Earthquakes represent one of the most destructive natural disasters and the devastating consequences of numerous seismic incidents that occurred across the world have emphasized the significance of seismic performance assessment of structures. Fragility function is defined by the conditional probability of a particular structure exceeding a certain damage state when subjected to seismic excitations. Eventually, for the development of fragility functions, characterization of structural behavior and quantification of structural damage during seismic events are pertinent. The basic requirement in modeling reinforced concrete (RC) structural components under seismic loading is to define a constitutive load-deformation relationship capable of producing strength and stiffness degradation along with pinching at all displacement levels. This is a demanding task considering the numerous parameters contributing to the structural hysteretic behavior. This book delineates the structural hysteretic behavior and different damage states experienced by RC buildings for the derivation of seismic fragility functions.