Modeling Techniques for Strain-Range-Dependent Hardening Behavior of Low-Yield-Point Steel Shear Panel Dampers

Abstract

Shear panel dampers made of the low-yield-point steel exhibit significant overstrength under cyclic loading—a phenomenon that has been observed to depend not only on accumulated plastic deformations but also the loading amplitudes. This type of material behavior cannot be captured by using nominal metal plasticity models, and thus an extension—dubbed in this paper as the stepwise hardening model—is proposed. This model incorporates a set of kinematic and isotropic hardening variables that can be selectively activated or deactivated based on the strain amplitude. It can be incorporated into standard plasticity models using the so-called finite-element birth-death technique, which is available in most commercial finite-element analysis packages. In this paper, the authors implement the proposed extension onto the standard J2 plasticity model in general finite-element software using its parameter design language. The utility of the model is demonstrated by calibrating its parameters using force-displacement data from laboratory tests, and by carrying out numerical simulations to examine the evolution of damper shear force and energy consumption under different loading histories. The numerical studies performed in this paper indicate that the modified model can capture the hysteretic characteristics of low-yield-point steel dampers very well, which include their nonlinear transient and load–amplitude-dependent responses, as well as Bauschinger effects.