Title: Modeling Hysteretic Force-Deformation Relationships for Reinforced Concrete Elements
Author(s): Murat Saatcioglu
Publication: Symposium Paper
Appears on pages(s): 153-198
Keywords: deformation; dynamic structural analysis; elastic properties; earthquake-resistant structures; hysteresis; mathematical models; models; reinforced concrete; structural analysis; Structural Research
Characteristic features of reinforced concrete response relevant to hysteretic modeling are discussed. The relationships between hysteretic features, and design and detailing parameters are illustrated. Experimentally obtained hysteretic force-deformation relationships are used to demonstrate the significance of each hysteretic feature on modeling. A brief review of selected hysteretic models is presented, Strength, as defined by primary curve, stiffness degradation, strength decay, and pinching of hysteresis loops are discussed as basic features of hysteretic response. The mechanisms behind these features and related design and detailing parameters are presented. The significance of each of these parameters in terms of deformation components resulting from flexure, shear, and reinforcement extension/slip is discussed. The dominant response shows stable hysteretic loops with little or no strength decay within the realistic range of deformations. Therefore, a simple hysteretic model may be appropriate for modeling flexural response. Shear response as well as hysteresis loops resulting from reinforcement slippage show pinching action, and hence should be modeled accordingly. Axial compression, lack of shear/confinement reinforcement, and poor anchorage of members may lead to early and rapid strength decay. Strength decay may have to be considered in such members. Stiffness degradation during unloading and reloading is a characteristic feature of reinforced concrete response, and should be considered in modeling all deformation components.