engleski

Retrofitting of short-to-medium-span concrete Bridges after strong intensity earthquakes

Bridges which were built before 1970s, either in the US or Japan or Europe, had been designed with little or no consideration for seismic demand. Majority of these bridges are supported by reinforced concrete bents and pier walls that lack the ductility and strength to resist earthquakes. Meanwhile strong motion earthquakes have revealed all vulnerable places on each of those bridges if built in seismically active region. After the 1971 San Fernando earthquake the US started several seismic retrofit programs. Retrofit programs in the 1980s included the first use of isolators on bridges and a program to retrofit single-column bents. These programs were greatly accelerated after the 1989 Santa Cruz (Loma Prieta) and 1994 Northridge earthquakes. After the 1994 Northridge earthquake it was observed that no serious damage would have occurred if the previous retrofit program had already been implemented. Japan also started similar programs, especially after the 1995 Kobe earthquake. Europe may not be out of this global problem and must have own retrofit program not only for buildings (Eurocode 8, Part 3: Assessment and retrofitting of buildings, EN 1998-3:2005) but for bridges as well. Some solutions for retrofitting the abutment, bent and column of concrete bridges recommended in these programs as well as some recommendations and comments made by the author is presented in this paper.

Earthquake loading; Retrofit program; Concrete Bridge; Ductility; Strength; Bent

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