An Analytical Method for Elastic Seismic Response of Structures Considering the Effect of Ground Motion Duration

The response to earthquake ground motion is composed of three basic elements, namely, amplitude, frequency, and duration. The seismic response of a structure is controlled by the particular combination of these three elements. The seismic response spectra reflect the earthquake ground motion’s frequency-domain features and provide the maximum response amplitude of a single-degree-of-freedom system to a given earthquake ground motion but do not consider the duration factor. However, the analysis of post-earthquake damage shows that the seismic response duration has a strong impact on the damage to structures. Therefore, it is necessary to develop a simple and practical analytical method to account for the seismic response duration. The present study was conducted based on the response spectra theory. We introduce an analytical method of elastic seismic response, which considers its duration by adding the time-domain dimension of earthquakes. The time-domain spectral matrix is used to solve the time-dependent seismic response through the vibration mode decomposition method. The time-domain vibration mode decomposition reaction spectrum not only takes into account the maximum seismic reaction of each vibration mode but also considers the seismic reaction of different vibration modes occurring at the same time, at each moment. The dynamic time duration of the structure’s seismic reaction is quantified by the time-domain seismic reaction spectrum to obtain a more accurate analysis method for the seismic reaction of the structure.

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The Earthquake Ground Motion and Response Spectra Design for Sleman, Yogyakarta, Indonesia with Probabilistic Seismic Hazard Analysis and Spectral Matching in Time Domain

American Journal of Civil Engineering ◽

10.11648/j.ajce.20160406.15 ◽

2016 ◽

Vol 4 (6) ◽

pp. 298

Author(s):

Lalu Makrup

Keyword(s):

Seismic Hazard ◽

Ground Motion ◽

Time Domain ◽

Hazard Analysis ◽

Response Spectra ◽

Probabilistic Seismic Hazard Analysis ◽

Seismic Hazard Analysis ◽

Earthquake Ground Motion ◽

Probabilistic Seismic Hazard ◽

Spectral Matching

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Seismic rocking effects on a mine tower under induced and natural earthquakes

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00221-7 ◽

2021 ◽

Vol 21 (2) ◽

Author(s):

Piotr Adam Bońkowski ◽

Juliusz Kuś ◽

Zbigniew Zembaty

Keyword(s):

Seismic Response ◽

Ground Motion ◽

Ground Surface ◽

Tall Buildings ◽

Earthquake Ground Motion ◽

Seismic Action ◽

Seismic Effects ◽

Copper Ore ◽

Rotational Components ◽

Natural Earthquakes

AbstractRecent research in engineering seismology demonstrated that in addition to three translational seismic excitations along x, y and z axes, one should also consider rotational components about these axes when calculating design seismic loads for structures. The objective of this paper is to present the results of a seismic response numerical analysis of a mine tower (also called in the literature a headframe or a pit frame). These structures are used in deep mining on the ground surface to hoist output (e.g. copper ore or coal). The mine towers belong to the tall, slender structures, for which rocking excitations may be important. In the numerical example, a typical steel headframe 64 m high is analysed under two records of simultaneous rocking and horizontal seismic action of an induced mine shock and a natural earthquake. As a result, a complicated interaction of rocking seismic effects with horizontal excitations is observed. The contribution of the rocking component may sometimes reduce the overall seismic response, but in most cases, it substantially increases the seismic response of the analysed headframe. It is concluded that in the analysed case of the 64 m mining tower, the seismic response, including the rocking ground motion effects, may increase up to 31% (for natural earthquake ground motion) or even up to 135% (for mining-induced, rockburst seismic effects). This means that not only in the case of the design of very tall buildings or industrial chimneys but also for specific yet very common structures like mine towers, including the rotational seismic effects may play an important role.

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Selection of random vibration theory procedures for the NGA-East project and ground-motion modeling

Earthquake Spectra ◽

10.1177/87552930211019052 ◽

2021 ◽

Vol 37 (1_suppl) ◽

pp. 1420-1439

Author(s):

Albert R Kottke ◽

Norman A Abrahamson ◽

David M Boore ◽

Yousef Bozorgnia ◽

Christine A Goulet ◽

...

Keyword(s):

Ground Motion ◽

Time Domain ◽

Random Vibration ◽

Amplitude Spectrum ◽

Motion Modeling ◽

Peak Response ◽

Vibration Theory ◽

Random Vibration Theory ◽

The Time Domain ◽

The Impact

Traditional ground-motion models (GMMs) are used to compute pseudo-spectral acceleration (PSA) from future earthquakes and are generally developed by regression of PSA using a physics-based functional form. PSA is a relatively simple metric that correlates well with the response of several engineering systems and is a metric commonly used in engineering evaluations; however, characteristics of the PSA calculation make application of scaling factors dependent on the frequency content of the input motion, complicating the development and adaptability of GMMs. By comparison, Fourier amplitude spectrum (FAS) represents ground-motion amplitudes that are completely independent from the amplitudes at other frequencies, making them an attractive alternative for GMM development. Random vibration theory (RVT) predicts the peak response of motion in the time domain based on the FAS and a duration, and thus can be used to relate FAS to PSA. Using RVT to compute the expected peak response in the time domain for given FAS therefore presents a significant advantage that is gaining traction in the GMM field. This article provides recommended RVT procedures relevant to GMM development, which were developed for the Next Generation Attenuation (NGA)-East project. In addition, an orientation-independent FAS metric—called the effective amplitude spectrum (EAS)—is developed for use in conjunction with RVT to preserve the mean power of the corresponding two horizontal components considered in traditional PSA-based modeling (i.e., RotD50). The EAS uses a standardized smoothing approach to provide a practical representation of the FAS for ground-motion modeling, while minimizing the impact on the four RVT properties ( zeroth moment, [Formula: see text]; bandwidth parameter, [Formula: see text]; frequency of zero crossings, [Formula: see text]; and frequency of extrema, [Formula: see text]). Although the recommendations were originally developed for NGA-East, they and the methodology they are based on can be adapted to become portable to other GMM and engineering problems requiring the computation of PSA from FAS.

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A research on fiber-optic vibration pattern recognition based on time-frequency characteristics

Advances in Mechanical Engineering ◽

10.1177/1687814018813468 ◽

2018 ◽

Vol 10 (12) ◽

pp. 168781401881346 ◽

Cited By ~ 3

Author(s):

Tabi Fouda Bernard Marie ◽

Dezhi Han ◽

Bowen An ◽

Jingyun Li

Keyword(s):

Pattern Recognition ◽

Frequency Domain ◽

Time Domain ◽

Fiber Optic ◽

Pattern Recognition Method ◽

Recognition Method ◽

Time Frequency ◽

Mode Decomposition ◽

Vibration Pattern ◽

The Time Domain

To detect and recognize any type of events over the perimeter security system, this article proposes a fiber-optic vibration pattern recognition method based on the combination of time-domain features and time-frequency domain features. The performance parameters (event recognition, event location, and event classification) are very important and describe the validity of this article. The pattern recognition method is precisely based on the empirical mode decomposition of time-frequency entropy and center-of-gravity frequency. It implements the function of identifying and classifying the event (intrusions or non-intrusion) over the perimeter to secure. To achieve this method, the first-level prejudgment is performed according to the time-domain features of the vibration signal, and the second-level prediction is carried out through time-frequency analysis. The time-frequency distribution of the signal is obtained by empirical mode decomposition and Hilbert transform and then the time-frequency entropy and center-of-gravity frequency are used to form the time-frequency domain features, that is, combined with the time-domain features to form feature vectors. Multiple types of probabilistic neural networks are identified to determine whether there are intrusions and the intrusion types. The experimental results demonstrate that the proposed method is effective and reliable in identifying and classifying the type of event.

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Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

Mathematical Problems in Engineering ◽

10.1155/2018/7982342 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11

Author(s):

Chen Xia ◽

Chengzhi Qi ◽

Xiaozhao Li

Keyword(s):

Finite Element ◽

Seismic Response ◽

Time Domain ◽

Seismic Waves ◽

Three Dimensional ◽

Seismic Loads ◽

Element Analysis ◽

Artificial Boundaries ◽

The Time Domain ◽

Transmitting Boundaries

Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil.

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Seismic response and retrofit of industrial brick masonry chimneys

Canadian Journal of Civil Engineering ◽

10.1139/l92-012 ◽

1992 ◽

Vol 19 (1) ◽

pp. 117-128 ◽

Cited By ~ 14

Author(s):

A. Ghobarah ◽

T. Baumber

Keyword(s):

Seismic Response ◽

Ground Motion ◽

Strong Motion ◽

Brick Masonry ◽

Wind Loading ◽

Earthquake Ground Motion ◽

Lumped Mass ◽

Mass System ◽

Higher Modes ◽

Recent Earthquakes

During recent earthquakes, the documented cases of collapsed unreinforced brick masonry industrial chimneys are numerous. Observed modes of structural failure are either total collapse or sometimes collapse or damage of the top third of the structure. The objective of this study is to analyze and explain the modes of observed failure of masonry chimneys during earthquake events, and to evaluate two retrofit systems for existing chimneys in areas of high seismicity. The behaviour of the masonry chimney, when subjected to earthquake ground motion, was modelled using a lumped mass system. Several actual strong motion records were used as input to the model. The shear, moment, and displacement responses to the earthquake ground motion were evaluated for various chimney configurations. It was found that the failure of the chimney at its base is the result of the fundamental mode of vibration. Failure at the top third of the structure due to the higher modes of vibration is possible when the chimney is subjected to high frequency content earthquakes. Higher modes, which are normally not of concern under wind loading, were shown to be critical in seismic design. Post-tensioning and the reinforcing steel cage were found to be effective retrofit systems. Key words: masonry, chimneys, behaviour, analysis, design, retrofit, dynamic, earthquakes, seismic response.

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Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations

Bulletin of the Seismological Society of America ◽

10.1785/0120210101 ◽

2021 ◽

Author(s):

Alan Poulos ◽

Eduardo Miranda ◽

Jack W. Baker

Keyword(s):

Stochastic Process ◽

Ground Motion ◽

Ground Motions ◽

Gaussian White Noise ◽

Response Spectra ◽

Orientation Dependence ◽

Stochastic Simulations ◽

Earthquake Ground Motion ◽

Significant Duration ◽

Simulated Ground Motions

ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.

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Vibrations in CDFW

Entropy ◽

10.3390/e22060704 ◽

2020 ◽

Vol 22 (6) ◽

pp. 704

Author(s):

Daniel Soares de Alcantara ◽

Pedro Paulo Balestrassi ◽

José Henrique Freitas Gomes ◽

Carlos Alberto Carvalho Castro

Keyword(s):

Time Domain ◽

Low Frequency ◽

Welding Process ◽

Statistical Characteristics ◽

Crest Factor ◽

Vibration Signals ◽

Mode Decomposition ◽

Complex Process ◽

The Time Domain ◽

Peak Value

Continuous drive friction welding is a solid-state welding process that has been experimentally proven to be a fast and reliable method. This is a complex process; deformations in the viscosity of a material alter the friction between the surfaces of the pieces. All these dynamics cause changes in the vibration signals; the interpretation of these signals can reveal important information. The vibration signals generated during the friction and forging stages are measured on the stationary part of the structure to determine the influence of the manipulated variables on the time domain statistical characteristics (root mean square, peak value, crest factor, and kurtosis). In the frequency domain, empirical mode decomposition is used to characterize frequencies. It was observed that it is possible to identify the effects of the manipulated variables on the calculated statistical characteristics. The results also indicate that the effect of manipulated variables is stronger on low-frequency signals.

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