Updates to Maps for the 2015 NEHRP Recommended Seismic Provisions

Why:The National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions for New Buildings, a forerunner of earthquake codes for buildings in this country, was published in a new edition in 2015. The new edition will include updated maps showing the Maximum Considered Earthquake (MCE) across the United States.

What: This presentation explains the current updates to the maps and compares the new values with those contained in the current and previous edition of the American Society of Civil Engineer's Standard ASCE 7, Minimum Design Loads for Buildings and Other Structures. Standard ASCE 7 provides requirements for general structural design and includes means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, and their combinations that are suitable for inclusion in building codes and other documents. ASCE 7 is an integral part of the building codes of the United States. This presentation also demonstrates the US Geological Survey's new design map tool.

How With the 2014 update of the U.S. Geological Survey National Seismic Hazard Model (NSHM) as a basis, the Building Seismic Safety Council (BSSC) updated the earthquake ground motion maps in the National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions for New Buildings and Other Structures. Most of the updated values are within a ±20% change of the existing values. Most of the larger changes are due to the USGS NSHM updates.