ABSTRACT

Five models of a typical bridge pier at 0.45 scale were constructed in their original (1950’s) as-built condition. Four were then retrofitted following several alternative schemes. In the structural laboratory at the University of British Columbia, each bent was subjected to sequences of lateral slow cyclic loading, which was increased for each sequence up to a high damage level. Between the sequences, corresponding to increasing levels of structural damage, forced vibration tests were performed on the bents with an instrumented hammer. Frequency domain analyses of the experimental data were performed to identify dynamic characteristics of each bent at each level of structural damage. The decreasing fundamental frequencies were related to the increasing ductility demands, the latter reflecting the structural damage of the bents. Sensitivity analyses were also performed to relate damping ratio changes to ductility levels imposed on the specimens.