Idealized backbone model for existing reinforced concrete columns and comparisons with FEMA 356 criteria

An idealized backbone model defining the key damage states of an existing reinforced concrete column (flexural yielding, shear failure, and axial load failure) is developed using drift capacity models. Assumptions and limitations of the drift capacity models are discussed. To demonstrate the application of the idealized backbone model to the evaluation of existing reinforced concrete columns, the model is compared to data from shake table tests and measured drifts from an instrumented building damaged during the Northridge earthquake. The results from the backbone model are also compared with modeling parameters recommended in current seismic rehabilitation guidelines.