Performance Evaluation and Surrogate Optimization of an NCW–VFD Stiffness–Damping Zoned Seismic Mitigation System for Laboratory Buildings With Open Lower Stories

ABSTRACT Laboratory buildings with open lower stories require simultaneous control of lower‐story drift and floor acceleration in equipment‐sensitive upper stories, whereas a single stiffness‐ or damping‐based control mechanism is often insufficient. This study proposes a stiffness–damping zoned seismic mitigation system. It combines lower‐story nonbuckling corrugated steel shear walls (NCWs) and upper‐story viscous fluid dampers (VFDs). The NCWs provide lateral stiffness and share lower‐story shear. The VFDs dissipate seismic input energy and reduce peak floor acceleration. A laboratory building in a high seismic region is used as the prototype. Three schemes are compared: VFD‐only, BRB‐only, and NCW + VFD. Component‐level tests were conducted to verify the mechanical properties of the NCWs and VFDs adopted in the numerical model. Nonlinear time‐history analysis, incremental dynamic analysis, fragility analysis, and Kriging‐based multiobjective optimization are performed. The results show that NCW + VFD keeps the drift demand close to BRB only and the acceleration demand close to VFD only. The acceleration safety factor reaches 2.00. The optimized scheme reduces peak floor acceleration by 3.45% and device demand by 13.43%. The proposed system provides a practical solution for function‐sensitive buildings with large‐span lower stories.