scholarly journals Bizarre Waveforms in Strong Motion Records

2015 ◽  
Vol 2015 ◽  
pp. 1-17
Author(s):  
Baofeng Zhou ◽  
Haiyun Wang ◽  
Lili Xie ◽  
Yanru Wang
Keyword(s):  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Time History ◽  
Strong Motion ◽  
Ratio Method ◽  
Asymmetric Waveform ◽  
Baseline Drift ◽  
Strong Motion Records ◽  
Before And After ◽  
Fourier Amplitude Spectrum

This paper collects a rich set of strong motion records in some typical earthquakes domestic and abroad, checks its seismic events, converts the data format, corrects the zeroline and draws the waveform. Four kinds of abnormal phenomena on the acceleration waveform are revealed, such as spike, asymmetric waveform, obvious baseline drift, and strong motion records packets separation. Then reasonable processing approaches are derived from the preliminary analysis of the generation mechanism for abnormal phenomena. In addition to the effects on time history, Fourier amplitude spectrum and response spectrum are studied before and after strong motion records correction. It is shown that (1) mechanism of spikes is rather complicated; however spikes can be eliminated by “jerk” method, ratio method, and the consistency of the three-component PGA time; (2) mechanism of the asymmetric waveform is of diversity; however, to some extent, the Butterworth low-pass filtering can be applied to correct it; (3) two pieces of strong motion record packets can be connected by searching continuous and repeated data; (4) the method of cumulative adding can be used to find the clear baseline drift; (5) the abnormal waveform directly affects the characteristics of time history and frequency spectrum.

Near-Fault Baseline Correction Method and Appliction in Wenchuan Earthquake

2012 ◽  
Vol 166-169 ◽  
pp. 2517-2521
Author(s):  
Xiao Bo Peng ◽  
Xiao Jun Peng ◽  
Wei Lin Yang
Keyword(s):  
Wenchuan Earthquake ◽  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Time History ◽  
Relative Displacement ◽  
Correction Method ◽  
Baseline Correction ◽  
Fourier Amplitude ◽  
Surface Rupture ◽  
Fourier Amplitude Spectrum

To eliminate the drifting in recordings from Ms8.0 Wenchuan earthquake, a modified two segments baseline correction method is brought up and systematic acceptance standard is presented. The method is applied to recordings from Qingping station and Bajiao station, which are closest stations to surface rupture traces. The effect of baseline correction on acceleration time history, Fourier amplitude spectrum and 5% damped relative displacement response spectrum is analyzed.

Use of RVT for Computation of In-Structure Response Spectra and Peak Responses and Comparison to Time History and Response Spectrum Analysis

2018 ◽  
Vol 34 (4) ◽  
pp. 1913-1930 ◽  
Author(s):  
Irmela Zentner
Keyword(s):  
Response Spectrum ◽  
Structural Response ◽  
Time History ◽  
Strong Motion ◽  
Response Spectra ◽  
Combination Rules ◽  
Floor Response Spectra ◽  
Power Spectral ◽  
Time Histories ◽  
Definition Of

The random vibration theory offers a framework for the conversion of response spectra into power spectral densities (PSDs) and vice versa. The PSD is a mathematically more suitable quantity for structural dynamics analysis and can be straightforwardly used to compute structural response in the frequency domain. This allows for the computation of in-structure floor response spectra and peak responses by conducting only one structural analysis. In particular, there is no need to select or generate spectrum-compatible time histories to conduct the analysis. Peak response quantities and confidence intervals can be computed without any further simplifications such as currently used in the response spectrum method, where modal combination rules have to be derived. In contrast to many former studies, the Arias intensity-based definition of strong-motion duration is adopted here. This paper shows that, if the same definitions of strong-motion duration and modeling assumptions are used for time history and RVT computations, then the same result can be expected. This is illustrated by application to a simplified model of a reactor building.

Site response analysis of liquefiable soil employing continuous wavelet transform

2022 ◽  
Vol 12 (1) ◽  
pp. 1-33
Author(s):  
D. Chavan ◽  
T.G. Sitharam ◽  
P. Anbazhagan
Keyword(s):  
Wavelet Transform ◽  
Site Response ◽  
Amplitude Spectrum ◽  
Ground Surface ◽  
Time History ◽  
Response Analysis ◽  
Fourier Amplitude ◽  
Acceleration Time ◽  
Liquefiable Soil ◽  
Fourier Amplitude Spectrum

Propagation of the earthquake motion towards the ground surface alters both the acceleration and frequency content of the motion. Acceleration time record and Fourier amplitude spectrum of the motion reveal changes in the acceleration and frequency content. However, Fourier amplitude spectrum fails to give frequency-time variation. Wavelet transform overcomes this difficulty. In the present study, site response analysis of a liquefiable soil domain has been investigated employing wavelet transform. Three earthquake motions with distinct predominant frequencies are considered. It is revealed that the moment soil undergoes initial liquefaction, it causes a spike in the acceleration time history. Frequency of the spikes is found to be greater than the predominant frequency of the acceleration-time history recorded at the ground surface from the analysis. Interestingly, the spikes belong to the sharp tips of the shear stress-shear strain curve. Immediately after the spike, acceleration deamplification is observed. Post-liquefaction deamplification (filtering) of the frequency components is also observed.

Strong-Motion Records for Site-Specific Analysis

2003 ◽  
Vol 19 (3) ◽  
pp. 557-578 ◽  
Author(s):  
Praveen K. Malhotra
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Response Spectrum ◽  
Strong Motion ◽  
Response Spectra ◽  
Seismic Events ◽  
Site Specific ◽  
Strong Motion Records ◽  
Specific Analysis ◽  
Selection Of

A procedure is presented to select and scale strong-motion records for site-specific analysis. The procedure matches records’ smooth response spectra with the site response spectrum by scaling of the acceleration histories. The parameters defining the smooth spectrum of various records are computed and tabulated to allow easy selection of records. Hazard de-aggregation is used to identify closer and distant seismic events, which are simulated by the scaled ground motion histories. The procedure can also be used to obtain ground motion pairs in orthogonal directions for multidimensional dynamic response analyses.

The Research of Input Ground Motion on Seismic Fragility Analysis of Bridges

2012 ◽  
Vol 490-495 ◽  
pp. 1826-1830
Author(s):  
Yun Zhang ◽  
Pin Tan ◽  
Xiao Rong Zhou
Keyword(s):  
Ground Motion ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Design Response Spectrum ◽  
Methods Of Synthesis ◽  
Fourier Amplitude Spectrum

Analyzed the importance of selecting reasonably ground motion input in seismic fragility analysis of the bridge. Based on the common methods of synthesis artificial seismic wave which used trigonometric series and according to the characters of Fourier series, extracted phase spectrum from practical seismic waves ,through modulating the Fourier amplitude spectrum, obtained the artificial seismic wave which fitted compatible with the design response spectrum. Similar to nature small earthquake records, it has the character of non-stationary on time-domain and frequency-domain. Synthesize a series of artificial seismic waves in this method, can improve the accuracy and pertinence of the bridge seismic fragility.

Method for Generating Design Earthquake Time Histories With an Emphasis on Maintaining Phasing

2010 ◽  
Author(s):  
R. E. Spears
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Strong Motion ◽  
Low Energy ◽  
Design Response Spectrum ◽  
Multistep Process ◽  
Time Histories ◽  
Design Earthquake ◽  
Original Time

A method has been developed which takes a seed earthquake time history and modifies it to produce a time-history with a given design response spectrum. It is a multistep process with an emphasis on maintaining phasing during the strong motion duration. Initially, the seed earthquake time history is broken into a series of separate time histories which added together produce the original time history. Each separate time history is drift corrected using modifications only outside the strong motion duration of the seed earthquake time history. This allows the separate time histories to be individually scaled to improve the response spectrum match while the phase of the motion during the strong motion duration remains unchanged. To further improve the design response spectrum match, low cycle, low energy waves are added. This is primarily to control the response at higher frequency. These waves are tuned to improve the response at existing peaks.

An Empirical Relationship between Fourier and Response Spectra Using Spectrum-Compatible Times Series

2017 ◽  
Vol 33 (1) ◽  
pp. 179-199 ◽  
Author(s):  
Luis A. Montejo ◽  
Aidcer L. Vidot-Vega
Keyword(s):  
Time Series ◽  
Earthquake Engineering ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Dependence ◽  
Empirical Relationship ◽  
Amplitude Spectrum ◽  
Strong Motion ◽  
Response Spectra ◽  
Elastic Response

The Fourier amplitude spectrum (FAS) is widely used in seismology and earthquake engineering as it provides valuable information regarding frequency dependent amplitude of the ground motion. However, for structural design and assessment, the preferred representation of seismic hazard continues to be based on the elastic response spectrum. Therefore, conversions between these spectra are often required. In this article, the connection between FAS and the 5% damping pseudo-acceleration response spectrum (5% PSA) is explored using large data sets of spectrum-compatible time series generated from white noise. The strong dependence of the relation between FAS and 5% PSA with strong motion duration is evidenced and a duration dependent empirical relationship between the both spectra is developed. The equation is validated using recorded ground motions and spectrum-compatible time series generated from the modification of these ground motions. The equation allows simpler one-step conversions when compared to iterative approaches based on RVT theory or time-consuming methodologies that require the generation of spectrum-compatible time series.

scholarly journals Detecting Site Resonant Frequency Using HVSR: Fourier versus Response Spectrum and the First versus the Highest Peak Frequency

2020 ◽  
Vol 110 (2) ◽  
pp. 427-440 ◽  
Author(s):  
Chuanbin Zhu ◽  
Fabrice Cotton ◽  
Marco Pilz
Keyword(s):  
Site Response ◽  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Spectral Ratio ◽  
Peak Frequency ◽  
Fourier Amplitude ◽  
Resonant Frequencies ◽  
Overall Performance ◽  
Fourier Amplitude Spectrum ◽  
Hvsr Technique

ABSTRACT In this investigation, we examine the uncertainties using the horizontal-to-vertical spectral ratio (HVSR) technique on earthquake recordings to detect site resonant frequencies at 207 KiK-net sites. Our results show that the scenario dependence of response (pseudospectral acceleration) spectral ratio could bias the estimates of resonant frequencies for sites having multiple significant peaks with comparable amplitudes. Thus, the Fourier amplitude spectrum (FAS) should be preferred in computing HVSR. For more than 80% of the investigated sites, the first peak (in the frequency domain) on the average HVSR curve over multiple sites coincides with the highest peak. However, for sites with multiple peaks, the highest peak frequency (fp) is less susceptible to the selection criteria of significant peaks and the extent of smoothing to spectrum than the first peak frequency (f0). Meanwhile, in comparison to the surface-to-borehole spectral ratio, f0 tends to underestimate the predominant frequency (at which the largest amplification occurs) more than fp. In addition, in terms of characterizing linear site response, fp shows a better overall performance than f0. Based on these findings, we thus recommend that seismic network operators provide fp on the average HVSRFAS curve as a priority, ideally together with the average HVSRFAS curve in site characterization.

FAS-Compatible Synthetic Signals for Equivalent-Linear Site Response Analyses

2018 ◽  
Vol 34 (1) ◽  
pp. 377-396 ◽  
Author(s):  
Margarita Chi-Miranda ◽  
Luis A. Montejo
Keyword(s):  
Site Response ◽  
Response Spectrum ◽  
Amplitude Spectrum ◽  
Extreme Value Statistics ◽  
Current Time ◽  
Equivalent Linear ◽  
Inelastic Demand ◽  
Design Response Spectrum ◽  
The Time Domain ◽  
Fourier Amplitude Spectrum

An alternative approach to generate the seismic input for equivalent-linear (EQL) site response analyses is proposed. The proposed approach encompasses the strengths from current time histories (THs) and random vibration theory (RVT) methods. It consists of the generation of synthetic signals in the time domain (analogous to the TH method) that are constructed to have a Fourier amplitude spectrum (FAS) compatible with the design response spectrum (analogous to the RVT method). Through this approach, the use of extreme value statistics (used in RVT and known to overestimate amplification functions) is avoided. Moreover, the need to develop an appropriate suite of realistic acceleration series, which is the most challenging and time-consuming part of the TH-based approach, is also circumvented. The methodology is evaluated through a comprehensive analysis that includes different site conditions, input spectral shapes, duration scenarios, levels of inelastic demand, and number of synthetic signals used.

THE STRONG MOTION RECORDS OF THE Ms 8.0 WENCHUAN EARTHQUAKE BY THE DIGITAL STRONG EARTHQUAKE NETWORK IN SICHUAN AND THE NEIGHBORING REGION

2011 ◽  
Vol 05 (04) ◽  
pp. 343-361 ◽  
Author(s):  
RONGJUN ZHOU ◽  
YONG LI ◽  
ALEXANDER L. DENSMORE ◽  
MIN LAI ◽  
YI ZHANG ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Response Spectrum ◽  
Hanging Wall ◽  
Strong Motion ◽  
Major Axis ◽  
Fracture Pattern ◽  
High Rate ◽  
Peak Acceleration ◽  
Ground Acceleration ◽  
Strong Motion Records

The M s 8.0 Wenchuan Earthquake of May 12, 2008 resulted in oblique dextral-thrust motion in the Longmen Shan tectonic belt resulted. During this earthquake event, 133 sets of three-component acceleration records were collected by the digital earthquake network in Sichuan Province. By using these records and some strong motion records from the networks in Shanxi and Gansu provinces, contours of peak ground acceleration were determined. These contours are elliptically shaped with the major axis oriented in a northeast direction. The peak acceleration decayed more gradually toward the northeast, parallel to the rupture propagation than toward the southwest, indicating a directivity effect. The peak acceleration also decayed more gradually toward the northwest, on the hanging wall, than toward the southeast on the footwall. A relatively high rate of attenuation in the peak acceleration was also evident on the Yingxiu-Beichuan section of the fault; this can be attributed to the seismic source fracture pattern and rupture progress. The measured peak vertical and horizontal ground acceleration components were far larger than the design values prescribed by the Code for Seismic Design of Buildings (GB50011-2001). As distance from the rupture increased, the acceleration response spectrum gradually became dominated by long-period motions. A large velocity pulse was also measured at a distance of about 80–100 km from the fault.

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