Parameter optimization for pivot hysteresis model for reinforced concrete walls with different failure modes

Abstract

AbstractReinforced concrete structural walls are major vertical lateral load‐resisting members in reinforced concrete structures located in seismic regions. It is important to understand and evaluate the hysteresis behavior of these members for an efficient earthquake‐resistant design. Among the various models available for estimating this hysteretic behavior, the Pivot hysteresis model, which models hysteretic behavior through parameters α and β, respectively, representing the unloading stiffness and pinching behavior, has been effective and efficient for use with columns. In this paper, an effort is made to extend the application of the Pivot hysteresis model to reinforced concrete walls. Key variabratiosuch as axial load ratio, wall height‐to‐length ratio, web reinforcement indices, boundary element reinforcement indices, and length‐to‐effective thickness ratio were considered to derive expressions for α and β suitable for walls. Equations for α and β were calibrated through the hysteretic test data of 108 wall specimens subjected to cyclic loading and exhibiting different failure modes. The calibration is based on the optimization of energy dissipation for specimens from the collated database—a numerically complex task achieved through a superior optimization technique known as Simulated Annealing. The proposed formulations showed reasonably good accuracy in predicting complex hysteretic responses when verified against an extensive database of wall test specimens with flexural and shear modes of failure.