Controller-dependent robustness limits in actuator-constrain

•Frozen MPC and ASMC are compared under identical actuator constraints. •MPC is mainly drift-limited, while ASMC is base-displacement-limit.

This study investigates that problem using a benchmark-scale four-degree-of-freedom adaptive-foundation model subjected to coupled earthquake-flood loading. Constrained model predictive control (MPC) and an LQR-informed adaptive sliding-mode controller (ASMC) are frozen after selection and compared through the same first-order lateral actuator, 5-ms sampling interval, and symmetric 4-kN command limit.