Semi-Automated Procedure to Estimate Nonlinear Kinematic Hardening Model to Simulate the Nonlinear Dynamic Properties of Soil and Rock

The strain-dependent nonlinear properties of ground materials, such as shear modulus degradation (G/G(max)) and damping, are of significant importance in seismic-related analyses. However, the ABAQUS program lacks a comprehensive procedure to estimate parameters for a built-in model. In this study, a nonlinear kinematic hardening (NKH) model with three back-stress values was used, which allows better fitting to the backbone curves compared to the simplified nonlinear kinematic hardening (SNKH) model previously proposed. Instead of modeling in ABAQUS, a semi-automated procedure was implemented in MATLAB, which can predict shear stress-shear strain hysteretic loops, to find the fitting parameters to the target G/G(max) and/or damping curves. The procedure was applied for three soil and two rock samples, and the results indicate a good match between model and target backbone curves, which proves the application of the procedure and the NKH model in simulating the nonlinear properties of ground materials.

Automated summary

This study utilized a nonlinear kinematic hardening (NKH) model and implemented a semi-automated procedure in MATLAB for fitting backbone curves, resulting in good matches with target curves. The results demonstrate the effectiveness of the procedure and NKH model in simulating the nonlinear properties of ground materials.