Existing ground motion selection methods for the seismic assessment of structural systems consider only spectral compatibility as selection objective. Other important earthquake parameters such as those related to regional seismicity, local soil conditions, strong ground motion intensity and duration are considered indirectly by setting them as selection constraints. This study presents a new framework for the optimum selection of earthquake ground motions, where more than one objectives are considered explicitly in the selection procedure including objectives that are not directly related to spectral matching. To address the multi-objective nature of the optimization problem examined herein, the weighted sum method is used that supports decision making both in the pre-processing and post-processing phase of the selection procedure. The optimum selections are conducted by the use of a mixed-integer genetic algorithm that is able to track near-global optimal solutions of constrained problems with both discrete and continuous design variables. It is found that proposed methodology is able to select ground motion sets that are both spectrum compatible and representative of the seismic conditions of the structural system under investigation
