The evaluation of the damage caused by horizontal loads, such as seismic action, to existing bridges has received an important attention in recent years, because it is the first step towards reducing casualties and economic losses. In damage detection and evaluation, the application of simple and reliable models has been prioritized, because they are necessary in further multi-analyses required by Monte Carlo simulations. A simplified moment–curvature damage evaluation model, capable of evaluating the expected seismic behavior of RC highway bridges is proposed in this paper. The damage of a pier is related to the reduction of the cross-sectional moment of inertia of the bridge piers. Therefore, the evaluation of the damage is based on a non-linear analysis determining the changes of the mentioned moment of inertia. The model was validated using experimental results obtained at the JRC Ispra for the Warth Bridge of Austria and also FEM analyses performed by other authors for the same bridge.