Department of Civil & Environmental Engineering Earth Science
January 23, 2013
258 Fitzpatrick Hall, 1:00 p.m.-2:00 p.m.
George P. Mavroeidis, Ph.D.
Assistant Professor
Department of Civil Engineering
Catholic University of America
Title:
Strong Ground Motions in the Near-Fault Region: From Earthquake Source Description, to Ground Motion Modeling, and to Dynamic Structural Response
Abstract:
Sites located in the immediate vicinity of active tectonic faults have large potential to experience ground motions characterized by intense pulses of relatively long duration in the event of an earthquake. Forward rupture directivity and permanent translation (fling) are the two most common effects that give rise to such strong motion pulses. Long-period structures (e.g., base-isolated buildings, long-span bridges, tall buildings) are particularly susceptible to seismic excitations of this kind. Despite the significant progress that has been made by seismologists and engineers over the last 10-15 years, there are still several issues that need to be addressed pertaining to the physical understanding, characterization, proper parameterization, analytical modeling and numerical simulation of near-fault translational and rotational ground motions, as well as to their effects on the seismic response of engineering structures. The primary topics to be discussed in this presentation include (1) description of the primary characteristics of the near-fault strong ground motions; (2) derivation of an analytical model for the representation of the coherent component of the near-fault seismic excitations; (3) derivation of a simplified methodology for generating realistic broadband ground motion time histories in the near-fault region; (4) investigation of the effects of soil conditions and tectonic region on the pulse period of near-fault ground motions; (5) investigation of the elastic and inelastic response of the single-degree-of-freedom (SDOF) system subjected to near-fault ground motions, including the specification of design spectra, reduction factors and damping modification factors for analysis and design in the near-fault region; (6) investigation of the effects of fault rupture characteristics on near-fault ground motions; (7) description of the primary characteristics of near-fault dynamic ground deformations (i.e., strain, rocking, and torsion); and (8) investigation of the effects of rotational ground motions on the dynamic response of engineering structures. The results are based on an interdisciplinary approach that ranges from the description of the earthquake source, to ground motion modeling, and to dynamic structural response.