Collapse Risk of Buildings in the Pacific Northwest Region due to Subduction Earthquakes

2015 ◽  
Vol 31 (4) ◽  
pp. 2087-2115 ◽  
Author(s):  
Meera Raghunandan ◽  
Abbie B. Liel ◽  
Nicolas Luco
Keyword(s):  
Pacific Northwest ◽  
Ground Motions ◽  
Cascadia Subduction Zone ◽  
Subduction Earthquakes ◽  
Crustal Earthquakes ◽  
The Pacific ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
Northwest Region ◽  
Modern Building

Subduction earthquakes similar to the 2011 Japan and 2010 Chile events will occur in the future in the Cascadia subduction zone in the Pacific Northwest. In this paper, nonlinear dynamic analyses are carried out on 24 buildings designed according to outdated and modern building codes for the cities of Seattle, Washington, and Portland, Oregon. The results indicate that the median collapse capacity of the ductile (post-1970) buildings is approximately 40% less when subjected to ground motions from subduction, as compared to crustal earthquakes. Buildings are more susceptible to earthquake-induced collapse when shaken by subduction records (as compared to crustal records of the same intensity) because the subduction motions tend to be longer in duration due to their larger magnitude and the greater source-to-site distance. As a result, subduction earthquakes are shown to contribute to the majority of the collapse risk of the buildings analyzed.

Collapse Risk of Buildings in the Pacific Northwest Region due to Subduction Earthquakes

2014 ◽  
pp. 141212055555007 ◽  
Author(s):  
Meera Raghunandan ◽  
Abbie B. Liel ◽  
Nicolas Luco
Keyword(s):  
Pacific Northwest ◽  
Subduction Earthquakes ◽  
The Pacific ◽  
Northwest Region

Effects of Deep Basins on Structural Collapse during Large Subduction Earthquakes

2017 ◽  
Vol 33 (3) ◽  
pp. 963-997 ◽  
Author(s):  
Nasser A. Marafi ◽  
Marc O. Eberhard ◽  
Jeffrey W. Berman ◽  
Erin A. Wirth ◽  
Arthur D. Frankel
Keyword(s):  
Pacific Northwest ◽  
Ground Motions ◽  
Sedimentary Basins ◽  
Spectral Shape ◽  
Hazard Maps ◽  
Structural Collapse ◽  
Subduction Earthquakes ◽  
Long Duration ◽  
The Pacific ◽  
Spectral Accelerations

Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is implicitly considered in seismic hazard maps used in U.S. building codes. The basin amplification of ground motions from subduction earthquakes is particularly important in the Pacific Northwest, where the hazard at long periods is dominated by such earthquakes. This paper evaluates the effects of basins on spectral accelerations, ground-motion duration, spectral shape, and structural collapse using subduction earthquake recordings from basins in Japan that have similar depths as the Puget Lowland basin. For three of the Japanese basins and the Puget Lowland basin, the spectral accelerations were amplified by a factor of 2 to 4 for periods above 2.0 s. The long-duration subduction earthquakes and the effects of basins on spectral shape combined, lower the spectral accelerations at collapse for a set of building archetypes relative to other ground motions. For the hypothetical case in which these motions represent the entire hazard, the archetypes would need to increase up to 3.3 times its strength to compensate for these effects.

Spectral damping scaling factors for horizontal components of ground motions from subduction earthquakes using NGA-Subduction data

2021 ◽  
pp. 875529302110279
Author(s):  
Sanaz Rezaeian ◽  
Linda Al Atik ◽  
Nicolas M Kuehn ◽  
Norman Abrahamson ◽  
Yousef Bozorgnia ◽  
...  
Keyword(s):  
Ground Motions ◽  
Damping Ratio ◽  
Spectral Shape ◽  
Parametric Models ◽  
Scaling Factors ◽  
Global Models ◽  
Motion Models ◽  
Subduction Earthquakes ◽  
Crustal Earthquakes ◽  
Subduction Zone Earthquakes

This article develops global models of damping scaling factors (DSFs) for subduction zone earthquakes that are functions of the damping ratio, spectral period, earthquake magnitude, and distance. The Next Generation Attenuation for subduction earthquakes (NGA-Sub) project has developed the largest uniformly processed database of recorded ground motions to date from seven subduction regions: Alaska, Cascadia, Central America and Mexico, South America, Japan, Taiwan, and New Zealand. NGA-Sub used this database to develop new ground motion models (GMMs) at a reference 5% damping ratio. We worked with the NGA-Sub project team to develop an extended database that includes pseudo-spectral accelerations (PSA) for 11 damping ratios between 0.5% and 30%. We use this database to develop parametric models of DSF for both interface and intraslab subduction earthquakes that can be used to adjust any subduction GMM from a reference 5% damping ratio to other damping ratios. The DSF is strongly influenced by the response spectral shape and the duration of motion; therefore, in addition to the damping ratio, the median DSF model uses spectral period, magnitude, and distance as surrogate predictor variables to capture the effects of the spectral shape and the duration of motion. We also develop parametric models for the standard deviation of DSF. The models presented in this article are for the RotD50 horizontal component of PSA and are compared with the models for shallow crustal earthquakes in active tectonic regions. Some noticeable differences arise from the considerably longer duration of interface records for very large magnitude events and the enriched high-frequency content of intraslab records, compared with shallow crustal earthquakes. Regional differences are discussed by comparing the proposed global models with the data from each subduction region along with recommendations on the applicability of the models.

scholarly journals (Re)considering Squirrel––From Object of Rescue to Multispecies Kin

2018 ◽  
Vol 43 (1) ◽  
pp. 60-67
Author(s):  
Angela Molloy Murphy
Keyword(s):  
Early Childhood ◽  
Pacific Northwest ◽  
Classroom Community ◽  
Early Childhood Classroom ◽  
Childhood Education ◽  
Nature And Culture ◽  
The Pacific ◽  
Child Centered ◽  
Northwest Region

This is a story situated in the Pacific Northwest region of North America, where encounters with a non-native “rescue” squirrel present disequilibrium for an educator and surprises for an early childhood classroom community. Thinking with Haraway, Latour, and common world frameworks challenges the educator’s “back to nature” narrative and generates opportunities to engage with different perspectives about the intersection of nature and culture, human and nonhuman kin, and the limiting quality of anthropocentric, child-centered pedagogies in early childhood education.

Understanding Decision Making by Families About Youth Football Participation Postconcussion

2020 ◽  
pp. 152483992094525
Author(s):  
Emily Kroshus ◽  
Deborah Bowen ◽  
Douglas Opel ◽  
Sara P. D. Chrisman ◽  
Frederick P. Rivara
Keyword(s):  
Pacific Northwest ◽  
Decision Aid ◽  
Sports Participation ◽  
The United States ◽  
Football Players ◽  
Contact Sport ◽  
Sample Mean ◽  
Youth Football ◽  
The Pacific ◽  
Northwest Region

Many families are concerned about their child’s risk of concussion, and some seek counsel from clinicians about whether or not to return to contact sports participation postinjury. The present study sought to identify factors that parents weight most heavily in forming their preferences regarding whether their child should return to contact sport after recovering from a concussion. Survey data were collected from 568 parents of youth football players (aged 7–14 years) in the Pacific Northwest region of the United States (73% response rate). Approximately two thirds (63%) of parents preferred that their child retire from football after one or two concussions. Multivariable linear regression indicated parents above the sample mean in terms of how strongly they valued football participation preferred their child stop after more concussions than parents below the sample mean (β = .44, standard error [SE] = 0.06, p < .001). Factors endorsed by the most parents as making them “much more likely” to want their child to stop playing football included the belief that their child will experience cognitive issues later in life as a result of concussions (65.0%) and that their child will get another concussion while playing football (43.5%). Within the context of a clinical visit postconcussion, physicians may need to help families clarify their values related to football participation and provide information about the potential outcomes of returning to contact sport. A formalized shared decision aid could help support consistent implementation of this potentially challenging conversation.

Mapping “At Risk” Snow in the Pacific Northwest

2006 ◽  
Vol 7 (5) ◽  
pp. 1164-1171 ◽  
Author(s):  
Anne W. Nolin ◽  
Christopher Daly
Keyword(s):  
At Risk ◽  
Snow Cover ◽  
Pacific Northwest ◽  
Climate Warming ◽  
The United States ◽  
Cold Climate ◽  
Temperature Threshold ◽  
Precipitation Regime ◽  
The Pacific ◽  
Northwest Region

Abstract One of the most visible and widely felt impacts of climate warming is the change (mostly loss) of low-elevation snow cover in the midlatitudes. Snow cover that accumulates at temperatures close to the ice-water phase transition is at greater risk to climate warming than cold climate snowpacks because it affects both precipitation phase and ablation rates. This study maps areas in the Pacific Northwest region of the United States that are potentially at risk of converting from a snow-dominated to a rain-dominated winter precipitation regime, under a climate-warming scenario. A data-driven, climatological approach of snow cover classification is used to reveal these “at risk” snow zones and also to examine the relative frequency of warm winters for the region. For a rain versus snow temperature threshold of 0°C the at-risk snow class covers an area of about 9200 km2 in the Pacific Northwest region and represents approximately 6.5 km3 of water. Many areas of the Pacific Northwest would see an increase in the number of warm winters, but the impacts would likely be concentrated in the Cascade and Olympic Ranges. A number of lower-elevation ski areas could experience negative impacts because of the shift from winter snows to winter rains. The results of this study point to the potential for using existing datasets to better understand the potential impacts of climate warming.

An evaluation ofP-Δ amplification factors in multistorey steel moment resisting frames

1999 ◽  
Vol 26 (5) ◽  
pp. 535-548 ◽  
Author(s):  
R Tremblay ◽  
B Côté ◽  
P Léger
Keyword(s):  
Amplification Factor ◽  
Ground Motions ◽  
Beam Model ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frame ◽  
Dynamic Analyses ◽  
Moment Resisting ◽  
Shear Beam ◽  
Nonlinear Dynamic Analyses ◽  
Shear Beam Model

Three different amplification factors that have been proposed to account for P-Δ effects in the seismic design of multistorey building structures are described and compared. Nonlinear dynamic analyses of a typical 20-storey steel moment resisting frame are carried out under earthquake ground motions typical of eastern and western Canada to evaluate the gravity load effects and to assess the effectiveness of each type of amplification factor in accounting for these effects. All three approaches maintain the ductility demand within the level computed without P-Δ effects, but lateral deformations are generally larger than those obtained neglecting the gravity loads. Nonlinear dynamic analyses are also performed on a shear-beam (stick) model of the same building to examine the possibility of using such simple models for studying the dynamic stability of buildings subjected to ground motions. The shear-beam model does not predict adequately the seismic behaviour of steel moment resisting frames for which P-Δ effects are significant.Key words: ductility, earthquake, ground motion, lateral deformation, moment resisting frame, P-Δ effects, push-over analysis, seismic, shear-beam model, stability coefficient, amplification factor.

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