Estimating structural collapse fragility of generic building typologies using expert judgment

The structured expert elicitation process proposed by Cooke (1991),
hereafter referred to as Cooke’s approach, is applied for the first time
in the realm of structural collapse-fragility assessment for selected generic
construction types. Cooke’s approach works on the principle of objective
calibration scoring of judgments coupled with hypothesis testing used in classical
statistics. The performance-based scoring system reflects the combined
measure of an expert’s informativeness about variables in the problem area
under consideration, and their ability to enumerate, in a statistically accurate
way through expressing their true beliefs, the quantitative uncertainties
associated with their assessments. We summarize the findings of an expert
elicitation workshop in which a dozen earthquake-engineering professionals
from around the world were engaged to estimate seismic collapse fragility for
generic construction types. Development of seismic collapse fragility
functions was accomplished by combining their judgments using weights
derived from Cooke’s method. Although substantial effort was needed to
elicit the inputs of these experts successfully, we anticipate that the elicitation
strategy described here will gain momentum in a wide variety of earthquake
seismology and engineering hazard and risk analyses where physical model
and data limitations are inherent and objective professional judgment can fill
gaps.