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Wood construction comprises a large portion of building stocks of several countries across the globe with high preparedness for earthquakes including Japan, Canada, and the United States. Built environments of these countries are prone to long-duration ground shakings due largely to the proximity of subduction faulting systems. However, the current seismic design requirements do not adequately emphasize this key feature of ground motions. This study evaluates the impact of long-duration ground motions on seismic risk characteristics of code-conforming wood lightframe buildings. To this end, a study matrix of wood light-frame buildings is developed incorporating with two different heights (i.e., 1-story and 4-story) and two distinct occupancies (i.e., multi-family and commercial) designed for a very high seismic region according to the latest pertinent design requirements of the United States. The seismic performance of these buildings is assessed through incremental dynamic analysis (IDA) in accordance with FEMA P-695 recommendations. Each building is analyzed using three sets of ground motions, i.e., far-field FEMA P-695 ground motions ensemble, an ensemble of short-duration ground motions, and an ensemble of long-duration ground motions. For each building, structural responses are obtained, and collapse fragility for these three sets of ground motions are derived. Next, the structural analysis results are relayed to a component-based loss assessment framework developed based on performance-based earthquake engineering principles in order to predict the seismic risk characteristics of the adopted buildings including the vulnerability function, risk curve, and average annual loss (AAL). The loss assessment is conducted separately for the structural and nonstructural components as well as the content of the buildings. The study reveals the considerable effect of ground motion duration on the seismic vulnerability of light-frame wood buildings, specifically in the case of 4-story wood light-frame building which reveals approximately a mean increase of 140.0% in the predicted losses.


This paper was presented at the 17th World Conference on Earthquake Engineering, 17WCEE

Sendai, Japan - September 13th to 18th 2020