Seismic Evaluation of a 30-Year Old Non-Ductile Highway Bridge Pier and ItsRetrofit

摘要

An experimental investigation of the seismic behavior of a full-scale prototypecap beam-to-column subassemblage and its retrofit are reported. The joint core failure of the pre-retrofitted specimen under reverse cyclic loading was attributed to anchorage loss of column steel and fatigue failure of the concrete. The retrofit aimed at providing an elastic joint and cap beam as well as enhanced column rebar anchorage. Lateral loads were applied to the retrofitted specimen with increasing drift amplitudes up to 5.4% such that displacement amplitudes were the same as the pre-retrofitted specimen whose maximum drifted amplitude was 5.0%. Ductility capacities predicted by existing code-based methods fall short of that observed during the experiments for either specimen. The ATC 6-2 Capacity/Demand seismic evaluation method shows the pier to be unsafe in Seismic Performance Categories C and D. However, in spite of poor detailing, significant ductility capacities were demonstrated in the experiments which suggest satisfactory performance for much larger Peak Ground Accelerations than those predicted by the ATC 6-2.