scholarly journals Distant motions from a building vibration test

1970 ◽  
Vol 60 (6) ◽  
pp. 2037-2043 ◽  
Author(s):  
Paul C. Jennings
Keyword(s):  
Ground Motion ◽  
Vertical Component ◽  
Excitation Level ◽  
Vibration Test ◽  
Multistory Buildings ◽  
Dynamic Forces ◽  
Horizontal Ground Motion ◽  
Vibration Tests

Abstract Horizontal ground motion generated by vibration tests of the nine-story Millikan Library Building on the Caltech campus was recorded on the surface of the ground in the Pasadena area at distances up to 3 miles from the building. Later it was learned that the vertical component of the motion also was recorded by the seismograph on Mt. Wilson, 6.7 miles from the Library and 4,800 ft higher in elevation. The magnitude of the acceleration varied from 2.04 × 10-2g at the excitation level on the ninth floor of the building to 3.2 × 10-7g at Mt. Wilson. Simple calculations show that multistory buildings are particularly well-suited for inducing large dynamic forces in the ground with relatively small equipment.

The High-Frequency Decay Slope of Spectra (Kappa) for M≥3.5 Earthquakes on Rock Sites in Eastern and Western Canada

2020 ◽  
Vol 110 (2) ◽  
pp. 471-488 ◽  
Author(s):  
Samantha M. Palmer ◽  
Gail M. Atkinson
Keyword(s):  
Ground Motion ◽  
Classical Method ◽  
Vertical Component ◽  
Western Canada ◽  
S Wave ◽  
Motion Modeling ◽  
Eastern Canada ◽  
General Observation ◽  
Anelastic Attenuation ◽  
Two Parameters

ABSTRACT Spectral decay of ground-motion amplitudes at high frequencies is primarily influenced by two parameters: site-related kappa (κ0) and regional Q (quality factor, inversely proportional to anelastic attenuation). We examine kappa and apparent Q-values (Qa) for M≥3.5 earthquakes recorded at seismograph stations on rock sites in eastern and western Canada. Our database contains 20 earthquakes recorded on nine stations in eastern Canada and 404 earthquakes recorded on eight stations in western Canada, resulting in 105 and 865 Fourier amplitude spectra, respectively. We apply two different methods: (1) a modified version of the classical S-wave acceleration method; and (2) a new stacking method that is consistent with the use of kappa in ground-motion modeling. The results are robust with respect to the method used and also with respect to the frequency band selected, which ranges from 9 to 38 Hz depending on the region, event, and method. Kappa values obtained from the classical method are consistent with those of the stacked method, but the stacked method provides a lower uncertainty. A general observation is that kappa is usually larger, and apparent Q is smaller, for the horizontal component in comparison to the vertical component. We determine an average regional κ0=7  ms (horizontal) and 0 ms (vertical) for rock sites in eastern Canada; we obtain κ0=19  ms (horizontal) and 14 ms (vertical) for rock sites in western Canada. We note that kappa measurements are quite sensitive to details of data selection criteria and methodology, and may be significantly influenced by site effects, resulting in large site-to-site variability.

Are Near-Fault Fling Effects Captured in the New NGA West2 Ground Motion Models?

2015 ◽  
Vol 31 (3) ◽  
pp. 1629-1645 ◽  
Author(s):  
Ronnie Kamai ◽  
Norman Abrahamson
Keyword(s):  
Ground Motion ◽  
Vertical Component ◽  
Strong Motion ◽  
Motion Processing ◽  
Large Set ◽  
Pass Filter ◽  
Motion Models ◽  
Finite Fault ◽  
Maximum Period ◽  
Ground Motion Models

We evaluate how much of the fling effect is removed from the NGA database and accompanying GMPEs due to standard strong motion processing. The analysis uses a large set of finite-fault simulations, processed with four different high-pass filter corners, representing the distribution within the PEER ground motion database. The effects of processing on the average horizontal component, the vertical component, and peak ground motion values are evaluated by taking the ratio between unprocessed and processed values. The results show that PGA, PGV, and other spectral values are not significantly affected by processing, partly thanks to the maximum period constraint used when developing the NGA GMPEs, but that the bias in peak ground displacement should not be ignored.

Evaluation of Seismic Performance of Moment Resisting Frames considering Vertical Component of Ground Motion

2012 ◽  
Vol 15 (8) ◽  
pp. 1439-1453 ◽  
Author(s):  
Behrouz Asgarian ◽  
Anahita Norouzi ◽  
Pejman Alanjari ◽  
Masoud Mirtaheri
Keyword(s):  
Ground Motion ◽  
Seismic Performance ◽  
Vertical Component ◽  
Moment Resisting Frames ◽  
Moment Resisting

Dynamics of Rigid Block due to Horizontal Ground Motion

1998 ◽  
Vol 124 (7) ◽  
pp. 713-717 ◽  
Author(s):  
A. Pompei ◽  
A. Scalia ◽  
M. A. Sumbatyan
Keyword(s):  
Ground Motion ◽  
Rigid Block ◽  
Horizontal Ground Motion

Coupled torsional dynamic analysis of a multistory building

1973 ◽  
Vol 63 (3) ◽  
pp. 1025-1039
Author(s):  
Bruce M. Douglas ◽  
Thomas E. Trabert
Keyword(s):  
Ground Motion ◽  
Degrees Of Freedom ◽  
Seismic Waves ◽  
Structural Response ◽  
Tall Buildings ◽  
Strong Motion ◽  
Ambient Vibration ◽  
Simultaneous Application ◽  
Vibration Data ◽  
Horizontal Ground Motion

abstract The coupled bending and torsional vibrations of a relatively symmetric 22-story reinforced concrete building in Reno, Nevada are studied. Analytical results are compared with observations obtained during the nuclear explosion FAULTLESS and to ambient vibration data. The fundamental periods of vibration observed during FAULTLESS were (TNS = 1.42, TEW = 1.81, TTORSION = 1.12 sec), and the calculated periods were (TNS = 2.14, TEW = 2.07, TTORSION = 1.90 sec). It was estimated that between 25 and 45 per cent of the total available nonstructural stiffness was required to explain the differences in the observed and calculated fundamental periods. Each floor diaphragm in the system was allowed three degrees of freedom-two translations and a rotation. It was found that coupled torsional motions can influence the response of structural elements near the periphery of the structure. Strong-motion structural response calculations comparing the simultaneous use of both components of horizontal ground motion to a single component analysis showed that the simultaneous application of both components of ground motion can significantly alter the response of lateral load-carrying elements. Differences of the order of 45 per cent were observed in the frames near the ends of the structure. Also, it was shown that the overall response of tall buildings is sensitive not only to the choice of input ground motion but also to the orientation of the structure with respect to the seismic waves.

scholarly journals Numerical assessment of vertical ground motion effects on highway bridges

2020 ◽  
Vol 47 (7) ◽  
pp. 790-800 ◽  
Author(s):  
Hadi Aryan ◽  
Mehdi Ghassemieh
Keyword(s):  
Ground Motion ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vertical Component ◽  
Time History ◽  
Highway Bridges ◽  
Vertical Excitation ◽  
Vertical Ground Motion ◽  
Field Evidence ◽  
Vertical Ground

Field evidence of recent earthquakes shows serious bridge damages due to the direct compression or tension in the columns and some flexural and shear failures caused by the variation in axial force of the columns. These damages could not be produced solely by the horizontal seismic excitations; the vertical component of the earthquake is involved. This paper presents a numerical study highlighting the presence of vertical seismic excitation. Nonlinear time history analyses are conducted on detailed three-dimensional models of multi-span simply supported and multi-span continuous bridges using a suite of representative ground motions. The results showed the significant influence of vertical excitation on the bridge responses. Therefore, it is imperative to include more efficient criteria to upgrade the design codes and extend practical techniques that consider and cope with the structural effects of vertical ground motion along with the horizontal excitations.

Response spectral matching of horizontal ground motion components to an orientation-independent spectrum (RotDnn)

2020 ◽  
pp. 875529302097098
Author(s):  
Luis A Montejo
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Response Spectra ◽  
Major Axis ◽  
Component Level ◽  
Nonlinear Characteristics ◽  
Target Spectrum ◽  
Horizontal Ground Motion ◽  
Median Spectrum

This article presents a methodology to spectrally match two horizontal ground motion components to an orientation-independent target spectrum (RotDnn). The algorithm is based on the continuous wavelet transform decomposition and iterative manipulation of the two horizontal components of a seed record. The numerical examples presented follow current ASCE/SEI 7 specifications and therefore maximum-direction spectra (RotD100) are used as target for the match. However, the proposed methodology can be used to match other RotDnn spectra, like the median spectrum (RotD50). It is shown that with the proposed methodology the resulting RotDnn from the modified horizontal components closely match the smooth target RotDnn spectrum, while the response spectrum for each horizontal component continue to exhibit a realistic jagged behavior. The response spectra variability at the component level within suites of spectrally matched motions was found to be of the same order than the variability measured in suites composed of amplitude scaled records. Moreover, the spectrally matched records generated preserved most of the characteristics of the seed records, including the nonlinear characteristics of the time history traces and the period-dependent major axis orientations.

scholarly journals Scaling of Vertical Component of Seismic Ground Motion

2020 ◽  
Vol 59 (5) ◽  
pp. 3827-3845
Author(s):  
Fikrat ALMahdi ◽  
Yasin Fahjan ◽  
Adem Dogˇangün
Keyword(s):  
Ground Motion ◽  
Vertical Component ◽  
Seismic Ground Motion

Magnetic Field Variations in Alaska: Recording Space Weather Events on Seismic Stations in Alaska

2020 ◽  
Vol 110 (5) ◽  
pp. 2530-2540 ◽  
Author(s):  
Adam T. Ringler ◽  
Robert E. Anthony ◽  
David C. Wilson ◽  
Abram C. Claycomb ◽  
John Spritzer
Keyword(s):  
Magnetic Field ◽  
Ground Motion ◽  
Space Weather ◽  
Vertical Component ◽  
Environmental Data ◽  
Magnetic Data ◽  
Seismic Stations ◽  
Weather Events ◽  
S Period ◽  
Magnetic Field Variations

ABSTRACT Seismometers are highly sensitive instruments to not only ground motion but also many other nonseismic noise sources (e.g., temperature, pressure, and magnetic field variations). We show that the Alaska component of the Transportable Array is particularly susceptible to recording magnetic storms and other space weather events because the sensors used in this network are unshielded and magnetic flux variations are stronger at higher latitudes. We also show that vertical-component seismic records across Alaska are directly recording magnetic field variations between 40 and 800 s period as opposed to actual ground motion during geomagnetic events with sensitivities ranging from 0.004 to 0.48  (m/s2)/T. These sensitivities were found on a day where the root mean square variation in the magnetic field was 225 nT. Using a method developed by Forbriger (2007, his section 3.1), we show that improving vertical seismic resolution of an unshielded sensor by as much as 10 dB in the 100–400 s period band using magnetic data from a collocated three-component magnetometer is possible. However, due to large spatial variations in Earth’s magnetic field, this methodology becomes increasingly ineffective as the distance between the seismometer and magnetometer increases (no more than 200 km separation). A potential solution to this issue may be to incorporate relatively low-cost magnetometers as an additional environmental data stream at high-latitude seismic stations. We demonstrate that the Bartington Mag-690 sensors currently deployed at Global Seismographic Network sites are not only acceptable for performing corrections to seismic data, but are also capable of recording many magnetic field signals with similar signal-to-noise ratios, in the 20–1000 s period band, as the observatory grade magnetometers operated by the U.S. Geological Survey Geomagnetism Program. This approach would densify magnetic field observations and could also contribute to space weather monitoring by supplementing highly calibrated magnetometers with additional sensors.

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