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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 15:02:38 +0000Studies of response to earthquake ground motion
https://resolver.caltech.edu/CaltechEERL:1966.EERL.1966.001
Authors: {'items': [{'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'Arthur Gerald'}}]}
Year: 1966
A study is made of the accuracy of electronic digital computer calculations of ground displacement and response spectra from strong-motion earthquake accelerograms. This involves an investigation of methods of the preparatory reduction of accelerograms into a form useful for the digital computations and of the accuracy of subsequent digital calculations. Various checks are made for both the ground displacement and response spectra results, and it is concluded that the main errors are those involved in digitizing the original record. Differences resulting from various investigators digitizing the same experimental record may become as large as 100% of the maximum computed ground displacements. The spread of the results of ground displacement calculations is greater than that of the response spectra calculations. Standardized methods of adjustment and calculation are recommended, to minimize such errors.
Studies are made of the spread of response spectral values about their mean. The distribution is investigated experimentally by Monte Carlo techniques using an electric analog system with white noise excitation, and histograms are presented indicating the dependence of the distribution on the damping and period of the structure. Approximate distributions are obtained analytically by confirming and extending existing results with accurate digital computer calculations. A comparison of the experimental and analytical approaches indicates good agreement for low damping values where the approximations are valid. A family of distribution curves to be used in conjunction with existing average spectra is presented. The combination of analog and digital computations used with Monte Carlo techniques is a promising approach to the statistical problems of earthquake engineering.
Methods of analysis of very small earthquake ground motion records obtained simultaneously at different sites are discussed. The advantages of Fourier spectrum analysis for certain types of studies and methods of calculation of Fourier spectra are presented. The digitizing and analysis of several earthquake records is described and checks are made of the dependence of results on digitizing procedure, earthquake duration and integration step length. Possible dangers of a direct ratio comparison of Fourier spectra curves are pointed out and the necessity for some type of smoothing procedure before comparison is established. A standard method of analysis for the study of comparative ground motion at different sites is recommended.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/m7q42-cmy68High frequency errors and instrument corrections of strong-motion accelerograms
https://resolver.caltech.edu/CaltechEERL:1971.EERL-71-05
Authors: {'items': [{'id': 'Trifunac-M-D', 'name': {'family': 'Trifunac', 'given': 'Mihailo D.'}}, {'id': 'Udwadia-F-E', 'name': {'family': 'Udwadia', 'given': 'F. E.'}}, {'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'Arthur Gerald'}}]}
Year: 1971
A study of high-frequency errors present in digitized accelerograms and an analysis of the distribution of unequally spaced, hand-digitized data indicates that the Fourier content of digitized accelerogram. data may be accurate up to about 25 cps.
Two methods for accelerometer instrument correction are described: (1) a direct numerical differentiation of recorded accelerograms from which high-frequency digitization errors have been filtered out and (2) an ideal "mathematical accelerometer" with a natural frequency significantly higher than the natural frequency of the recording instrument. Although both methods give good results, the first one is recommended for the standard use.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/b4sdc-mah64On the correlation of seismic intensity scales with the peaks of recorded strong ground motion
https://resolver.caltech.edu/CaltechAUTHORS:20140812-123942383
Authors: {'items': [{'id': 'Trifunac-M-D', 'name': {'family': 'Trifunac', 'given': 'M. D.'}}, {'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'A. G.'}}]}
Year: 1975
Correlations of the recorded peak acceleration, velocity and displacement, and the Modified Mercalli intensity have been carried out for 57 earthquakes and 187 strong-motion accelerograms recorded in the Western United States. Correlations of peak acceleration with intensity, characterized by the data scatter exceeding one order of magnitude, have lead to average peak accelerations which are higher than those reported by a majority of previous investigators. New correlations, also characterized by scatter of data of about one order of magnitude, have been presented for peak velocities and displacements of strong ground motion versus Modified Mercalli intensity.
Grouping of all recorded data according to the geology underlying the strong-motion accelerograph stations was carried out and permitted a study of the possible effects that local geology might have on the peaks of strong-motion acceleration, velocity, and displacement. Results of this analysis are as follows: (1) For ground shaking of a particular Modified Mercalli intensity, average peak acceleration recorded on hard rock is higher by a factor less than about two than the average peak acceleration recorded on alluvium; (2) the effect of local geology on the average peak velocity leads to marginally higher peak values on alluvium; and (3) the peak ground displacements are larger, by a factor less than two, when recorded on alluvium rather than on hard rock.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/79k73-43a77On correlation of seismoscope response with earthquake magnitude and Modified Mercalli Intensity
https://resolver.caltech.edu/CaltechAUTHORS:20140812-134447414
Authors: {'items': [{'id': 'Trifunac-M-D', 'name': {'family': 'Trifunac', 'given': 'M. D.'}}, {'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'A. G.'}}]}
Year: 1975
A quantitative measure of the Modified Mercalli Intensity Scale for earthquakes in the western United States has been developed by correlating the peak seismoscope relative displacement response, S_d, with the reported site intensity, I_(MM). This correlation can be approximated by
S̄_d(cm) ≈ 1/49.2(10^(0.288 I_MM))
for I_(MM) ≦ VIII and is characterized by one standard deviation of about 0.7 S̄_d. The data used in this study do not indicate an obvious type of dependence of S_d on local site conditions.
A method for computing the analog of the local earthquake magnitude, M_(seismoscope), has been presented for possible use in strong-motion seismology and for scaling earthquakes by close-in measurements, when other seismological instruments may go off scale.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zz6nt-b8g08A study on the duration of strong earthquake ground motion
https://resolver.caltech.edu/CaltechAUTHORS:20140812-160444836
Authors: {'items': [{'id': 'Trifunac-M-D', 'name': {'family': 'Trifunac', 'given': 'M. D.'}}, {'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'A. G.'}}]}
Year: 1975
A simple definition of the duration of strong earthquake ground motion based on the mean-square integral of motion has been presented. It is closely related to that part of the strong motion which contributes significantly to the seismic energy as recorded at a point and to the related spectral amplitudes. Correlations have been established between the duration of strong-motion acceleration, velocity, and displacement and Modified Mercalli intensity, earthquake magnitude, the type of recording site geology, and epicentral distance. Simple relations have been presented that predict the average trend of the duration and other related parameters as a function of Modified Mercalli intensity, earthquake magnitude, site geology and epicentral distance.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jadpx-amb93The 1987 Whittier Narrows Earthquake in the Los Angeles Metropolitan Area, California
https://resolver.caltech.edu/CaltechAUTHORS:20130220-090842835
Authors: {'items': [{'id': 'Hauksson-E', 'name': {'family': 'Hauksson', 'given': 'Egill'}, 'orcid': '0000-0002-6834-5051'}, {'id': 'Jones-L-M', 'name': {'family': 'Jones', 'given': 'Lucile M.'}, 'orcid': '0000-0002-2690-3051'}, {'id': 'Davis-T-L', 'name': {'family': 'Davis', 'given': 'Thomas L.'}}, {'id': 'Hutton-K', 'name': {'family': 'Hutton', 'given': 'L. Katherine'}}, {'id': 'Brady-A-G', 'name': {'family': 'Brady', 'given': 'A. Gerald'}}, {'id': 'Reasenberg-P-A', 'name': {'family': 'Reasenberg', 'given': 'Paul A.'}}, {'id': 'Michael-A-J', 'name': {'family': 'Michael', 'given': 'Andrew J.'}}, {'id': 'Yerkes-R-F', 'name': {'family': 'Yerkes', 'given': 'Robert F.'}}, {'id': 'Williams-P', 'name': {'family': 'Williams', 'given': 'Patrick'}}, {'id': 'Reagor-G', 'name': {'family': 'Reagor', 'given': 'Glen'}}, {'id': 'Stover-C-W', 'name': {'family': 'Stover', 'given': 'Carl W.'}}, {'id': 'Bent-A-L', 'name': {'family': 'Bent', 'given': 'Allison L.'}}, {'id': 'Shakal-A-K', 'name': {'family': 'Shakal', 'given': 'Anthony K.'}}, {'id': 'Etheredge-E', 'name': {'family': 'Etheredge', 'given': 'Edwin'}}, {'id': 'Porcella-R-L', 'name': {'family': 'Porcella', 'given': 'Ronald L.'}}, {'id': 'Bufe-C-G', 'name': {'family': 'Bufe', 'given': 'Charles G.'}}, {'id': 'Johnston-M-J-S', 'name': {'family': 'Johnston', 'given': 'Malcolm J. S.'}}, {'id': 'Cranswick-E', 'name': {'family': 'Cranswick', 'given': 'Edward'}}]}
Year: 1988
DOI: 10.1126/science.239.4846.1409
The Whittier Narrows earthquake sequence (local magnitude, M_L = 5.9), which
caused over $358-million damage, indicates that assessments of earthquake hazards in
the Los Angeles metropolitan area may be underestimated. The sequence ruptured a
previously unidentified thrust fault that may be part of a large system of thrust faults
that extends across the entire east-west length of the northern margin of the Los
Angeles basin. Peak horizontal accelerations from the main shock, which were
measured at ground level and in structures, were as high as 0.6g (where g is the
acceleration of gravity at sea level) within 50 kilometers of the epicenter. The
distribution of the modified Mercalli intensity VII reflects a broad north-south
elongated zone of damage that is approximately centered on the main shock epicenter.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kstpx-sda68