Investigation of The Effect of Earthquake Characteristics, Soil Properties And Damping on The Input Energy of Structures

This study investigates the combined influence of forward directivity (FD), site class, and damping ratio on the seismic input energy demand of linear single-degree-of-freedom (SDOF) systems using an energy-balance framework. Four near-fault ground-motion sets with FD and non-forward directivity (NFD) were compiled for ZC and ZD soil classes, and elastic input energy spectra were computed for damping ratios of 2%, 5%, and 20%. Analysis of the earthquake records showed that increasing the damping ratio from 2% to 20% reduced the peak average input energy by approximately 35-40% for the selected records. The effect of forward directivity in the selected ground motion is that the average input energy increases by approximately 35-50% in the ZC soil class, while this increase is almost three times greater in the ZD soil class. Overall, increasing damping systematically reduces peak mean input energy, while FD effects markedly amplify energy demand, especially on soft soils. These findings underline that near-fault pulse-like characteristics and site conditions should be jointly considered when interpreting energy-based seismic demand.