Abstract: Piers are key components in a lateral force resisting system of bridge structures. To implement the multiple performance objectives of probability-based and performance-based seismic design for bridge structures, the probabilistic capacity of piers need to be calculated at various performance limit states. Based on previous research works, 5 seismic performance levels and 4 corresponding performance limit states are defined for RC bridge columns. The deterministic formula for deformation capacities of RC bridge columns at each performance limit state is derived from equivalent plastic hinge theory. On the basis of quasi-static test results of 183 rectangular flexure dominant RC bridge columns, the coefficients associated with the axial-load ratio, aspect ratio and stirrup characteristic value in the formula are determined by a multiple regression analysis. Considering the epistemic uncertainty of the deterministic formula, a probabilistic deformation capacity model for rectangular RC bridge columns is developed based on both the deterministic formula and the quasi-static test results. A case study for a typical RC bridge column shows that the probabilistic model can be applied to the probability-based and performance-based seismic design and the evaluation of bridge structures.