engleski

Seismic retrofitting of concrete bridges

Bridges which were built before 1970s, either in U. S. or Japan or Europe, had been designed with little or no consideration for seismic demand. Majority of these bridges are supported on reinforced concrete bents and pier walls that lack the ductility and strength to resist earthquakes. Meanwhile strong motion earthquakes revealed all vulnerable places on each of those bridges if built in seismically active region. After the 1971 San Fernando earthquake U. S. 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. 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 authors will be presented in this paper.

earthquake loading; ductility; retrofit programs; strengthening

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