Engineered Yield-Surface Shaping in Sands for Optimized Seismic Performance: Enhancing Energy Dissipation, Settlement Control, and Self-Centering Capacity

Abstract The seismic performance of soil–foundation–structure systems is inherently governed by the constitutive behavior of the underlying soil, which is commonly represented through its yield surface in stress space. Conventional soil behavior models adopt yield surfaces derived from empirical or phenomenological observations, without intentional engineering of their geometry or evolution. This study introduces a novel paradigm—engineered yield-surface shaping—in which the form, orientation, and hardening/softening characteristics of the soil’s yield surface are deliberately modified to optimize dynamic performance under earthquake loading. The core hypothesis is that, by tailoring the geometry of the yield surface in sands, it is possible to simultaneously increase hysteretic energy dissipation, reduce residual settlements, enhance self-centering capacity, and improve resistance to liquefaction. The proposed approach explores both micro-scale and macro-scale engineering strategies, including controlled layering with variable stiffness, insertion of inclusions or micro-reinforcement, local modification of gradation or cementation, and targeted soil improvement to introduce anisotropy or multi-surface yielding zones. Analytical development focuses on a generalized plasticity framework capable of representing customized yield-surface shapes in p–q–θ space, enabling quantitative mapping between yield-surface parameters and key seismic performance indices. Advanced constitutive models (e.g., PM4Sand, bounding-surface plasticity, and multi-yield-surface formulations) are adapted to incorporate engineered shapes and are calibrated against cyclic triaxial and simple shear test data on both natural and engineered specimens. Numerical simulations are performed using OpenSeesPy, covering a wide range of seismic loading conditions and soil–foundation configurations. Multi-objective optimization techniques are employed to identify yield-surface geometries that maximize energy dissipation while minimizing residual deformation and structural demand. The optimized configurations are further validated through small-scale shake table and centrifuge tests, allowing direct comparison of engineered and conventional soils under identical seismic inputs. Performance metrics include effective damping ratio, stiffness degradation rate, residual settlement ratio, re-centering index, and cycles-to-liquefaction threshold. Results demonstrate that yield-surface shaping can lead to performance gains of 20–50% in damping capacity, 30–70% reduction in residual settlement, and significant improvement in post-shaking recovery compared to conventional soils. This work establishes engineered yield-surface shaping as a transformative tool in seismic geotechnical engineering, bridging constitutive modeling, material tailoring, and performance-based earthquake design. Keywords Engineered Yield Surface Seismic Soil Behavior Energy Dissipation Residual Settlement Self-Centering Capacity Soil Constitutive Modeling Plasticity Theory Soil Improvement Liquefaction Resistance Cyclic Loading