The capacity and expected seismic damage of several types of steel buildings are assessed by using a probabilistic approach. Nonlinear static and dynamic analyses are performed by means of Monte Carlo Simulations. Concerning to the nonlinear static approach, it is shown that a new damage model, recently developed for reinforced concrete buildings, also holds for steel buildings. The new damage index is defined as a combination of the energy dissipation and the one of the secant stiffness degradation; both functions are obtained from the capacity curve in a straightforward way. The analyzed buildings are archetypal of the Mexico City and the seismic actions are selected so that they are compatible with the design spectra provided in the seismic code. The results show that, in average, the Park and Ang index, calculated by means of incremental dynamic analysis, is well fitted by the combination of the contributions to damage of the stiffness degradation (71%) and the one of the energy loss (29%). The obtained results confirm that the new damage model can be a powerful tool for probabilistic assessments of seismic damage.