Preparation of Seismic Design Maps for Codes

resented by:

Nicolas Luco, Research Structural Engineer
USGS, Golden, Colorado

About this Seminar Series
Next Generation Attenuation (NGA) Models
This seminar informs structural and geotechnical engineers about the implications for engineering practice of the recently developed next generation attenuation (NGA) models. Significant changes are coming to the USGS Hazard Maps and Seismic Design Maps that are part of the ASCE 7 and IBC design process. These changes need to be understood by geotechnical, seismological, and structural engineers; not only will they impact site-specific studies, but they will also become a part of the 2010 ASCE 7 and 2012 IBC design provisions. This seminar provides the background and basis for the NGA models and how they impact the new USGS Hazard Maps. It also summarizes the technical basis of the three major changes to Seismic Design Maps. It provides examples of applications of the new NGA models.

The NGA models that are now incorporated in the new USGS Hazard Maps were developed by the Pacific Earthquake Engineering Research (PEER) Center over a five-year period to update the ground motion predictive equations for shallow crustal earthquakes in the western United States and similar active tectonic regions. The expansion of the strong motion database for large earthquakes at near-field distances provided an opportunity to significantly improve previous ground motion models. The use of these models has resulted in significant decreases in the hazards maps in the longer period (1.0 secs and above) spectral values.

Funding for the technical seminar is provided under a cooperative agreement (EMW-2008-CA-0625) with FEMA/US Department of Homeland Security.