Amplification of Rocking Due to Horizontal Ground Motion

2012 ◽  
Vol 28 (4) ◽  
pp. 1405-1421 ◽  
Author(s):  
Matthew J. DeJong
Keyword(s):  
Ground Motion ◽  
Energy Input ◽  
Ground Motions ◽  
Statistical Assessment ◽  
Rocking Block ◽  
Real Earthquake ◽  
Horizontal Ground Motion ◽  
Assessment Procedures ◽  
Earthquake Data ◽  
Rocking Response

This paper addresses the fundamental behavior of rocking structures by investigating the rate of energy input due to horizontal ground motion. This perspective indicates that the assumption of initial at-rest conditions may be inappropriate, and identifies ground motions which cause ‘rocking resonance’ for various constraints. Furthermore, the ability of multiple impulses to either reduce or amplify the rocking response is demonstrated, and motivates the use of statistical assessment procedures to predict rocking stability during earthquakes. In this context, past earthquake data is used to generate an array of synthetic earthquakes of a given intensity which are applied to determine the overturning probability of the rocking block. The results emphasize the time dependence of the rocking response. Finally, simulation of the rocking response to real earthquake records confirms that multiple impulse rocking amplification may be significant.

Relations between MaxRotD50 and Some Horizontal Components of Ground-Motion Intensity Used in Practice

2021 ◽  
Author(s):  
Alan Poulos ◽  
Eduardo Miranda
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Ground Motions ◽  
Geometric Mean ◽  
The Other ◽  
Horizontal Projection ◽  
Site Class ◽  
Engineering Research ◽  
Natural Logarithm ◽  
Horizontal Ground Motion

ABSTRACT The most commonly used intensity measure of ground motion in earthquake engineering is the 5% damped spectral ordinate, which varies in different directions. Several different measures have been proposed over the years to combine the intensity of the two horizontal recorded ground motions to derive ground-motion models as well as for design purposes. This study provides the relation to seven previously used measures of horizontal ground motion with respect to a recently proposed orientation-independent measure of horizontal ground-motion intensity referred to as MaxRotD50. This new measure of horizontal intensity is defined as the median value of the maximum spectral ordinate of two orthogonal directions computed for all possible nonredundant orientations. The relations are computed using 5065 pairs of horizontal ground motions taken from the database of ground motions recorded in shallow crustal earthquakes in active tectonic regions developed as part of the Pacific Earthquake Engineering Research Center’s Next Generation Attenuation-West2 project. Empirically derived period-dependent relations are presented for three quantities that permit transforming any of the seven other definitions of horizontal ground-motion intensity to MaxRotD50, namely, (1) geometric mean of the ratio of MaxRotD50 to any of the seven other measures of intensities, (2) standard deviation of the natural logarithm of the ratio of MaxRotD50 to any of the seven other measures of intensities, and (3) the correlation between the natural logarithm of the ratio of MaxRotD50 to the other measures of intensities and the natural logarithm of the other measure of intensity. In addition, the influence of site class at the recording station, earthquake magnitude, and distance to the horizontal projection of the rupture is examined on the geometric mean of the ratio of MaxRotD50 to the median intensity of all nonredundant orientations (i.e., RotD50), showing negligible influence of site class and only a relatively small influence of magnitude and distance.

Turkey-Adjusted NGA-W1 Horizontal Ground Motion Prediction Models

2016 ◽  
Vol 32 (1) ◽  
pp. 75-100 ◽  
Author(s):  
Zeynep Gülerce ◽  
Bahadır Kargoığlu ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Prediction Models ◽  
Ground Motions ◽  
Site Amplification ◽  
Motion Prediction ◽  
Ground Motion Prediction ◽  
Data Set ◽  
Horizontal Ground Motion ◽  
Strong Ground

The objective of this paper is to evaluate the differences between the Next Generation Attenuation: West-1 (NGA-W1) ground motion prediction models (GMPEs) and the Turkish strong ground motion data set and to modify the required pieces of the NGA-W1 models for applicability in Turkey. A comparison data set is compiled by including strong motions from earthquakes that occurred in Turkey and earthquake metadata of ground motions consistent with the NGA-W1 database. Random-effects regression is employed and plots of the residuals are used to evaluate the differences in magnitude, distance, and site amplification scaling. Incompatibilities between the NGA-W1 GMPEs and Turkish data set in small-to-moderate magnitude, large distance, and site effects scaling are encountered. The NGA-W1 GMPEs are modified for the misfit between the actual ground motions and the model predictions using adjustments functions. Turkey-adjusted NGA-W1 models are compatible with the regional strong ground motion characteristics and preserve the well-constrained features of the global models.

Seismic assessment of a cable-stayed arch bridge under three-component orthotropic earthquake excitation

2020 ◽  
pp. 136943322094875 ◽  
Author(s):  
Salar Farahmand-Tabar ◽  
Majid Barghian
Keyword(s):  
Ground Motion ◽  
Numerical Study ◽  
Epicentral Distance ◽  
Ground Motions ◽  
Dynamic Responses ◽  
Earthquake Excitation ◽  
Arch Bridge ◽  
Stay Cables ◽  
Horizontal Ground Motion ◽  
Ground Motion Records

The occurred damages during the past significant earthquakes have proved that vertical seismic excitation has tremendous effect on bridges. Three-component earthquake excitations are preferred to resemble the earthquakes. In this article, a cable-stayed arch bridge, a new type of bridge with the hybrid system of half-through arch and stay-cables, was analyzed under a set of different earthquake excitations (more than 21 ground motion records). Both vertical and horizontal components of the ground motions were considered to act simultaneously at the bridge supports. By using different three-component earthquake excitations, the dynamic responses of the bridge, including the displacements and accelerations of the main parts of the bridge, were obtained. The effects of various parameters such as soil type, epicentral distance, spatial variation of the ground motions, and dimensional variation of the structure were investigated. The results of the numerical study indicate that the cable-stayed arch bridge subjected to both horizontal and vertical components of earthquakes are more vulnerable than those subjected to horizontal ground motion only.

scholarly journals Orientation effects of horizontal seismic components on longitudinal reinforcement in R/C frame elements

2012 ◽  
Vol 12 (1) ◽  
pp. 1-10 ◽  
Author(s):  
K. G. Kostinakis ◽  
A. M. Athanatopoulou ◽  
I. E. Avramidis
Keyword(s):  
Ground Motion ◽  
Cross Sections ◽  
Linear Response ◽  
Ground Motions ◽  
Longitudinal Reinforcement ◽  
Analysis And Design ◽  
History Analysis ◽  
Response History Analysis ◽  
Internal Forces ◽  
Horizontal Ground Motion

Abstract. The present paper investigates the influence of the orientation of recorded horizontal ground motion components on the longitudinal reinforcement of R/C frame elements within the context of linear response history analysis. For this purpose, three single-story buildings are analyzed and designed for 13 recorded bi-directional ground motions applied along the horizontal structural axes. The analysis and design is performed for several orientations of the recording angle of the horizontal seismic components. For each orientation the longitudinal reinforcement at all critical cross sections is calculated using four methods of selecting the set of internal forces needed to compute the required reinforcement. The results show that the reinforcement calculated by three of the applied methods is significantly affected by the orientation of the recording angle of ground motion, while the fourth one leads to results which are independent of the orientation of the recording angle.

Investigations on the Seismic Responses of Structures with a Suspended Mass

2016 ◽  
Vol 16 (02) ◽  
pp. 1550066
Author(s):  
Wenhui Wei ◽  
Aoxiong Dai ◽  
Yong-Lin Pi ◽  
Mark Andrew Bradford
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Power Transmission ◽  
Ground Motions ◽  
Equations Of Motion ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Scaled Model ◽  
High Voltage Direct Current ◽  
Horizontal Ground Motion

This paper presents the shaking table tests and an analytical study of structures with a suspended mass under coupled horizontal and tilting ground motions (CHT) caused by an earthquake. Shaking table tests of a 1:10 scaled model for a converter valve hall with a suspended mass in a high-voltage direct current electric power transmission station are carried out. The equations of motion for the structure, including the influence of the rotary inertia of the suspended mass, are derived. The responses of the model to different ground motions during an earthquake are investigated. It is found that the tilting ground motion plays a significant role in predicting the seismic response of the structure, and it needs to be considered in association with the horizontal ground motion. The response of the structure with a suspended mass to CHT ground motion is much larger than that to horizontal ground motion. The possibility of replacing the steel cables with springs as the suspending components is also investigated, and the spring is shown not to influence the acceleration and displacement responses greatly, but it significantly reduces the tension in the suspending components. Therefore, when a suspended mass is used as a mass-pendulum mitigation system, it is more advantageous to use springs or members having a low axial rigidity as the suspending components. In addition, the effects of the length of the cables and springs on the seismic response of the model with a suspended mass are also explored. It is found that the shorter the cables (or springs), the better the mitigation effects of the suspended mass on the main structure.

NGA-West2 Models for Ground Motion Directionality

2014 ◽  
Vol 30 (3) ◽  
pp. 1285-1300 ◽  
Author(s):  
Shrey K. Shahi ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Response Spectra ◽  
Engineering Research ◽  
The Pacific ◽  
Horizontal Ground Motion ◽  
Motion Directionality ◽  
The Relationship

The NGA-West2 research program, coordinated by the Pacific Earthquake Engineering Research Center (PEER), is a major effort to produce refined models for predicting ground motion response spectra. This study presents new models for ground motion directionality developed as part of that project. Using a database of recorded ground motions, empirical models have been developed for a variety of quantities related to direction-dependent spectra. A model is proposed for the maximum spectral acceleration observed in any orientation of horizontal ground motion shaking ( Sa RotD100), which is formulated as a multiplicative factor to be coupled with the NGA-West2 models that predict the median spectral accelerations over all orientations ( Sa RotD50). Models are also proposed for the distribution of orientations of the Sa RotD100 value, relative to the fault and the relationship between Sa RotD100 orientations at differing periods. Discussion is provided regarding how these results can be applied to perform seismic hazard analysis and compute realistic target spectra conditioned on different parameters.

A subset of CyberShake ground-motion time series for response-history analysis

2021 ◽  
pp. 875529302098197
Author(s):  
Jack W Baker ◽  
Sanaz Rezaeian ◽  
Christine A Goulet ◽  
Nicolas Luco ◽  
Ganyu Teng
Keyword(s):  
Time Series ◽  
Los Angeles ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Motion Time ◽  
History Analysis ◽  
Response History Analysis ◽  
Simulated Ground Motions

This manuscript describes a subset of CyberShake numerically simulated ground motions that were selected and vetted for use in engineering response-history analyses. Ground motions were selected that have seismological properties and response spectra representative of conditions in the Los Angeles area, based on disaggregation of seismic hazard. Ground motions were selected from millions of available time series and were reviewed to confirm their suitability for response-history analysis. The processes used to select the time series, the characteristics of the resulting data, and the provided documentation are described in this article. The resulting data and documentation are available electronically.

Ground-motion model for subduction earthquakes in northern South America

2021 ◽  
pp. 875529302110275
Author(s):  
Carlos A Arteta ◽  
Cesar A Pajaro ◽  
Vicente Mercado ◽  
Julián Montejo ◽  
Mónica Arcila ◽  
...  
Keyword(s):  
South America ◽  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Motion Prediction ◽  
Depth Range ◽  
Ground Motion Prediction ◽  
Natural Period ◽  
Nazca Plate ◽  
Northern South America

Subduction ground motions in northern South America are about a factor of 2 smaller than the ground motions for similar events in other regions. Nevertheless, historical and recent large-interface and intermediate-depth slab earthquakes of moment magnitudes Mw = 7.8 (Ecuador, 2016) and 7.2 (Colombia, 2012) evidenced the vast potential damage that vulnerable populations close to earthquake epicenters could experience. This article proposes a new empirical ground-motion prediction model for subduction events in northern South America, a regionalization of the global AG2020 ground-motion prediction equations. An updated ground-motion database curated by the Colombian Geological Survey is employed. It comprises recordings from earthquakes associated with the subduction of the Nazca plate gathered by the National Strong Motion Network in Colombia and by the Institute of Geophysics at Escuela Politécnica Nacional in Ecuador. The regional terms of our model are estimated with 539 records from 60 subduction events in Colombia and Ecuador with epicenters in the range of −0.6° to 7.6°N and 75.5° to 79.6°W, with Mw≥4.5, hypocentral depth range of 4 ≤  Zhypo ≤ 210 km, for distances up to 350 km. The model includes forearc and backarc terms to account for larger attenuation at backarc sites for slab events and site categorization based on natural period. The proposed model corrects the median AG2020 global model to better account for the larger attenuation of local ground motions and includes a partially non-ergodic variance model.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

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