Novel Geomechanics Concepts for Earthquake Excitations Applied in Time Domain

Novel geomechanics concepts for seismic design satisfying the current performance-based seismic design (PBSD) requirements are presented. Issues related to soil conditions are explicitly addressed. To satisfy the underlying dynamics as realistically as possible, structures are represented by finite elements and the earthquake excitations are applied in time domain. PBSD is essentially a sophisticated risk-based design concept. To incorporate uncertainty in the seismic loading, the current design guidelines require the consideration of at least 11 design earthquake time histories. For wider acceptance, information on the seismic risk is extracted using multiple deterministic analyses. The proposed concept is showcased by estimating the underlying risk of a nine-story steel building designed by experts for several performance levels and different soil conditions. The basic intent of PBSD is to limit the probability of collapse to about 0.10. The study confirms that the building was well designed by the experts and the proposed method confirms this requirement. The authors believe that they proposed an alternative to simulation and the classical random vibration concept.