation in liquefied soil.This paper will provide the most recent practice in scismic retrofit of bridge structures in liquefiable soil.