Experimental cyclic behavior and constitutive modeling of low yield point steels

To fundamentally define the cyclic behavior of low yield point steel (LYP) and obtain representative material constitutive parameters for structural analysis, experimental studies of LYP100 and LYP160 steels were conducted under a range of loading scenarios. Monotonic and cyclic loading patterns were used to evaluate overall response characteristics and to quantify strength, ductility and energy dissipation capacity. Based on this experimental data, the essential material parameters of two constitutive models were calibrated. These constitutive models were then employed in structural analysis of previous large-scale steel plate shear wall test specimens, and the analysis results agreed well with the test data. Together, the experiments and analyses conducted in this study indicate that, although the yield strengths of LYP steels are by design less than conventional and high strength steels, characteristics that are important for seismic behavior - such as cyclic response, ductility and energy dissipation capacity - are improved. Cyclic response of LYP steel is characterized by combined isotropic and kinematic hardening, and the isotropic component plays a more significant role. LYP steel is a promising structural material that can be employed more effectively when its cyclic behavior, including appreciable hardening, is defined through experimental studies and constitutive modeling as presented here.