Probabilistic methods to evaluate the seismic vulnerability of reinforced concrete (RC) frames are largely used in the context of performance based design and assessment, often describing the structural response using global engineering demand parameters (EDPs) such as the interstory drift. While such EDPs are able to synthetically describe the structural behavior, the use of component level parameters of RC frames without seismic detailing can enable a more realistic and thorough description of failure mechanisms for structural vulnerability and loss assessment. This paper proposes a methodology for the probabilistic evaluation of seismic demand of low ductility RC frames by exploring a range of component level and global EDPs, identifying appropriate regression models and comparing performances of different ground motion intensity measures used in the probabilistic analysis. A realistic benchmark RC frame is used as a case study to identify key considerations in probabilistic seismic demand modeling.