Effects of Column Flexural Strength on the Seismic Response of a Multiple-Column Bridge Bent

The effect of varying column flexural strengths on the seismic performance of a pre-1970, reinforced concrete multiple-column bridge bent was investigated. The strength variations may arise from poor detailing, retrofitting of existing structures, over- or under-design, or construction errors. The seismic behavior of the system was determined using inelastic response history analysis. The effects of possible strength variations were evaluated with respect to a base level of expected performance, with respect to various foundation flexibilities, and with respect to ground shaking intensity. The analyses show that the distribution of inelastic demands within the system is sensitive to foundation restraint and relatively insensitive to small flexural strength changes. The analyses also show that changes in the column strength in one location may increase the damage potential at other locations within the structure.