Some retrofitting techniques for Albanian bridge

Abstract

Based in the world experience about on the seismic design of new bridges and retrofitting of existing ones, now days in Albania it is one of the priority to the implementation of modern codes (Euro codes). Generally the bridges were designed for nominal seismic forces without provisions of ductility. So it is understandable that the earlier designed bridges will not be able to resist the effects of earthquakes in the future. These structures may require seismic evaluation and retrofitting. The protection of bridges from damage in earthquakes has direct relevance in prevention of aggravation of disaster, as disruption of transportation routes hampers relief and rescue operations immediately following the earthquake. Several retrofitting techniques have been developed for bridges in recent years. Many of the existing bridges can be retrofitted by these techniques. This paper presents the important issues: structural deficiencies; retrofit philosophy, retrofit techniques, recent developments and effectiveness of retrofit techniques. In Albania the most prevalent type of the old bridges are simple supported span and the new bridges are simple supported superstructures with continued slab. The most commonly observed type of failure for this type of bridges is a girder falling off the supports due to longitudinal response. To prevent such type of failure, the adjoining spans should be interconnected by connection rods/restrainers/linkage bolts.