Ashly Cabas

Ashly Cabas
North Carolina State University | NCSU · Department of Civil, Construction, and Environmental Engineering

Doctor of Philosophy

About

35
Publications
4,890
Reads
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145
Citations
Citations since 2017
33 Research Items
145 Citations
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20172018201920202021202220230102030405060
20172018201920202021202220230102030405060
20172018201920202021202220230102030405060

Publications

Publications (35)
Article
Full-text available
One of the most commonly used parameters to describe seismic attenuation is the high-frequency spectral decay parameter Kappa (κr), yet the physics behind it remain little understood. A better understanding of potential factors that lead to large scatter in estimated values of κr constitutes a critical need for ground-motion modeling and seismic ha...
Article
Full-text available
In this article, we compare field estimates of near-surface attenuation, as captured by site-specific κ-values (i.e., κ0) with laboratory-based estimates of minimum shear-strain damping (ξmin). We propose models for ξmin based on κ0 measured at selected stations of the KiK-net database, which are found to be generally larger than low-strain damping...
Article
Full-text available
Input motions used in seismic site response analyses are commonly selected based on similarities between the shear wave velocity (VS) at the recording station, and the reference depth at the site of interest (among other aspects such as the intensity of the expected ground motion). This traditional approach disregards the influence of the attenuati...
Conference Paper
Full-text available
Accurately constraining site response analysis (SRA) results and their associated uncertainty is a key aspect of the seismic design process. The variability and uncertainty in SRA results are typically attributed to the uncertainties in the dynamic properties of the materials, the selected input motions, and intrinsic model assumptions. This study...
Conference Paper
This study investigates the challenges associated with selecting ground motions representative of the site-specific seismic hazards in two major U.S. cities located in different tectonic environments: Seattle and Boston. Seattle is in an active tectonic region, with seismic hazard contributions from crustal and subduction events. Boston is located...
Article
This article presents a ground motion database for California and its close surroundings (i.e. areas near the border in Nevada, Oregon, and Arizona) from earthquakes between 1999 and 2021. This data set includes events with magnitudes larger than 3.2 and focal depths less than 40 km, and it is available on DesignSafe. Ground motion records and even...
Article
The Mw 7.2 Nippes, Haiti, earthquake occurred on 14 August 2021 in Haiti’s southwest peninsula and in the midst of significant social, economic, and political crises. A hybrid reconnaissance mission (i.e., combined remote and field investigation) was coordinated to document damage to the built environment after the event. This article evaluates two...
Conference Paper
Improving the seismic performance of pipelines is fundamental to achieving resiliency of urban environments against extreme natural events. The vulnerability of pipelines is inevitably associated with their exposure to regional and local geohazards. Seismic hazard assessments of pipelines are uniquely challenged by varying local soil conditions, as...
Article
Full-text available
One of the fundamental decisions when performing one-dimensional (1D) site response analyses (SRA) involves the selection of the depth and dynamic properties of the elastic halfspace (EHS). This boundary condition assumes linear and homogenous material underlying the soil column for an infinite depth. This assumption implies that waves refracted in...
Chapter
Characterizing and quantifying the effects of local soil conditions are essential for site-specific seismic hazard assessment and site response analysis. The high-frequency spectral decay parameter \({\kappa }_{r}\) and its site-specific component, \({\kappa }_{0}\), have gained popularity due to their abilities to characterize near-surface attenua...
Chapter
Local soil conditions influence earthquake-induced ground shaking and deformation; a phenomenon known as site effects. The latter correlate with the concentration of damages to the built environment in areas prone to ground motion (GM) amplification. However, the characterization of geotechnical parameters affecting spatially varying earthquake GMs...
Conference Paper
Kappa (κr), the high-frequency spectral decay parameter, has been gaining popularity in the engineering seismology field for more than forty years, but it was not until recently that κr has been used for geotechnical earthquake engineering applications. For instance, κr has been used in site-specific seismic hazard analysis and site response analys...
Article
Earthquake ground motions (GMs) may display distinct characteristics in all directions within the horizontal plane. However, the causes of GM polarization are still not fully understood. Structural designs use maximum rotated intensity measures (IMRotD100) to accommodate variations of the GM with orientation, but the orientation associated with IMR...
Article
Full-text available
The 2018 M w 7.1 Anchorage, Alaska, earthquake is one of the largest earthquakes to strike near a major US city since the 1994 Northridge earthquake. The significance of this event motivated reconnaissance efforts to thoroughly document damage to the built environment. This article presents the spatial variability of ground motion intensity and its...
Article
Full-text available
Soil nonlinear behavior is often triggered in soft sedimentary deposits subjected to strong ground shaking and has led to catastrophic damage to civil infrastructure in many past earthquakes. Nonlinear behavior in soils is associated with large shear strains, increased material damping ratio and reduced stiffness. However, most investigations of th...
Conference Paper
Seismic slope stability analyses are crucial for assessing the seismic performance of earthen structures and natural slopes. Input ground motions are often important components of such analyses and represent one of the main sources of variability in site response. Most studies on seismic stability analyses have been conducted using shallow crustal...
Conference Paper
The moment magnitude (Mw) 7.1 Anchorage, Alaska, earthquake on November 30, 2018 is one of the largest earthquakes to strike near a major U.S. city since the 1994 Northridge earthquake. No fatalities were reported, but the earthquake caused widespread power outages, structural damage to residential buildings, damage to roadways and railways, and gr...
Thesis
Full-text available
The definition of hazard-consistent ground motions for seismic design has been an active area of research in the past few decades. With the advancements in computing power we have taken giant steps in performance based seismic design (PBSD). At the heart of PBSD is performing non-linear response history analysis to verify the performance of a struc...
Conference Paper
There have been significant advances in the prediction of liquefaction triggering since the late 1960s. However, research to date has not provided consensus on preferred practices to estimate the consequences of liquefaction and quantify the large uncertainties involved. The severity of liquefaction vividly displayed during the 1995 Kobe earthquake...
Conference Paper
Borehole array data provide us with the opportunity to study the effects of near-surface soil conditions on ground motions. These data are also used to validate numerical models that aim to represent the behavior of soils. In this study, ground motion data from the instrumented borehole arrays of the Garner Valley in Southern California are analyze...
Conference Paper
Accurately constraining site response analysis (SRA) results and their associated uncertainty is a key aspect of the seismic design process. The variability and uncertainty in SRA results are typically attributed to the uncertainties in the dynamic properties of the materials, the selected input motions, and intrinsic model assumptions. This study...
Article
Full-text available
Input motions used in seismic site response analyses are commonly selected based on similarities between the shear wave velocity (Vs) at the recording station, and the reference depth at the site of interest (among other aspects such as the intensity of the expected ground motion). This traditional approach disregards the influence of the attenuati...
Conference Paper
Full-text available
Site response analyses (SRA) provide a means to assess the seismic wave propagation phenomenon in shallow deposits and capture its influence on ground motions. One of the key model assumptions in SRA involves the characterization of the attenuation at the site. Typical damping models are developed by testing small-scale soil samples in the laborato...
Conference Paper
One of the fundamental decisions when conducting an equivalent linear site response analysis involves the determination of the depth and characteristics of the elastic half-space (EHS). This boundary condition is usually defined at a horizon sufficiently stiff such that no strong impedance contrasts will be found below this depth. The assumption of...

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