BASE ISOLATION - AN INNOVATIVE REHABILITATION TECHNIQUE FOR EARTHQUAKES

The issue of bridge rehabilitation has received increasing political and engineering attention over the past five years and funding levels are beginning to approach levels where significant planning and construction progress can now be made. Major aspects of the rehabilitation problem include the replacement or upgrading of deteriorated decks, an upgrade or realistic assessment of the load rating and the replacement of non-functioning or badly corroded bearings. An increasing trend exists towards the replacement of steel rocker and roller type bearings with elastomeric bearings. The incorporation of a lead plug and a slight increase in the height of elastomeric bearing can increase the level of earthquake resistance of a bridge by factors of 5 to 10. The paper focuses on this aspect of bridge rehabilitation.