Multiobjective Optimization Design of a MDOF Structure with Attached Nonlinear Gas–Spring Damper

To maximize vibration reduction efficiency and reduce the risk of detuning, this study proposes a multiobjective optimization design method for shape parameters affecting the nonlinear characteristics of nonlinear gas-spring damper (NGSD) based on the NSGA-II algorithm. A numerical model of a MDOF structure with attached NGSD is developed and optimized under white noise excitation, and the effectiveness of the optimized NGSD in mitigating structural seismic responses is validated through shaking table tests. By comparing with the optimal TMD, the control effectiveness and parameter sensitivity of the optimized NGSD under various near- and far-field seismic excitations are investigated. Results show that the optimization design is carried out with the performance objective of minimizing the RMS of structural displacement and acceleration response, and a set of relatively optimal piston radius and initial volume parameters are obtained, resulting in the control effectiveness of NGSD on the RMS response of MDOF structure’s displacement and acceleration as high as 77% and 39%, respectively. The maximum reduction effectiveness of optimized NGSD on the peak structural acceleration and displacement response under seismic excitation is 18% and 19% respectively, and the RMS reduction ratios are even as high as 56% and 61%, indicating the efficacy of using NSGA-II for parameter optimization. Moreover, the optimized NGSD demonstrates comparable control effectiveness to the optimal TMD with a shorter stroke and stable performance across different seismic excitations, indicating low sensitivity of optimal parameters to excitation frequency.