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.
