Abstract | The effect of different element modeling formulations for reinforced concrete (RC) elements on the predicted performance of an RC building under seismic excitation is examined. The building selected is a typical existing five-story RC frame designed for moderate seismicity in the late 1960s, according to the older generation of Greek seismic codes with no special provisions for ductile behavior. Fiber elements are used to model the beams and columns using both stiffness and flexibility formulations, which lead to distinctly different behaviors. To evaluate the seismic performance of each alternate model, both static pushover and incremental dynamic analysis are used. The results are compared across all models, both at the local and the global level, to reveal the differences in the predicted seismic performance resulting from such a subtle modeling choice.