Effects of Seismic Incident Directionality on Ground Motion Characteristics and Responses of a Single-Mass Bi-Degree-of-Freedom System

2021 ◽  
pp. 2150119
Author(s):  
Jun Gong ◽  
Xudong Zhi ◽  
Feng Fan ◽  
Shizhao Shen ◽  
Da Qaio ◽  
...  
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Propagation Distance ◽  
Degree Of Freedom ◽  
Different Types ◽  
Single Mass ◽  
Motion Characteristics ◽  
The Impact

To investigate the variability of ground motion characteristics (GMC) with the angle of seismic incidence (ASI) and the impact of seismic incident directionality on structural responses, first, a large-scale database of recorded ground motions was used to analyze the causes of GMC variability due to the seismic incident directionality effect (SIDE). Then a single-mass bi-degree-of-freedom system (SM-BDOF-S) with different types of symmetrical sections was selected to explore the influence mechanism of SIDE on the seismic responses. The results illustrated that the GMC has substantial variability with the ASI, which is independent of the earthquake source, propagation distance, and site condition, and exhibits complex random characteristics. Additionally, a classification method for ground motions is proposed based on this GMC variability to establish a criterion for selecting ground motions in seismic analysis considering the SIDE. Moreover, for an SM-BDOF-S, the response spectral plane is proposed to explain the transition behavior of spectral responses that are very similar among different stiffness ratios, but divergent for different types of ground motions. The influence of SIDE on structures is determined by their stiffness and stiffness ratio in the [Formula: see text]- and [Formula: see text]-directions, as well as the type of ground motion.

Situational Breakdowns

2019 ◽  
Author(s):  
Anne Nassauer
Keyword(s):  
United States ◽  
Large Scale ◽  
Contextual Factors ◽  
The United States ◽  
Social Outcomes ◽  
Dynamic Processes ◽  
Collective Decisions ◽  
Different Types ◽  
The Impact

This book provides an account of how and why routine interactions break down and how such situational breakdowns lead to protest violence and other types of surprising social outcomes. It takes a close-up look at the dynamic processes of how situations unfold and compares their role to that of motivations, strategies, and other contextual factors. The book discusses factors that can draw us into violent situations and describes how and why we make uncommon individual and collective decisions. Covering different types of surprise outcomes from protest marches and uprisings turning violent to robbers failing to rob a store at gunpoint, it shows how unfolding situations can override our motivations and strategies and how emotions and culture, as well as rational thinking, still play a part in these events. The first chapters study protest violence in Germany and the United States from 1960 until 2010, taking a detailed look at what happens between the start of a protest and the eruption of violence or its peaceful conclusion. They compare the impact of such dynamics to the role of police strategies and culture, protesters’ claims and violent motivations, the black bloc and agents provocateurs. The analysis shows how violence is triggered, what determines its intensity, and which measures can avoid its outbreak. The book explores whether we find similar situational patterns leading to surprising outcomes in other types of small- and large-scale events: uprisings turning violent, such as Ferguson in 2014 and Baltimore in 2015, and failed armed store robberies.

Changes in mechanisms and intensity of Western U.S. floods, 1960-2013

2021 ◽  
Author(s):  
Jessica Fayne ◽  
Huilin Huang ◽  
Mike Fischella ◽  
Yufei Liu ◽  
Zhaoxin Ban ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Large Scale ◽  
Critical Factor ◽  
Flood Frequency ◽  
Atmospheric Rivers ◽  
Convective Storms ◽  
Noticeable Increase ◽  
Complex Interactions ◽  
Different Types ◽  
The Impact

<p>Extreme precipitation, a critical factor in flooding, has selectively increased with warmer temperatures in the Western U.S. Despite this, the streamflow measurements have captured no noticeable increase in large-scale flood frequency or intensity. As flood studies have mostly focused on specific flood events in particular areas, analyses of large-scale floods and their changes have been scarce. For floods during 1960-2013, we identify six flood generating mechanisms (FGMs) that are prominent across the Western U.S., including atmospheric rivers and non-atmospheric rivers, monsoons, convective storms, radiation-driven snowmelt, and rain-on-snow, in order to identify to what extent different types of floods are changing based on the dominant FGM. The inconsistency between extreme precipitation and lack of flood increase suggests that the impact of climate change on flood risk has been modulated by hydro-meteorological and physiographic processes such as sharp increases in temperature that drive increased evapotranspiration and decreased soil moisture. Our results emphasize the importance of FGMs in understanding the complex interactions of flooding and climatic changes and explain the broad spatiotemporal changes that have occurred across the vast Western U.S. for the past 50 years.</p>

Conditioned Simulation of Ground-Motion Time Series at Uninstrumented Sites Using Gaussian Process Regression

2021 ◽  
Author(s):  
Aidin Tamhidi ◽  
Nicolas Kuehn ◽  
S. Farid Ghahari ◽  
Arthur J. Rodgers ◽  
Monica D. Kohler ◽  
...  
Keyword(s):  
Time Series ◽  
Gaussian Process ◽  
Ground Motion ◽  
San Francisco ◽  
Earthquake Engineering ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Free Field ◽  
Gaussian Process Regression ◽  
Motion Time

ABSTRACT Ground-motion time series are essential input data in seismic analysis and performance assessment of the built environment. Because instruments to record free-field ground motions are generally sparse, methods are needed to estimate motions at locations with no available ground-motion recording instrumentation. In this study, given a set of observed motions, ground-motion time series at target sites are constructed using a Gaussian process regression (GPR) approach, which treats the real and imaginary parts of the Fourier spectrum as random Gaussian variables. Model training, verification, and applicability studies are carried out using the physics-based simulated ground motions of the 1906 Mw 7.9 San Francisco earthquake and Mw 7.0 Hayward fault scenario earthquake in northern California. The method’s performance is further evaluated using the 2019 Mw 7.1 Ridgecrest earthquake ground motions recorded by the Community Seismic Network stations located in southern California. These evaluations indicate that the trained GPR model is able to adequately estimate the ground-motion time series for frequency ranges that are pertinent for most earthquake engineering applications. The trained GPR model exhibits proper performance in predicting the long-period content of the ground motions as well as directivity pulses.

scholarly journals The 30 October 2020 Samos (Eastern Aegean Sea) Earthquake: effects of source rupture, path and local-site conditions on the observed and simulated ground motions

2021 ◽  
Author(s):  
Aybige Akinci ◽  
Daniele Cheloni ◽  
AHMET ANIL DINDAR
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Ground Motions ◽  
Aegean Sea ◽  
Peak Ground Velocity ◽  
Ground Shaking ◽  
Local Site ◽  
Eastern Aegean ◽  
Motion Characteristics ◽  
Eastern Aegean Sea

Abstract On 30 October 2020 a MW 7.0 earthquake occurred in the eastern Aegean Sea, between the Greek island of Samos and Turkey’s Aegean coast, causing considerable seismic damage and deaths, especially in the Turkish city of Izmir, approximately 70 km from the epicenter. In this study, we provide a detailed description of the Samos earthquake, starting from the fault rupture to the ground motion characteristics. We first use Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data to constrain the source mechanisms. Then, we utilize this information to analyze the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and spectral pseudo-accelerations. Modelling of geodetic data shows that the Samos earthquake ruptured a NNE-dipping normal fault located offshore north of Samos, with up to 2.5-3 m of slip and an estimated geodetic moment of 3.3 ⨯ 1019 Nm (MW 7.0). Although low PGA were induced by the earthquake, the ground shaking was strongly amplified in Izmir throughout the alluvial sediments. Structural damage observed in Izmir reveals the potential of seismic risk due to the local site effects. To better understand the earthquake characteristics, we generated and compared stochastic strong ground motions with the observed ground motion parameters as well as the ground motion prediction equations (GMPEs), exploring also the efficacy of the region-specific parameters which may be improved to better predict the expected ground shaking from future large earthquakes in the region.

scholarly journals InSAR Greece with Parallelized Persistent Scatterer Interferometry: A National Ground Motion Service for Big Copernicus Sentinel-1 Data

2020 ◽  
Vol 12 (19) ◽  
pp. 3207
Author(s):  
Ioannis Papoutsis ◽  
Charalampos Kontoes ◽  
Stavroula Alatza ◽  
Alexis Apostolakis ◽  
Constantinos Loupasakis
Keyword(s):  
Time Series ◽  
Ground Motion ◽  
Large Scale ◽  
Persistent Scatterer Interferometry ◽  
Persistent Scatterers ◽  
Processing Chain ◽  
Persistent Scatterer ◽  
Basin Scale ◽  
Wide Range ◽  
The Impact

Advances in synthetic aperture radar (SAR) interferometry have enabled the seamless monitoring of the Earth’s crust deformation. The dense archive of the Sentinel-1 Copernicus mission provides unprecedented spatial and temporal coverage; however, time-series analysis of such big data volumes requires high computational efficiency. We present a parallelized-PSI (P-PSI), a novel, parallelized, and end-to-end processing chain for the fully automated assessment of line-of-sight ground velocities through persistent scatterer interferometry (PSI), tailored to scale to the vast multitemporal archive of Sentinel-1 data. P-PSI is designed to transparently access different and complementary Sentinel-1 repositories, and download the appropriate datasets for PSI. To make it efficient for large-scale applications, we re-engineered and parallelized interferogram creation and multitemporal interferometric processing, and introduced distributed implementations to best use computing cores and provide resourceful storage management. We propose a new algorithm to further enhance the processing efficiency, which establishes a non-uniform patch grid considering land use, based on the expected number of persistent scatterers. P-PSI achieves an overall speed-up by a factor of five for a full Sentinel-1 frame for processing in a 20-core server. The processing chain is tested on a large-scale project to calculate and monitor deformation patterns over the entire extent of the Greek territory—our own Interferometric SAR (InSAR) Greece project. Time-series InSAR analysis was performed on volumes of about 12 TB input data corresponding to more than 760 Single Look Complex Sentinel-1A and B images mostly covering mainland Greece in the period of 2015–2019. InSAR Greece provides detailed ground motion information on more than 12 million distinct locations, providing completely new insights into the impact of geophysical and anthropogenic activities at this geographic scale. This new information is critical to enhancing our understanding of the underlying mechanisms, providing valuable input into risk assessment models. We showcase this through the identification of various characteristic geohazard locations in Greece and discuss their criticality. The selected geohazard locations, among a thousand, cover a wide range of catastrophic events including landslides, land subsidence, and structural failures of various scales, ranging from a few hundredths of square meters up to the basin scale. The study enriches the large catalog of geophysical related phenomena maintained by the GeObservatory portal of the Center of Earth Observation Research and Satellite Remote Sensing BEYOND of the National Observatory of Athens for the opening of new knowledge to the wider scientific community.

Predictive Equations to Quantify the Impact of Spectral Matching on Ground Motion Characteristics

2016 ◽  
Vol 32 (1) ◽  
pp. 125-142 ◽  
Author(s):  
Clinton Carlson ◽  
Dimitrios Zekkos ◽  
Adda Athanasopoulos-Zekkos
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Peak Ground Velocity ◽  
Spectral Matching ◽  
Predictive Equations ◽  
Earthquake Scenarios ◽  
Cumulative Absolute Velocity ◽  
Motion Characteristics ◽  
The Impact

Spectral matching, the process of modifying a seed acceleration time history in intensity and frequency content until its acceleration response spectrum matches a target spectrum, is used extensively in practice. Predictive equations that quantify the impact of spectral matching on the peak ground velocity, peak ground displacement, Arias intensity, and cumulative absolute velocity of a scaled seed time history have been developed and validated on the basis of thousands of matched motions, three different earthquake scenarios, and numerous target spectra. It is found that spectral mismatch is the most critical factor affecting the changes in ground motion characteristics. The technique used for modification (e.g., time domain or frequency domain) is in many cases not critical. Based on the results, recommendations in order to minimize the impact of matching on the ground motion characteristics are provided.

Exploring the Proximity of Ground-Motion Models Using High-Dimensional Visualization Techniques

2010 ◽  
Vol 26 (4) ◽  
pp. 1117-1138 ◽  
Author(s):  
Frank Scherbaum ◽  
Nicolas M. Kuehn ◽  
Matthias Ohrnberger ◽  
Andreas Koehler
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
High Dimensional ◽  
Logic Tree ◽  
Motion Models ◽  
Metric Set ◽  
Motion Characteristics ◽  
Visualization Techniques ◽  
Ground Motion Models

Logic trees have become a popular tool to capture epistemic uncertainties in seismic hazard analysis. They are commonly used by assigning weights to models on a purely descriptive basis (nominal scale). This invites the creation of unintended inconsistencies regarding the weights on the corresponding hazard curves. On the other hand, for human experts it is difficult to confidently express degrees-of-beliefs in particular numerical values. Here we demonstrate for ground-motion models how the model and the value-based perspectives can be partially reconciled by using high-dimensional information-visualization techniques. For this purpose we use Sammon's (1969) mapping and self-organizing mapping to project ground-motion models onto a two-dimensional map (an ordered metric set). Here they can be evaluated jointly according to their proximity in predicting similar ground motions, potentially making the assignment of logic tree weights consistent with their ground motion characteristics without having to abandon the model-based perspective.

Effect of Ground Motion Modification Technique on Seismic Geotechnical Engineering Analyses

2012 ◽  
Vol 28 (4) ◽  
pp. 1643-1661 ◽  
Author(s):  
Dimitrios Zekkos ◽  
Clinton Carlson ◽  
Ahmed Nisar ◽  
Stephanie Ebert
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
A Priori ◽  
Earthquake Scenarios ◽  
Local Site ◽  
Intensity Parameters ◽  
Target Spectrum ◽  
Modification Technique ◽  
The Time Domain ◽  
The Impact

Ground motion modification (or spectral matching) has been criticized, but has many appealing characteristics and is widely used in practice. Modification of ground motions can be performed in either the time domain or the frequency domain. Depending on the choice of modification technique, modified ground motions can be significantly different from each other as well as from the original ground motion. This paper studies the impact of these differences on seismic geotechnical analyses for two different site profiles using two earthquake scenarios and a total of 20 ground motions. This study shows that the final results are influenced by many factors such as the original (seed) ground motion, the target spectrum, and the local site conditions, in addition to the ground motion modification technique used. The results also show that while both techniques can significantly modify the original ground motion, neither technique is consistently more conservative than the other. Therefore, a general conclusion that a particular technique results in ground motions that yield the largest intensity parameters cannot be made a priori.

scholarly journals Dynamic Damage Mechanism and Seismic Fragility Analysis of an Aqueduct Structure

2021 ◽  
Vol 11 (24) ◽  
pp. 11709
Author(s):  
Xinyong Xu ◽  
Xuhui Liu ◽  
Li Jiang ◽  
Mohd Yawar Ali Khan
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Large Scale ◽  
Seismic Analysis ◽  
Fragility Curves ◽  
Limit State ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Exceedance Probability ◽  
Computation Efficiency

The Concrete Damaged Plasticity (CDP) constitutive is introduced to study the dynamic failure mechanism and the law of damage development to the aqueduct structure during the seismic duration using a large-scale aqueduct structure from the South-to-North Water Division Project (SNWDP) as a research object. Incremental dynamic analysis (IDA) and multiple stripe analysis (MSA) seismic fragility methods are introduced. The spectral acceleration is used as the scale of ground motion record intensity measure (IM), and the aqueduct pier top offset ratio quantifies the limit of structural damage measure (DM). The aqueduct structure’s seismic fragility evaluation curves are constructed with indicators of different seismic intensity measures to depict the damage characteristics of aqueduct structures under different seismic intensities through probability. The results show that penetrating damage is most likely to occur on both sides of the pier cap and around the pier shaft in the event of a rare earthquake, followed by the top of the aqueduct body, which requires the greatest care during an earthquake. The results of two fragility analysis methodologies reveal that the fragility curves are very similar. The aqueduct structure’s first limit state level (LS1) is quite steep and near the vertical line, indicating that maintaining the excellent condition without damage in the seismic analysis will be challenging. Except for individual results, the overall fragility results are in good agreement, and the curve change rule is the same. The exceedance probability in the case of any ground motion record IM may be estimated using only two factors when using the MSA approach, and the computation efficiency is higher. The study of seismic fragility analysis methods in this paper can provide a reference for the seismic safety evaluation of aqueducts and similar structures.

Sign in / Sign up

Export Citation Format

Share Document