You Designed It for the Big One, Right?: Illustrating and Communicating Uncertainty in a Deterministic Seismic Hazard Analysis

by B. Tom Boardman, P.E., Associate Civil Engineer; East Bay Municipal Utility District, Oakland, CA, tom.boardman@ebmud.com,
, G.E.

Serial Information: Geo-Strata —Geo Institute of ASCE, 2016, Vol. 20, Issue 6, Pg. 54-60


Document Type: Feature article

Abstract: In seismic regions of the U.S. and worldwide, engineers design structures to withstand seismic ground motions resulting from a large, rare earthquake. But definitions of "large" and "rare" depend on who you talk to, your perceptions of uncertainty, and how these terms are defined by the public agency responsible for assuring that projects are designed to an acceptable safety level. Difficulty arises when trying to explain to your professional colleagues the large uncertainty inherent in the seismic design values, and even more importantly, to the public who will rely on your recommendations. Typically, "large" refers to the earthquake magnitude and the resulting ground motions, and "rare" refers to time between events, but often these terms are blurred and become one and the same to a non-technical audience. What most people want to know, and what you are often asked, is, "You designed it for the Big One, right?"

Subject Headings: Seismic design | Seismic tests | Ground motion | Uncertainty principles | Earthquakes | Structural reliability

 

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