Download or read book Estimation of Non Linear Seismic Site Effects for Deep Deposits of the Mississippi Embayment written by Duhee Park and published by . This book was released on 2003 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Probabilistic Seismic Hazard Analysis of the Mississippi Embayment Incorporating Nonlinear Site Effects written by Mahesh Singh Dhar and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Mississippi Embayment (ME) area is prone to damaging earthquakes as it lies over the New Madrid Seismic Zone, which is considered the most seismically active zone in the central and eastern United States. Several attempts have been made to account for the influence of deep sediment deposits of the ME on the propagation of seismic waves. This study presents the seismic and liquefaction hazards of the ME by adding the local geologic conditions to the 2014 USGS National Seismic Hazard Model. Both equivalent linear and nonlinear site response codes have been used to determine the amplification distribution at a site. This study uses the most up-to-date information available from different researchers and attempts to reduce the effect of uncertainties. A new 3D geologic model has been generated to assign geologic information and shear wave velocity to the soil profiles distributed over the ME area. The 3D model helps to generate an interpolated soil profile at a site for more accurate site response analysis, replacing the use of generic soil profiles. For liquefaction hazard analysis, updated surface geologic maps and liquefaction potential curves have been used. At short periods corresponding to peak ground acceleration the results show that seismic hazard is reduced on the lowlands in comparison to USGS results, mainly due to deamplification of ground motions from strong nonlinearity in the softer soil deposits. The NOAH (nonlinear Iwan model) site response code shows slightly lower hazard on the lowland soils in comparison to those obtained from SHAKE91 (equivalent linear). At long periods, lowlands deposits amplify hazards more in comparison to corresponding USGS results, mainly due to much less soil nonlinearity at long periods. The liquefaction hazard tends to be high in Holocene and late Pleistocene lowlands sediments and low in Pleistocene loess of the uplands. The young sediments and shallow groundwater table depth in lowlands contribute to higher liquefaction hazard. Considering pore pressure effects in nonlinear site response analysis at a test site on the lowlands shows amplification of ground motion even at short periods. Therefore, pore pressure effects should be considered in seismic hazard analysis of the ME. .

Download or read book A Practical Course in Advanced Structural Design written by Tim Huff and published by CRC Press. This book was released on 2021-03-31 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Practical Course in Advanced Structural Design is written from the perspective of a practicing engineer, one with over 35 years of experience, now working in the academic world, who wishes to pass on lessons learned over the course of a structural engineering career. The book covers essential topics that will enable beginning structural engineers to gain an advanced understanding prior to entering the workforce, as well as topics which may receive little or no attention in a typical undergraduate curriculum. For example, many new structural engineers are faced with issues regarding estimating collapse loadings during earthquakes and establishing fatigue requirements for cyclic loading – but are typically not taught the underlying methodologies for a full understanding. Features: Advanced practice-oriented guidance on structural building and bridge design in a single volume. Detailed treatment of earthquake ground motion from multiple specifications (ASCE 7-16, ASCE 4-16, ASCE 43-05, AASHTO). Details of calculations for the advanced student as well as the practicing structural engineer. Practical example problems and numerous photographs from the author’s projects throughout. A Practical Course in Advanced Structural Design will serve as a useful text for graduate and upper-level undergraduate civil engineering students as well as practicing structural engineers.

Download or read book Ground Characterization and Foundations written by C. N. V. Satyanarayana Reddy and published by Springer Nature. This book was released on 2021-09-26 with total page 819 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises the select proceedings of the Indian Geotechnical Conference (IGC) 2020. The contents focus on recent developments in geotechnical engineering for a sustainable tomorrow. The book covers the topics related to traditional and latest methods in characterisation of ground at construction sites, recent technological developments/ advances in design of shallow and deep foundations in different subsoil conditions.

Download or read book Latest Developments in Geotechnical Earthquake Engineering and Soil Dynamics written by T.G. Sitharam and published by Springer Nature. This book was released on 2021-07-01 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume brings together contributions from world renowned researchers and practitioners in the field of geotechnical engineering. The chapters of this book are based on the keynote and invited lectures delivered at the 7th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. The book presents advances in the field of soil dynamics and geotechnical earthquake engineering. A strong emphasis is placed on proving connections between academic research and field practice, with many examples, case studies, best practices, and discussions on performance-based design. This volume will be of interest to research scholars, academicians and industry professionals alike.

Download or read book Site Effects Study in the Mississippi Embayment and Uncertainties Evaluation in Site Response Analysis written by Arash Yarahmadi and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The local site conditions have paramount influence on the characteristics of seismic ground shaking. There are several methods of investigating seismic site effects which can be classified into two major categories; common site-specific response analysis, and procedures that use solely earthquake time series like the Standard Spectral Ratio (SSR), and Horizontal to Vertical Ratio (HVSR) methods. In the SSR method, the spectral ratios of earthquake records at a certain station can be evaluated with respect to a reference station located on a nearby outcrop rock. In the first part of the dissertation, we use earthquake records to find reference stations and use that reference station to find the site amplifications at the target stations inside the Mississippi Embayment (ME). We found WHAR, W41B, and UALR seismic stations, which have reference stations characteristics, close to the ME using horizontal-to-vertical spectrum ratio (HVSR) method. Amplification factors are obtained for six target stations inside the ME using an inversion method with WHAR seismic station as the reference station. Thirty-five local and regional earthquakes in the New Madrid and Arkansas seismic zones are used to perform the inversion. The results show the fundamental frequencies of these stations are as low as 0.2 HZ to 1 HZ, which corresponds to the soft features of their local conditions. In the second part of this dissertation, we focus on finding uncertainties in the 1-D equivalent linear site response analysis (SRA). In SRA these uncertainties are accounted for by generating random cases of soil parameters. Choosing suitable randomization bounds can decrease the effects of the uncertainties in soil parameters on SRA results like predicted spectral accelerations. These bounds quantified by the coefficient of variation (COV), which can be defined for different soil parameters. Using Vertical seismometer arrays, we can compare predicted and observed surface ground motions. In this study we evaluate COVs for different parameters of the soil that are the main input parameters of equivalent linear SRA. Coefficients of variation which generate minimum root means square errors of the observed and predicted response spectra are obtained for different site classes..

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of the Horizontal to vertical Spectral Ratio HVSR Method for Characterization of Deep Soils in the Mississippi Embayment written by Ryan P. Goetz and published by . This book was released on 2009 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil deposits can significantly influence the amplitude and frequency content of surface ground motions during earthquakes. Estimating the fundamental frequency (f0) of a site is often needed for improved planning and design for future earthquakes. A cost-effective method of obtaining an estimate of f0 is the Horizontal-to-Vertical Spectral Ratio (HVSR) method (also termed Nakamura's method), which utilizes ambient energy recorded in the horizontal and vertical directions from a single, three-component sensor. In addition to estimating the fundamental frequency, average shear wave velocity (VS, AVG) values have been estimated using the HVSR method and a simple approximate relationship relating VS, AVG to f0 and the depth to bedrock. This procedure was performed by Bodin et al. (2001) to develop a relationship between VS, AVG and soil depths in the Mississippi embayment. However, this relationship predicts average velocity values that are about 25% higher than values predicted by another relationship developed using a different method (Chen et al. 1996). Although this inconsistency is known, the relationship of Bodin et al. (2001) is often cited as the best information on the velocity structure in the embayment. In addition, Bodin et al. (2001) identified a second frequency peak of unknown origin in their HVSR plots. The objectives of this study are to answer these unresolved questions, specifically: (1) why the shear wave velocity relationships developed for the Mississippi embayment using the HVSR method are inconsistent with other findings, and (2) the origin of the second frequency peak observed in HVSR plots from the Mississippi embayment. To meet these objectives, the following three studies were performed: (1) a parametric study of site factors influencing the fundamental frequency and average velocity estimates from the HVSR method, (2) an investigation into the influence of the HVSR processing parameters using experimental data collected at eleven deep soil sites in the Mississippi embayment, and (3) comparison of experimental and simulated HVSR results for Mississippi embayment sites. With regard to the first objective, it was found that the HVSR method yielded reliable values of the fundamental site frequency for conditions of high velocity contrast between soil and rock and saturated soil conditions (conditions that are met in the Mississippi embayment). Also, it was shown that varying the HVSR processing parameters had a negligible impact on the HVSR frequency estimates. However, it was demonstrated that use of the approximate method to estimate VS, AVG systematically over-predicted the true VS, AVG values. With regard to the second objective, it was shown that the second frequency peak observed in the experimental HVSR plots can be attributed to either a higher-mode resonance of horizontally-polarized shear waves reflecting from the soil/bedrock boundary or local site resonance due to a shallow contrast in VS within the soil deposit. Based on the findings of this study it is recommended that the VS relationship for the sediments of the Mississippi embayment developed by Chen et al. (1996) should be preferred to the Bodin et al. (2001) relationship.

Download or read book Seismic Site Response and Extraction of Dynamic Soil Behavior from Downhole Array Measurements written by Chi-Chin Tsai and published by ProQuest. This book was released on 2007 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic site response analysis is commonly used to predict ground responses due to local soil effects. This thesis consists of two main components (1) a new inverse analysis procedure to extract dynamic soil behavior from vertical arrays and (2) an enhanced assessment of site factors for the deep deposits of the Mississippi Embayment.

Download or read book Development of Shear Wave Velocity Profiles in the Deep Sediments of the Mississippi Embayment Using Surface Wave and Spectral Ratio Methods written by Jonathan Pqul Bailey and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deep soils of the Mississippi Embayment in the central United States will have a significant influence on earthquake ground motions generated by the New Madrid Seismic Zone. The seismic properties of these soils, which extend to depths of over 1000 meters in some areas, are poorly characterized at depths below 60 to 100 meters. This study presents shear wave velocity (Vs) profiles determined from Spectral-Analysis-of-Surface-Waves (SASW) measurements performed at eleven sites in Arkansas, Tennessee, and Missouri. These measurements were performed using the low-frequency field vibrator developed as part of the NSF Network for Earthquake Engineering Simulation (NEES) program. Shear wave velocity profiles were developed to depths of approximately 220 meters at eleven sites located throughout the Mississippi Embayment. In addition to the SASW measurements, ambient noise measurements of horizontal and vertical ground motions were performed to estimate the average Vs over the full profile depth using the H/V spectral ratio method. The Vs profiles derived from the SASW measurements compared well with Vs reference profiles that have been developed for the Mississippi Embayment and used in recent site response studies of the region. The observed variability of the profiles was found to be in general agreement with past assumptions used for the deep soil and correlated with changes in soil lithology. Relationships between the soil formations and Vs were consistent with past studies and provided information to greater depths. Lastly the H/V spectral ratio measurements were successfully applied at each of the eleven sites, but appeared to overestimate the average Vs.

Download or read book Treatise on Seismicity and Velocity Structure of the Northern Mississippi Embayment written by Akramalsadat Mostafanejad and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismicity of the New Madrid seismic zone, velocity structure of the northern Mississippi Embayment and extent of lithospheric discontinuities have been investigated in this work. Spatial variations of seismic b-value in the NMSZ have been determined. A region of high b-value (b1̃.8) in the northern segment of the Reelfoot fault has been found which reflects higher frequency in the occurrence rate of small earthquakes. This is attributed to fault creep in a medium with high silica content, high pore fluid pressure and extensive velocity heterogeneity. In another study, power spectral ratios of horizontal to vertical (H/V) and vertical to horizontal (V/H) components of teleseismic P-waves recorded by broadband seismic stations inside the Mississippi embayment have been examined to produce a 3-D average velocity map of the sediments. Fundamental resonance frequencies for S-wave reverberations in the northern Mississippi Embayment are about 0.2 to 0.4 Hz. Detailed linear gradient velocity models for Vp and Vs have also been calculated using teleseismic vertical and radial transfer functions at 60 broadband stations inside the Mississippi embayment and simultaneously inverting for velocity parameters. This led to a detailed 3-D linear gradient Vp and Vs model of the sediments for the first time. P-wave velocity starts at about 1.0 km/s near the surface and increases with depth to 3.5 to 4 km/s in deeper parts of the embayment. S-wave velocities vary from 0.3km/s to 1.6 km/s in deeper sections to the southwest. This detailed velocity structure of the unconsolidated sediments is developed so that it could be used to downward continue the transfer functions to the depth of 5 km to remove the effects of observed amplification, reverberation and large P-S conversions that occurs at the sediment-bedrock interface. The resulting waveforms are depth migrated to image the lateral and vertical changes of major reflectors with depth. The Moho boundary is observed with high resolution at depths of 45 to 55 km in the study area.

Download or read book Probabilistic Seismic Hazard Mapping of the Mississippi Embayment Including the Effect of Soil Conditions written by Gabriel R. Toro and published by . This book was released on 1992 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismic Ground Response Analysis written by Nozomu Yoshida and published by Springer. This book was released on 2014-11-17 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents state-of-the-art information on seismic ground response analysis, and is not only very valuable and useful for practitioners but also for researchers. The topics covered are related to the stages of analysis: 1. Input parameter selection, by reviewing the in-situ and laboratory tests used to determine dynamic soil properties as well as the methods to compile and model the dynamic soil properties from literature;2. Input ground motion; 3. Theoretical background on the equations of motion and methods for solving them; 4. The mechanism of damping and how this is modeled in the equations of motions; 5. Detailed analysis and discussion of results of selected case studies which provide valuable information on the problem of seismic ground response analysis from both a theoretical and practical point of view.

Download or read book Seismological Research Letters written by and published by . This book was released on 2006 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variations in the Seismic Quality Factor Q for the Mississippi Embayment Sediments Utilizing Spectral Analysis of Reflection Data written by Michael Wilson Towle and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A natural log spectral ratio technique is used to calculate Qp for the post-Paleozoic, unconsolidated sediments of the northern Mississippi Embayment. The method is applied to high-resolution marine seismic reflection data acquired along the Mississippi River. The method assumes a frequency independent Q over a certain frequency band. The frequency bands inspected range from 10-150 Hz and 10-200 Hz based on observed linear trends in the spectral ratio data. The large volume of data available allows for increased accuracy in Q estimates. Values of Qs are then approximated using an empirical Qp/Qs relationship for the embayment. Results show that average Qp=100-160 and average Qs=50-80. These values are nearly twice those calculated in previous studies, therefore suggesting that attenuation within the unconsolidated sediment column may not cancel out site amplification effects. These effects have important implications for seismic hazards and ground displacement predictions in the Central U.S. region.

Download or read book Understanding Seismic Velocity Structure and Its Time varying Process Beneath the Mississippi Embayment Through Ambient Noise Analysis written by Chunyu Liu and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We apply ambient noise analysis to image shear wave velocity from near surface to uppermost mantle beneath the Mississippi embayment, and investigate the crustal response to climatological loadings. To further understand the generation mechanism of microseisms, we explore the azimuthal distribution of the signal-to-noise ratio and amplitude difference of crustal surface waves and estimate possible source locations in the ocean through back- projections.A shear wave velocity model with 0.5 0.5 resolution for the crust and uppermost mantle has been determined. We take advantage of the dense coverage and long-term deployments of 277 3-component broadband stations installed from 1990 to 2018 to image the shear wave velocity. Rayleigh group velocity dispersion curves extracted from ambient noise are inverted to obtain shear wave velocity at 5, 12, 24, and 43 km. We find that low velocity features characterize the Reelfoot Graben, Rough Creek Graben, Black Warrior basin, and southern Mississippi embayment in the upper 5 km of crust. High velocity features characterize the Ozark plateau, Ouachita mountains and Nashville dome. From 5 to 12 km, a low velocity anomaly is associated with the Missouri batholith. From 12 to 24 km, high velocity features characterize the Reelfoot-Rough Creek graben, and along the Appalachian-Ouachita thrust front. From 24 to 43 km, high velocity anomalies are commonly observed in the Mississippi embayment, and spatially correlated with the crustal thickness.Cross-correlation of the ambient seismic field is also used to estimate seasonal seismic velocity variations and to determine the underlying physical mechanisms. We process continuously recorded broadband data from 53 stations in 2014 to obtain daily and yearly cross- correlations and measure the Rayleigh wave phase velocity change over 4 frequency bands, 0.3-1, 0.5-1.2, 0.7-1.5, and 1-2 Hz. We then calculate the correlation coefficients between the velocity variations and the precipitation, water table fluctuation, temperature, atmospheric pressure and wind speed to find which external variable correlates most strongly with the observed changes. We observe high t/t (a proxy for velocity variation), the slowest velocity relative to annual average, from May to July and low t/t in September/October, and find the t/t variations correlate primarily with water table fluctuation. The correlation coefficients between water table fluctuation and t/t are independent of the interstation distance and frequency, but high coefficients are observed more often in the 0.3-1 Hz than 1-2 Hz band probably because high-frequency coherent signals attenuate faster than low-frequency ones. The t/t variations lag behind the water table fluctuation by about 20 days, which suggests the velocity changes can be attributed to the pore pressure diffusion effect. The maximum t/t variations decrease with frequency from 0.03% at 0.3-1 Hz to 0.02% at 1-2 Hz, and the differences between them might be related to different local sources or incident angles. The seasonal variations of t/t are azimuthally independent, and a large increase of noise amplitude only introduces a small increase to the t/t variation. The maximum t/t variations non-linearly decrease with the distance, which could be associated with the attenuation of coherent noise. At close distances, the maximum t/t holds a wide range of values, which is likely related to local structure. At larger distances, velocity variations sample a larger region so that it stabilizes to a more uniform value. We find that the observed changes in wave speed are in agreement with the prediction of a poroelastic model.The source distribution of ambient noise is of fundamental importance to understanding the generation mechanism of microseisms. Cross-correlations of ambient seismic noise from 277 broadband stations with at least 1-month recording between 1990 and 2018 are used to estimate source locations of primary and secondary microseisms inside the Mississippi embayment. We investigate source locations by analyzing the azimuthal distribution of the signal-to-noise ratio (SNR) and amplitude difference of crustal surface wave arrivals and by 2D F-K analysis. We also use 84 stations with continuous 1-year recording to explore seasonal variations of SNRs of the surface wave, which could be used to locate active sources in different seasons. We observe that (1) four azimuths could be identified in the azimuthal distribution of SNRs and reflect four different energy sources. Two energy sources are active in the Pacific and Atlantic ocean of northern hemisphere during winter and two relatively weak sources are active near Australia and South America in the southern hemisphere during summer. (2) Primary microseisms originate along the coastlines of southern Australia, Canada and Alaska, Newfoundland, and northeast South America. (3) Secondary microseisms could be generated in the deep water of northern and southern Pacific ocean, along coastlines of Canada and Alaska associated with reflections, and in the deep water of south of Greenland. (4) Azimuthal distribution of SNRs of sediment surface waves observed at 1-5s is negatively correlated with the geometry of the edge of the Mississippi embayment. The sediment surface waves could be induced by the basin-edge..

Download or read book Dynamic Geotechnical Testing II written by Ronald J. Ebelhar and published by ASTM International. This book was released on 1994 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: