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  Subjects -> EARTH SCIENCES (Total: 587 journals)
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EARTH SCIENCES (434 journals)            First | 1 2 3 4 5     

Natural Hazards     Hybrid Journal   (Followers: 179)
Natural Hazards and Earth System Sciences (NHESS)     Open Access   (Followers: 7)
Natural Hazards Review     Full-text available via subscription   (Followers: 7)
Natural Resources Research     Hybrid Journal   (Followers: 4)
Nature Geoscience     Full-text available via subscription   (Followers: 167)
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen     Full-text available via subscription   (Followers: 3)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 3)
New Journal of Physics     Open Access   (Followers: 7)
Newsletters on Stratigraphy     Full-text available via subscription   (Followers: 6)
Nonlinear Processes in Geophysics (NPG)     Open Access   (Followers: 3)
Ocean & Coastal Management     Hybrid Journal   (Followers: 146)
Ocean Development & International Law     Hybrid Journal   (Followers: 11)
Ocean Dynamics     Hybrid Journal   (Followers: 5)
Ocean Engineering     Hybrid Journal   (Followers: 3)
Ocean Modelling     Hybrid Journal   (Followers: 4)
Ocean Science (OS)     Open Access   (Followers: 6)
Ocean Science Discussions (OSD)     Open Access   (Followers: 5)
Ocean Science Journal     Hybrid Journal   (Followers: 3)
Open Journal of Soil Science     Open Access   (Followers: 4)
Ore Geology Reviews     Hybrid Journal   (Followers: 3)
Organic Geochemistry     Hybrid Journal   (Followers: 7)
Osterreichische Wasser- und Abfallwirtschaft     Hybrid Journal  
Paläontologische Zeitschrift     Hybrid Journal   (Followers: 3)
Papers on Global Change IGBP     Open Access   (Followers: 1)
Permafrost and Periglacial Processes     Hybrid Journal   (Followers: 3)
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Photogrammetrie - Fernerkundung - Geoinformation     Full-text available via subscription  
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Physics in Medicine & Biology     Full-text available via subscription   (Followers: 7)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
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Physics of the Earth and Planetary Interiors     Hybrid Journal   (Followers: 10)
Physics of the Solid State     Hybrid Journal   (Followers: 3)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics World     Full-text available via subscription   (Followers: 3)
Physik in unserer Zeit     Hybrid Journal  
Pirineos     Open Access  
Planet     Open Access  
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 2)
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Polish Polar Research     Open Access   (Followers: 4)
Positioning     Open Access   (Followers: 1)
Pramana     Open Access   (Followers: 8)
Precambrian Research     Hybrid Journal   (Followers: 5)
Preview     Hybrid Journal  
Procedia Earth and Planetary Science     Open Access   (Followers: 4)
Proceedings in Marine Science     Full-text available via subscription   (Followers: 3)
Proceedings of the Geologists' Association     Full-text available via subscription   (Followers: 3)
Proceedings of the Linnean Society of New South Wales     Full-text available via subscription   (Followers: 1)
Proceedings of the Yorkshire Geological Society     Hybrid Journal  
Pure and Applied Geophysics     Hybrid Journal   (Followers: 8)
Quarterly Journal of Engineering Geology and Hydrogeology     Hybrid Journal   (Followers: 5)
Quaternary Australasia     Full-text available via subscription  
Quaternary Geochronology     Hybrid Journal   (Followers: 4)
Quaternary International     Hybrid Journal   (Followers: 9)
Quaternary Research     Full-text available via subscription   (Followers: 15)
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Radiocarbon     Open Access   (Followers: 2)
Raumforschung und Raumordnung     Hybrid Journal  
Remote Sensing     Open Access   (Followers: 12)
Remote Sensing Letters     Hybrid Journal   (Followers: 8)
Remote Sensing Science     Open Access   (Followers: 2)
Rendiconti Lincei     Hybrid Journal  
Reports on Mathematical Physics     Full-text available via subscription  
Reports on Progress in Physics     Full-text available via subscription   (Followers: 2)
Resource Geology     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Full-text available via subscription  
Reviews of Modern Physics     Full-text available via subscription   (Followers: 16)
Revista Boletín Ciencias de la Tierra     Open Access   (Followers: 2)
Revista Brasileira de Geofísica     Open Access   (Followers: 4)
Revista de Ingenieria Sismica     Open Access  
Revista de la Sociedad Entomologica Argentina     Open Access   (Followers: 2)
Revista de Topografía Azimut     Open Access   (Followers: 1)
Revista Eletrônica Científica Inovação e Tecnologia     Open Access  
Revista Geológica de Chile     Open Access   (Followers: 2)
River Systems     Full-text available via subscription   (Followers: 3)
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 4)
Rocks & Minerals     Hybrid Journal   (Followers: 2)
Russian Geology and Geophysics     Hybrid Journal   (Followers: 2)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Journal of Pacific Geology     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal  
Science China Earth Sciences     Hybrid Journal   (Followers: 2)
Science News     Hybrid Journal   (Followers: 15)
Scientific Annals of Stefan cel Mare University of Suceava. Geography Series     Open Access  
Scientific Journal of Earth Science     Open Access  
Scientific Reports     Open Access   (Followers: 10)
Scottish Journal of Geology     Hybrid Journal   (Followers: 5)
Sedimentary Basins of the World     Full-text available via subscription   (Followers: 2)
Sedimentary Geology     Hybrid Journal   (Followers: 11)
Sedimentology     Hybrid Journal   (Followers: 10)
Seismic Instruments     Hybrid Journal   (Followers: 1)
Seismological Research Letters     Full-text available via subscription   (Followers: 2)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 7)
Solid Earth     Open Access   (Followers: 3)
Solid Earth Discussions     Open Access   (Followers: 1)
Southern Forests: a Journal of Forest Science     Hybrid Journal   (Followers: 4)
Standort - Zeitschrift für angewandte Geographie     Hybrid Journal   (Followers: 1)

  First | 1 2 3 4 5     

Journal Cover Soil Dynamics and Earthquake Engineering
   [9 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0267-7261
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.116]   [H-I: 39]
  • Scoping prediction of re-radiated ground-borne noise and vibration near
           high speed rail lines with variable soils
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): D.P. Connolly , G. Kouroussis , P.K. Woodward , A. Giannopoulos , O. Verlinden , M.C. Forde
      This paper outlines a vibration prediction tool, ScopeRail, capable of predicting in-door noise and vibration, within structures in close proximity to high speed railway lines. The tool is designed to rapidly predict vibration levels over large track distances, while using historical soil information to increase accuracy. Model results are compared to an alternative, commonly used, scoping model and it is found that ScopeRail offers higher accuracy predictions. This increased accuracy can potentially reduce the cost of vibration environmental impact assessments for new high speed rail lines. To develop the tool, a three-dimensional finite element model is first outlined capable of simulating vibration generation and propagation from high speed rail lines. A vast array of model permutations are computed to assess the effect of each input parameter on absolute ground vibration levels. These relations are analysed using a machine learning approach, resulting in a model that can instantly predict ground vibration levels in the presence of different train speeds and soil profiles. Then a collection of empirical factors are coupled with the model to allow for the prediction of structural vibration and in-door noise in buildings located near high speed lines. Additional factors are also used to enable the prediction of vibrations in the presence of abatement measures (e.g. ballast mats and floating slab tracks) and additional excitation mechanisms (e.g. wheelflats and switches/crossings).


      PubDate: 2014-07-28T20:51:35Z
       
  • Time-harmonic response of transversely isotropic multilayered half-space
           in a cylindrical coordinate system
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Zhi Yong Ai , Zhi Xiong Li
      With the aid of the analytical layer-element method, a comprehensive analytical derivation of the response of transversely isotropic multilayered half-space subjected to time-harmonic excitations is presented in a cylindrical coordinate system. Starting with the governing equations of motion and the constitutive equations of transversely isotropic elastic body, and based on the Fourier expansion, Hankel and Laplace integral transform, analytical layer-elements for a finite layer and a half-space are derived. Considering the continuity conditions on adjacent layers׳ interfaces and the boundary conditions, the global stiffness matrix equations for multilayered half-space are assembled and solved. Finally, some numerical examples are given to make a comparison with the existing solution and to demonstrate the influence of parameters on the dynamic response of the medium.


      PubDate: 2014-07-28T20:51:35Z
       
  • Collapse of Showa Bridge during 1964 Niigata earthquake: A quantitative
           reappraisal on the failure mechanisms
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): S. Bhattacharya , K. Tokimatsu , K. Goda , R. Sarkar , M. Shadlou , M. Rouholamin
      Collapse of Showa Bridge during the 1964 Niigata earthquake has been, over many years, an iconic case study for demonstrating the devastating effects of liquefaction. Inertial forces during the initial shock (within the first 7s of the ground shaking) or lateral spreading of the surrounding ground (which started at 83s after the start of the shaking) cannot explain the failure of Showa Bridge as the bridge failed at about 70s following the main shock and before the lateral spreading of the ground started. In this study, quantitative analysis is carried out for various failure mechanisms that may have contributed to the failure. The study shows that at about 70s after the onset of the earthquake shaking, the increased natural period of the bridge (due to the elongation of unsupported length of the pile caused by soil liquefaction) tuned with the period of the liquefied ground causing resonance between the bridge and the ground motion. This tuning effect (resonance) caused excessive deflection at the pile head, resulting in unseating of the bridge deck from the supporting pier and thereby initiating the collapse of the bridge.


      PubDate: 2014-07-28T20:51:35Z
       
  • SSI in steel frames subjected to near-fault earthquakes
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): G. Minasidis , G.D. Hatzigeorgiou , D.E. Beskos
      Modern seismic codes are usually associated with far-field earthquakes and generally neglect soil–structure interaction, assuming that omission of this phenomenon leads to conservative results. This study investigates the effect of soil–structure interaction on the inelastic response of two-dimensional steel frames subjected to near-fault earthquakes, which have been recorded near to seismic faults with reverse and strike–slip mechanisms. In order to achieve this, thirty-six planar moment resisting steel frames which have been designed for seismic and vertical loads according to European codes are examined under the action of sixty near-fault pulse-like records. Simplified soil–structure interaction is carried out using springs and dashpots to simulate the flexibility of soil at the soil–foundation interface and adopting the effective properties of soil. Seismic response parameters, such as, interstorey drift ratios, maximum floor accelerations and inelastic displacement ratios are numerically determined by dynamic inelastic analyses. After a comprehensive statistical analysis, empirical expressions for these parameters in terms of the number of storeys of structures, the type of fault mechanism as well as the consideration or not of soil–structure interaction are obtained. Critical examination of the results indicates that the flexibility of soil strongly affects the seismic response of steel frames. Furthermore, it is concluded that the structural response parameters under consideration are noticeably influenced by the type of fault mechanism.


      PubDate: 2014-07-28T20:51:35Z
       
  • Effect of dynamic soil–bridge interaction modeling assumptions on
           the calculated seismic response of integral bridges
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Semih Erhan , Murat Dicleli
      In this study, the effect of soil–structure modeling assumptions and simplifications on the seismic analyses results of integral bridges (IBs) is investigated. For this purpose, five structural models of IBs are built in decreasing levels of complexity starting from a nonlinear structural model including close numerical simulation of the behavior of the foundation and backfill soil and gradually simplifying the model to a level where the effect of backfill and foundation soil is totally excluded. Nonlinear time history analyses of the modeled IBs are then conducted using a set of ground motions with various intensities representing small, medium and large intensity earthquakes. The analyses results are then used to assess the effect of modeling complexity level on the calculated seismic response of IBs. The nonlinear soil-bridge interaction modeling assumptions are found to have considerable effects on the calculated seismic response of IBs under medium and large intensity earthquakes.


      PubDate: 2014-07-28T20:51:35Z
       
  • Effects of spatial variability of soil properties on the seismic response
           of an embankment dam
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Heidy Sanchez Lizarraga , Carlo G. Lai
      In this paper a numerical procedure for a two-dimensional seismic analysis of an embankment dam is presented taking into account the spatial variability of soil properties. The approach integrates advanced numerical modelling and random field theory into a probabilistic framework. Geotechnical parameters are modelled as anisotropic random fields with different autocorrelation distances in the vertical and horizontal directions. The correlation between cohesion and friction angle values is taken into account with Gaussian cross-correlated random fields using a specific marginal distribution, autocorrelation functions and cross-correlation coefficients. Based on this stochastic representation of the soil domain, fully nonlinear time-history analyses are carried out for several earthquake records of varying intensities. The results of the analyses are used to explicitly derive fragility functions that include the influence of spatial variability of soil parameters and the uncertainty of ground motion.


      PubDate: 2014-07-28T20:51:35Z
       
  • Rectangular footing on soil with depth-degrading stiffness: Vertical and
           rocking impedances under conditional existence of surface waves
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Christos Vrettos
      The response of rectangular rigid footings resting on an elastic soil of shear modulus decreasing monotonically with depth is studied. Such profiles are typically encountered after ground improvement. The propagation characteristics of SV/P surface waves are investigated, showing the appearance of cut-off frequencies above which surface waves do not exist. The semi-analytical method of the subdivision of the footing/soil contact area is then used for solving the boundary value problem, whereby the influence functions for the sub-regions are determined by integration of the corresponding surface-to-surface Green׳s functions. Impedance functions are presented over a wide range of frequencies for typical values of the non-homogeneity parameters, the Poisson׳s ratio and the foundation geometry. The salient features that are associated with the non-homogeneity and the appearance of cut-off frequencies are elucidated.


      PubDate: 2014-07-28T20:51:35Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64




      PubDate: 2014-07-28T20:51:35Z
       
  • A numerical study on the 2D behavior of clayey basins
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): H. Khanbabazadeh , R. Iyisan
      In this numerical study the effects of basin edge on the dynamic behavior of the clayey basins are investigated. For this purpose a range of bedrock inclinations at the valley sides from slighter 10° and 20° to steeper 30° and 40°, and three types of stiff, medium plasticity and soft clay materials are selected. The results of the 2D analyses show that not only the amplification pattern of different clay types is different, but also it differs for each material type under different motion intensities. Also, the frequency domain results show that different parts of the valleys are sensitive to different periods. It was seen that under two-dimensional conditions the amplification of clay types other than soft clay could be higher. Finally, the results of this research show the important effect of motion intensity on the 2D behavior of valleys.


      PubDate: 2014-07-28T20:51:35Z
       
  • Numerical study on screening of surface waves using a pair of softer
           backfilled trenches
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Ankurjyoti Saikia
      Vibration screening effectiveness of a pair of in-filled trenches is numerically studied under conditions of plane strain using PLAXIS 2D in a linear elastic, isotropic, and homogeneous half-space acted upon by a steady-state vertical excitation. Barrier efficiency is analyzed in terms of reduction of vertical and horizontal vibration components with respect to the variations in barrier geometry and in-fill material parameters. The geometric features are normalized with respect to Rayleigh wavelength of vibration in soil. The in-fill trench material is considered to be softer and accordingly assigned lower shear wave velocities than the half-space. Non-dimensional design charts are developed and the key parameters participating in wave screening process are identified. Some recommendations are made regarding the optimal selection of these parameters. Comparison with a few published results shows close agreement. Such an isolation scheme may be advantageous in circumstances where a single trench requires unrealistic depth.


      PubDate: 2014-07-28T20:51:35Z
       
  • Development of elasto-plastic viscous damper finite element model for
           reinforced concrete frames
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): F. Hejazi , A. Zabihi , M.S. Jaafar
      By advancing the technologies regarding seismic control of structures and development of earthquake resistance systems in the past decades application of different types of earthquake energy dissipation system has incredibly increased. Viscous damper device as a famous and the simplest earthquake energy dissipation system is implemented in many new structures and numerous number of researches have been done on the performance of viscous dampers in structures subjected to earthquake. The experience of recent severe earthquakes indicates that sometimes the earthquake energy dissipation devices are damaged during earthquakes and there is no function for structural control system. So, damage of earthquake energy dissipation systems such as viscous damper device must be considered during design of earthquake resistance structures. This paper demonstrates the development of three-dimensional elasto-plastic viscous damper element consisting of elastic damper in the middle part and two plastic hinges at both ends of the element which are compatible with the constitutive model to reinforce concrete structures and are capable to detect failure and damage in viscous damper device connections during earthquake excitation. The finite element model consists of reinforced concrete frame element and viscous damper element is developed and special finite element algorithm using Newmark׳s direct step-by-step integration is developed for inelastic dynamic analysis of structure with supplementary elasto-plastic viscous damper element. So based on all the developed components an especial finite computer program has been codified for “Nonlinear Analysis of Reinforced Concrete Buildings with Earthquake Energy Dissipation System”. The evaluation of seismic response of structure and damage detection in structural members and damper device was carried out by 3D modeling, of 3 story reinforced concrete frame building under earthquake multi-support excitation.


      PubDate: 2014-07-28T20:51:35Z
       
  • Quantifying the epistemic uncertainty in ground motion models and
           prediction
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): R. Foulser-Piggott
      The aim of this paper is to compute the ground-motion prediction equation (GMPE)-specific components of epistemic uncertainty, so that they may be better understood and the model standard deviation potentially reduced. The reduced estimate of the model standard deviation may also be more representative of the true aleatory uncertainty in the ground-motion predictions. The epistemic uncertainty due to input variable uncertainty and uncertainty in the estimation of the GMPE coefficients are examined. An enhanced methodology is presented that may be used to analyse their impacts on GMPEs and GMPE predictions. The impacts of accounting for the input variable uncertainty in GMPEs are demonstrated using example values from the literature and by applying the methodology to the GMPE for Arias Intensity. This uncertainty is found to have a significant effect on the estimated coefficients of the model and a small effect on the value of the model standard deviation. The impacts of uncertainty in the GMPE coefficients are demonstrated by quantifying the uncertainty in hazard maps. This paper provides a consistent approach to quantifying the epistemic uncertainty in hazard maps using Monte Carlo simulations and a logic tree framework. The ability to quantify this component of epistemic uncertainty offers significant enhancements over methods currently used in the creation of hazard maps as it is both theoretically consistent and can be used for any magnitude–distance scenario.


      PubDate: 2014-07-28T20:51:35Z
       
  • A viscous-spring transmitting boundary for cylindrical wave propagation in
           saturated poroelastic media
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Peng Li , Er-xiang Song
      Based on the u–U formulation of Biot equation and the assumption of zero permeability coefficient, a viscous-spring transmitting boundary which is frequency independent is derived to simulate the cylindrical elastic wave propagation in unbounded saturated porous media. By this viscous-spring boundary the effective stress and pore fluid pressure on the truncated boundary of the numerical model are replaced by a set of spring, dashpot and mass elements, and its simplified form is also given. A u–U formulation FEA program is compiled and the proposed transmitting boundaries are incorporated therein. Numerical examples show that the proposed viscous-spring boundary and its simplified form can provide accurate results for cylindrical elastic wave propagation problems with low or intermediate values of permeability or frequency content. For general two dimensional wave propagation problems, spuriously reflected waves can be greatly suppressed and acceptable accuracy can still be achieved by placing the simplified boundary at relatively large distance from the wave source.


      PubDate: 2014-07-28T20:51:35Z
       
  • Numerical modelling of wave propagation in anisotropic soil using a
           displacement unit-impulse-response-based formulation of the scaled
           boundary finite element method
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Xiaojun Chen , Carolin Birk , Chongmin Song
      An efficient method for modelling the propagation of elastic waves in unbounded domains is developed. It is applicable to soil–structure interaction problems involving scalar and vector waves, unbounded domains of arbitrary geometry and anisotropic soil. The scaled boundary finite element method is employed to derive a novel equation for the displacement unit-impulse response matrix on the soil–structure interface. The proposed method is based on a piecewise linear approximation of the first derivative of the displacement unit-impulse response matrix and on the introduction of an extrapolation parameter in order to improve the numerical stability. In combination, these two ideas allow for the choice of significantly larger time steps compared to conventional methods, and thus lead to increased efficiency. As the displacement unit-impulse response approaches zero, the convolution integral representing the force–displacement relationship can be truncated. After the truncation the computational effort only increases linearly with time. Thus, a considerable reduction of computational effort is achieved in a time domain analysis. Numerical examples demonstrate the accuracy and high efficiency of the new method for two-dimensional soil–structure interaction problems.


      PubDate: 2014-07-28T20:51:35Z
       
  • Cyclic response of masonry infilled RC frames: Experimental results and
           simplified modeling
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Liborio Cavaleri , Fabio Di Trapani
      The recent large interest in nonlinear seismic analysis methods, static and dynamic, has required proper strategies of modeling based on reliable, and at the same time easy to use, constitutive laws for the structural elements. Regarding the behavior of framed structures, special attention has to be devoted to infills because of the key role they play in modifying overall stiffness, strength and ductility under seismic excitation. Pointing out the attention on this topic the paper discusses a criteria for modeling the structural behavior of infills based on a macromodeling approach, that is to say on the substitution of infills with diagonal pin jointed struts. Is here shown how multilinear plastic link elements governed by a hysteretic Pivot model, available in different FEM codes, can be appropriately used to model the equivalent struts to perform linear or nonlinear analyses. In order to enlarge experimental knowledge on cyclic behavior of infilled frames structures and as reference for developing the above mentioned modeling strategy, an experimental campaign on single-storey, single-bay, fully infilled frames with different kinds of masonry and subjected to lateral cyclical loads, was carried out, and some others available in the literature are referred to. Validation of Pivot modeling approach was carried out comparing experimental results and computer simulations of the experimental tests. In the paper hysteresis parameters values calibrating Pivot law are also given for involved masonry infills typologies and some proposals for correlation between strength and stiffness of infilled frames and of masonry infills are provided as a tool for the quick calibration of the Pivot model in practical applications.


      PubDate: 2014-07-28T20:51:35Z
       
  • Mean refracted ray path method for reliable downhole seismic data
           interpretations
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Eun-Seok Bang , Seong-Jun Cho , Dong-Soo Kim
      The downhole seismic method is one of the most widely used field seismic methods because it is cost-effective and simple to operate compared to other borehole methods. For the interpretation of the data, the direct method is generally used, but this method determines the V S profile roughly and requires an interpreter׳s subjective interpretation. To evaluate the V S profile in detail, the refracted ray path method is used. However, the V S profiles evaluated by these methods often show meaningless repetitive fluctuations with depth and it is because the estimated travel time data is somewhat inaccurate. In this paper, the mean refracted ray path method (MRM), which combines the advantages of both the direct method and the refracted ray path method, is proposed. It provides the V S profile more reliably and automatically. The travel time data is corrected based on the refracted ray path and the R 2 value of the regression curve is employed for automation. To verify the proposed method, the synthetic travel time data were generated by forward modeling based on Snell׳s law with some amount of random error added. As the amount of random error increased, the meaningless repetitive fluctuations in the V S profile determined by the conventional methods also increased. On the other hand, the V S profiles determined by the MRM matched the model well and the superiority of the proposed method was thus noted. Finally, the proposed method was applied for the data reduction of several instances of field data. The determined V S profiles were compared with the drilling logs, the SPT-N values, and/or the CPT result, and the reliability and applicability of the MRM was thus verified.


      PubDate: 2014-07-28T20:51:35Z
       
  • Effect of preloading on the amplification characteristics of soil profiles
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Constantine A. Stamatopoulos
      Preloading is a temporary loading, usually an embankment, applied to improve subsurface soils by densification. This paper studies the effect of preloading on the amplification characteristics of soft sites with an elaborate parametric analysis. The soil type, the depth of the bedrock, the water table depth, the level of preloading, the applied earthquake, the shear wave velocity of the bedrock and the shear modulus and damping versus shear strain relations were varied in a systematic manner. The analysis was performed by the commonly used one-dimensional equivalent-linear dynamic method. The shear wave velocity versus depth and the effect of preloading on shear velocity are computed with well-established soil mechanics equations. The results illustrated that the seismic response at the top of the profile generally decreases as a result of preloading. A more detailed analysis of results shows that the effect of preloading on the seismic response depends on the soil type and the depth of the bedrock. Based on these results, a method is proposed by which a practicing engineer involved with improvement of soft ground can simulate the effect of preloading on the seismic motion.


      PubDate: 2014-07-28T20:51:35Z
       
  • Factors affecting shear modulus degradation of cement treated clay
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): P. Subramaniam , Subhadeep Banerjee
      Cement stabilization is often used to improve the bearing capacity and compressibility of soft clays. The present paper aims to investigate the shear modulus degradation of cement treated clay during cyclic loading. A series of cyclic triaxial test was conducted on artificially cement treated marine clay to study the factors affecting the shear modulus degradation. The parameters considered for the study are cement content (2.5–7.5%), curing days (7–28), cyclic shear strain amplitude (0.3–1%), number of loading cycles (1–100) and loading frequency (0.1–0.5Hz). As in the case of natural clays, cement treated clays exhibit stiffness degradation which depends on mix ratio, curing days and loading conditions. The results show that the shear modulus degradation decreases with increase in the shear strain amplitude, cement content and curing days. It is also noted that irrespective of the mix ratio and curing conditions, the degradation decreases with increase in loading frequency. An empirical relationship is proposed to predict the shear modulus degradation based on Idriss׳s degradation model. The performance of the proposed empirical model is validated with the present experimental results.


      PubDate: 2014-07-28T20:51:35Z
       
  • Dynamic soil–structure interaction analysis of a telescope at the
           Javalambre Astrophysical Observatory
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Stijn François , Pedro Galvín , Pedro Museros , Geert Lombaert , Geert Degrande
      This paper presents the dynamic soil–structure analysis of the main telescope T250 of the Observatorio Astrofísico de Javalambre (OAJ, Javalambre Astrophysical Observatory) on the Pico del Buitre. Vibration control has been of prime concern in the design, since astrophysical observations may be hindered by mechanical vibration of optical equipment due to wind loading. The telescope manufacturer therefore has imposed a minimal natural frequency of 10Hz for the supporting telescope pier. Dynamic soil–structure interaction may significantly influence the lowest natural frequency of a massive construction as a telescope pier. The structure clamped at its base has a resonance frequency of 14.3Hz. A coupled finite element–boundary element (FE–BE) model of the telescope pier that accounts for the dynamic interaction of the piled foundation and the soil predicts a resonance frequency of 11.2Hz, demonstrating the significant effect of dynamic soil–structure interaction. It is further investigated to what extent the coupled FE–BE model can be simplified in order to reduce computation time. The assumption of a rigid pile cap allows us to account for dynamic soil–structure interaction in a simplified way. A coupled FE–BE analysis with a rigid pile cap predicts a resonance frequency of 11.7Hz, demonstrating a minor effect of the pile cap flexibility on the resonance frequency of the telescope pier. The use of an analytical model for the pile group results in an overestimation of the dynamic soil stiffness. This error is due to the large difference between the actual geometry and the square pile cap model for which the parameters have been tuned.


      PubDate: 2014-07-28T20:51:35Z
       
  • Centrifuge modeling of interaction between reverse faulting and tunnel
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Mohammad Hassan Baziar , Ali Nabizadeh , Chung Jung Lee , Wen Yi Hung
      In this study, a series of centrifuge tests, modeling reverse fault rupture with 60° dip angle, were conducted in a dry sandy soil with a tunnel embedded in the soil layer. The test results showed that the tunnel and soil responses depended on the tunnel position, soil relative density and tunnel rigidity. Tunnels appeared be able to deviate the fault rupture path, while this deviation may be associated with significant rotation and displacement of the tunnel. However, a deeper tunnel was able to diffuse the shear deformation to a wider zone with an unsmooth surface displacement which may cause severe damage to the surface structures. Finally, the tunnel rotation, the location of the fault outcropping, the vertical displacement of the ground surface, the effect of tunnel rigidity on fault rupture path and surface displacement and the effect of soil relative density on fault–tunnel interaction were reported and discussed in this study.


      PubDate: 2014-07-28T20:51:35Z
       
  • Effect of non-plastic silt content on the liquefaction behavior of
           sand–silt mixture
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Mohammad Emdadul Karim , Md. Jahangir Alam
      To identify the effect of non-plastic silt on the cyclic behavior of sand–silt mixtures, total sixty undrained cyclic triaxial stress-control tests were carried out on sand–silt mixtures. These tests were conducted on specimens of size 71mm diameter and 142mm height with a frequency of 1Hz. Specimens were prepared at a constant relative density and constant density approach. The effect of relative density, confining pressure as well as magnitude of cyclic loading was also studied. For a constant relative density (Dr=60%) the effect of limiting silt content, pore pressure response and cyclic strength was observed. The rate of generation of excess pore water pressure with respect to cycles of loading was found to initially increase with increase in silt content till the limiting silt content and thereafter it reverses its trend when the specimens were tested at a constant relative density. The cyclic resistance behavior was observed to be just opposite to the pore pressure response. Permeability, CRR and secant shear modulus decreased till limiting silt content; after that they became constant with increasing silt content.


      PubDate: 2014-07-28T20:51:35Z
       
  • Identification of the structural model and analysis of the global seismic
           behaviour of a RC damaged building
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Antonio Di Cesare , Felice Carlo Ponzo , Marco Vona , Mauro Dolce , Angelo Masi , Maria Rosaria Gallipoli , Marco Mucciarelli
      The study of the structural behaviour of damaged RC buildings during ground motion is a fundamental topic in the modern earthquake engineering. Many studies have been carried out in order to better understand the real evolution of the damage in RC buildings during a seismic event. In this work, a damaged RC building has been intensively investigated in terms of materials property and stiffness evolution in order to interpreting the structural and nonstructural surveyed damage. The peculiarity of this building is its damage sequence during the 2002 Molise earthquake. In fact, the town of Bonefro suffered moderate damage (MCS intensity VII), with the exception of the investigated reinforced concrete building. The October 31, 2002 event (M=5.4) caused some structural damage to this building. The second event (M=5.3), on November 1, 2002, increased substantially the damage level (grade 4 according to the 1998 European Macroseismic Scale). It occurred just while, due to fortuitous circumstances, a 5min. seismic velocimetric recording was being taken. The working group has performed some frequency analyses based on the recording. Several non linear models have been defined to understand the damage evolution of the building and the local and global damage patterns through for static analyses. Finally, linear and non linear models have been developed with the main goal of identifying the characteristics of a reliable undamaged structural model.


      PubDate: 2014-07-28T20:51:35Z
       
  • Prediction of ground motion due to the collapse of a large-scale cooling
           tower under strong earthquakes
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Feng Lin , Hongkui Ji , Yinan Li , Zhaoxia Zuo , Xianglin Gu , Yi Li
      The ground motion owing to the collapse of a large-scale cooling tower under strong earthquakes was appropriately predicted using a comprehensive approach. The predicted results can be used for the safety evaluation of nuclear-related facilities adjacent to the cooling tower as well as in the planning of nuclear power plant construction in China. In this study, a cooling tower–soil model was first developed based on a falling weight–soil model, which the authors verified by falling weight tests. Then the collapse process of a cooling tower was simulated, and the collapse-induced ground vibrations were assessed by using the proposed model. Finally, the ground motion, which was a combination of the earthquake-induced ground motion and the collapse-induced ground vibrations, was estimated based on the superposition principle of waves. It was found that the cooling tower may collapse under strong earthquakes with the peak ground accelerations (PGAs) in the range of 0.35–0.45g in x (EW) and y (NS) directions, respectively. These PGAs are far beyond the PGA range of major earthquakes in the common seismic design in China. The types of the site geologies of towers can significantly affect the collapse-induced ground vibrations. For a typical hard soil consisting of strongly weathered sandy slate, moderate ground vibrations may occur in the considered region. The collapse-induced PGAs were in the range of 0.017–0.046g for the observed points at distances of 350m in radial direction. For a rock-like foundation, the collapse-induced radial PGAs may be as high as 0.08g at distances of 350m, indicating that the effect of the collapse-induced ground vibrations on the nuclear-related facilities should be seriously assessed in certain scenarios.


      PubDate: 2014-07-28T20:51:35Z
       
  • Development of a seismic risk mitigation methodology for public buildings
           applied to the hospitals of Basilicata region (Southern Italy)
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): A. Masi , G. Santarsiero , L. Chiauzzi
      This paper deals with the development of a procedure aimed at defining a seismic risk mitigation strategy for public buildings in terms of prioritization, time required and funds. The procedure is based on a global risk index involving the entire building stock under study thus facilitating an examination of risk variation over time up to its final value. Relationships between the current seismic capacity–demand ratios and the required strengthening costs (cost models) have been developed. Each of the assumed cost models has a different target in terms of capacity–demand ratio to be obtained after strengthening, basically ranging between full retrofit and upgrading. The procedure has been applied to 69 hospital buildings located in Basilicata region for which the vulnerability data was available as a result of a large assessment program set up by the regional government. Priorities have been defined on the basis of seismic capacity, local hazard and number of human beings possibly involved (exposure). The results of different strengthening strategies have been outlined with a special focus on the pros and cons of the upgrading strategy with respect to various retrofit strategies. The procedure may be applied to different categories of public buildings by properly modifying some input parameters and partially redefining criteria for prioritization.


      PubDate: 2014-07-28T20:51:35Z
       
  • Predictive model of Arias intensity and Newmark displacement for regional
           scale evaluation of earthquake-induced landslide hazard in Greece
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Konstantinos Chousianitis , Vincenzo Del Gaudio , Ioannis Kalogeras , Athanassios Ganas
      Defining the possible scenario of earthquake-induced landslides, Arias intensity is frequently used as a shaking parameter, being considered the most suitable for characterising earthquake impact, while Newmark׳s sliding-block model is widely used to predict the performance of natural slopes during earthquake shaking. In the present study we aim at providing tools for the assessment of the hazard related to earthquake-induced landslides at regional scale, by means of new empirical equations for the prediction of Arias intensity along with an empirical estimator of coseismic landslide displacements based on Newmark׳s model. The regression data, consisting of 205 strong motion recordings relative to 98 earthquakes, were subdivided into a training dataset, used to calculate equation parameters, and a validation dataset, used to compare the prediction performance among different possible functional forms and with equations derived from previous studies carried out for other regions using global and/or regional datasets. Equations predicting Arias intensities expected in Greece at known distances from seismic sources of defined magnitude proved to provide more accurate estimates if site condition and focal mechanism influence can be taken into account. Concerning the empirical estimator of Newmark displacements, we conducted rigorous Newmark analysis on 267 one-component records yielding a dataset containing 507 Newmark displacements, with the aim of developing a regression equation that is more suitable and effective for the seismotectonic environment of Greece and could be used for regional-scale seismic landslide hazard mapping. The regression analysis showed a noticeable higher goodness of fit of the proposed relations compared to formulas derived from worldwide data, suggesting a significant improvement of the empirical relation effectiveness from the use of a regionally-specific strong-motion dataset.


      PubDate: 2014-07-28T20:51:35Z
       
  • Epistemic uncertainty in on-site earthquake early warning on the use of
           PGV–PD3 empirical models
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): J.P. Wang , Yih-Min Wu
      From the literature, we found that PGV–PD3 regressions for on-site earthquake early warning (EEW) can be quite different depending on the presumption whether or not PGV–PD3 data from different regions should be “mixable” in regression analyses. As a result, this becomes a source of epistemic uncertainty in the selection of a PGV–PD3 empirical relationship for on-site EEW. This study is aimed at examining the influence of this epistemic uncertainty on EEW decision-making, and demonstrating it with an example on the use of PGV–PD3 models developed with data from Taiwan, Japan, and Southern California. The analysis shows that using the “global” PGV–PD3 relationship for Southern California would accompany a more conservative EEW decision-making (i.e., early warning is activated more frequently) than using the local empirical model developed with the PGV–PD3 data from Southern California only. However, the influence of this epistemic uncertainty on EEW is not that obvious for the cases of Taiwan and Japan.


      PubDate: 2014-07-28T20:51:35Z
       
  • A regional near-surface high frequency spectral attenuation (kappa) model
           for northwestern Turkey
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Aysegul Askan , Fatma Nurten Sisman , Onur Pekcan
      One approach to model the high-frequency attenuation of spectral amplitudes of S-waves is to express the observed exponential decay in terms of Kappa (κ) factor [1]. Kappa is a significant parameter used for identifying the high-frequency attenuation behavior of ground motions as well as one of the key parameters for stochastic strong ground motion simulation method. As of now, there is not a systematic investigation of the Kappa parameter based on the recently-compiled Turkish ground motions. In this study, we examine a strong ground motion dataset from Northwestern Turkey with varying source properties, site classes and epicentral distances. We manually compute κ from the S-wave portion of each record and study both horizontal and vertical kappa values. We use traditional regression techniques to describe the (potential) relationships between kappa and selected independent variables such as the site class, distance from the source or magnitude of the event. A linear effect of magnitude on kappa is not found statistically significant for the database studied herein. We express the initial findings of a regional κ model for Northwestern Turkey as a function of site class and epicentral distances. Single station analyses at selected sites confirm the regional model. Finally, we present stochastic strong motion simulations of past events in the region using the proposed kappa model. Regardless of the magnitude, source-to-site distance and local site conditions at the stations, the high-frequency spectral decay is simulated effectively at all stations considered.


      PubDate: 2014-07-28T20:51:35Z
       
  • Wave propagation in semi-infinite media with topographical irregularities
           using Decoupled Equations Method
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): M.I. Khodakarami , N. Khaji
      In this paper, a novel semi-analytical method, called Decoupled Equations Method (DEM), is presented for modeling of elastic wave propagation in the semi-infinite two-dimensional (2D) media which are involved surface topography. In the DEM, only the boundaries of the problem are discretized by specific subparametric elements, in which special shape functions as well as higher-order Chebyshev mapping functions are implemented. For the shape functions, Kronecker Delta property is satisfied for displacement function. Moreover, the first derivatives of displacement function with respect to the tangential coordinates on the boundaries are assigned to zero at any given node. Employing the weighted residual method and using Clenshaw–Curtis numerical integration, coefficient matrices of the system of equations are transformed into diagonal ones, which leads to a set of decoupled partial differential equations. To evaluate the accuracy of the DEM in the solution of scattering problem of plane waves, cylindrical topographical features of arbitrary shapes are solved. The obtained results present excellent agreement with the analytical solutions and the results from other numerical methods.


      PubDate: 2014-07-28T20:51:35Z
       
  • Stochastic dynamic stiffness of a surface footing for offshore wind
           
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): M.J. Vahdatirad , L.V. Andersen , L.B. Ibsen , J.D. Sørensen
      The purpose of this study, which concerns the stochastic dynamic stiffness of foundations for large offshore wind turbines, is to quantify uncertainties related to the first natural frequency of a turbine supported by a surface footing and to estimate the low event probabilities. Herein, a simple model of a wind turbine structure with equivalent coupled springs at the base is calibrated with the mean soil property values. A semianalytical solution, based on the Green׳s function for a layered half-space is utilized for estimation of foundation responses. Soil elastic modulus and layer depth are considered as random variables with lognormal distributions. The uncertainties are quantified, and the estimation of rare events of the first natural frequency is discussed through an advanced reliability approach based on subset simulation. This analysis represents a first step in the estimation of the safety with respect to the failure of a turbine in the fatigue limit state.


      PubDate: 2014-07-28T20:51:35Z
       
  • Numerical modeling on vibroflotation soil improvement techniques using a
           densification constitutive law
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Susana López-Querol , Jaime Peco , Juana Arias-Trujillo
      The densification phenomenon in dry or completely drained sands mainly occurs when these materials are subjected to dynamic loadings. This fact induces a reduction of voids volume and consequently the compaction of the soil. The Generalized Endochronic densification law, formulated in cylindrical coordinates, has been used in a finite element model for simulating vibroflotation soil improvement techniques. The effects of vibrations at a point inside the soil mass, like those applied in vibroflotation treatment, are reproduced with this code. Absorbing boundary conditions are established at those borders where spatial domain finishes, aiming to avoid spurious, artificial reflections of stress waves, which otherwise come into the domain, disturbing the computed results. A mean densification function is defined for each spatial domain, to evaluate the effect of this technique, and also employed to optimize the distance between vibration points. This is a new rational design approach, which represents a step forward development if it is compared with the usual empirical employed procedures.


      PubDate: 2014-07-28T20:51:35Z
       
  • Scattering and diffraction of earthquake motions in irregular elastic
           layers, I: Love and SH waves
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): V.W. Lee , W.Y. Liu , M.D. Trifunac , N. Orbović
      We describe the wave propagation through an irregularly layered, elastic medium for incoming body (SH) and surface (Love) waves. As a result of irregular geometry, each layer generates additional waves by scattering and diffraction. These additional waves modify the input motions and locally may lead to larger motions and concentrations of stresses, strains, and rotations on or below the ground surface. For engineering design, and in particular for analyses of soil-structure interaction, it is important to understand the nature and the consequences of such motions. The scattering and diffraction of Love and SH waves by irregular layers will be investigated by the weighted-residuals method. The scattered and diffracted mode shapes and spectral amplification characteristics at different frequencies will be examined and discussed.


      PubDate: 2014-07-28T20:51:35Z
       
  • Liquefaction-induced deformation of earthen embankments on non-homogeneous
           soil deposits under sequential ground motions
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Manika Maharjan , Akihiro Takahashi
      Damage of embankments during earthquakes is widely attributed to the liquefaction of foundation soil. Previous studies have investigated the dynamic response of embankments by mainly considering uniform sand foundation and a single earthquake event. However, the foundation of an embankment consists of many sublayers of soil from liquefiable sand to relatively impermeable layer, and during earthquakes a mainshock may trigger numerous aftershocks within a short time which may have the potential to cause additional damage to soil structures. Accordingly, the investigation of liquefaction-induced deformation of earthen embankments on various liquefiable foundation conditions under mainshock–aftershock sequential ground motions is carried out by a series of dynamic centrifuge tests in this study. The liquefiable foundation includes uniform sand profile, continuous layered soil profile, and non-homogeneous soil profiles. Effects of various foundation conditions on embankment deformations are compared and analyzed. From the test results, it is found that the embankment resting on non-homogeneous soil deposits suffer more damage compared to the uniform sand foundation of same relative density. The test results also suggest that the sequential ground motions have a significant effect on the accumulated deformation of embankment.


      PubDate: 2014-07-28T20:51:35Z
       
  • Seismic performance of circular RC bridge columns with
           flexure–torsion interaction
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Piguang Wang , Qiang Han , Xiuli Du
      Reinforced concrete (RC) bridge columns for skewed, curved bridges and other kinds of irregular bridges can be subjected to combined loadings with axial load, shear force, flexure and torsion under multi-dimensional earthquake excitations. Combined loadings including torsion probably affect the seismic performance of these bridge columns. The experimental investigation on the seismic performance of circular RC bridge columns under combined cyclic bending and torsional loading is conducted in this paper. Twelve circular RC bridge column specimens are tested under various loading conditions: cyclic bending, cyclic torsion, and combined cyclic torsion and cyclic bending. Several combinations of cyclic bending and cyclic torsion are applied to evaluate the interaction between torsion and flexural capacity of bridge columns. The experimental results showed that the flexural capacity decreases and the damage tends to occur upward outside the flexural plastic hinge region as the level of applied cyclic torsion increases, and the torsional capacity decreases as the level of applied cyclic bending increases. The failure mode and deformation characteristics of RC bridge columns will be changed due to the effect of combined flexural and torsional loadings. The locking and unlocking effect of the spiral reinforcement on torsional and flexural envelopes of columns under pure torsion and combined cyclic bending and torsion is found. The influence of aspect ratio, longitudinal reinforcement ratio and type of spiral reinforcement on the seismic performance of columns under combined action with the same rotation-drift ratio is also discussed. An empirical flexural and torsional hysteretic model for circular RC columns with single spiral stirrup under combined cyclic bending and torsion is proposed based on the experimental results.


      PubDate: 2014-07-28T20:51:35Z
       
  • Centrifuge modeling of the seismic responses of sand deposits with an
           intra-silt layer
    • Abstract: Publication date: October 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 65
      Author(s): Chung-Jung Lee , Huei-Tsyr Chen , Hon-Chen Lien , Yu-Chen Wei , Wen-Yi Hung
      Three dynamic centrifuge model tests were conducted at an acceleration of 80g to simulate the seismic responses of level sand deposits: an intra-silt layer was embedded in two of these sand deposits at different depths. The effects of a low-permeability intra-silt layer on the build-up and dissipation of excess pore-water pressure, surface settlement, and the related liquefaction mechanism were investigated. An intra-silt layer modifies the seismic response of the sand deposit, reduces the extent of liquefaction, and thus decreases surface settlement. The depth of the intra-silt layer is one of the factors influencing the seismic responses of the sand deposits. The magnitude of the surface settlement is proportional to the degree of liquefaction in the sand deposit. The high positive hydraulic gradients appearing in both the intra-silt layer and in the sand deposit lying on the intra-silt layer can break a thinner or weaker top layer and result in sand boiling. Our visual animation of the ratio of the excess pore-water pressure and the lateral displacement revealed that the liquefaction front travels upward during shaking and the solidification front travels upward after shaking.


      PubDate: 2014-07-28T20:51:35Z
       
  • Analysis of damage data of low-rise buildings subjected to a shallow Mw6.3
           earthquake
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Bjarni Bessason , Jón Örvar Bjarnason , Ari Guðmundsson , Júlíus Sólnes , Scott Steedman
      In May 2008 a shallow Mw6.3 earthquake struck South Iceland with an epicentre close to two small towns. Nearly 5000 low-rise residential buildings were affected. The recorded maximum PGA was 0.88g. A great deal of damage occurred, but there was no loss of life. In Iceland all buildings are registered in a detailed official database and insurance against natural disasters is obligatory. As the repair costs for every affected building had to be assessed for insurance purposes this provided an unusual opportunity to review structural performance across the whole population of buildings in the affected area. The estimated repair cost was classified in a number of subcategories covering structural and non-structural damage for five different residential building typologies. Study of these buildings showed that non-structural damage dominated the overall damage. The main monetary damage was cosmetic damage of partition walls and flooring. The structural systems performed quite well and no buildings collapsed.


      PubDate: 2014-07-28T20:51:35Z
       
  • Correlation between seismic parameters of far-fault motions and damage
           indices of low-rise reinforced concrete frames
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Vui Van Cao , Hamid Reza Ronagh
      The aim of this paper is to present the results of an investigation on the degree of correlation that exists between several available seismic parameters of far-fault ground motions and the structural damage under earthquake in low-rise reinforced concrete buildings. The results show that Velocity Spectrum Intensity is the leading parameter exhibiting the strongest correlation, followed by Housner Intensity and Spectral Acceleration. Interestingly, six of the very commonly used seismic parameters demonstrate poor correlations with the damage of such structures. The results also show the existence of a very weak correlation (far behind many other seismic parameters) between the conventionally used parameter Peak Ground Acceleration and the damage (either expressed through the damage index or the inter storey drift).


      PubDate: 2014-07-28T20:51:35Z
       
  • Influence of cyclic loading history on small strain shear modulus of
           saturated clays
    • Abstract: Publication date: November 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 66
      Author(s): Chuan Gu , Jun Wang , Yuanqiang Cai , Lin Guo
      Small strain shear modulus G max is an essential parameter in soil dynamics, and it is usually estimated based on the Hardin and Richart equation. However, many previous researches on sands have indicated that the Hardin and Richart equation does not consider the influences of cyclic loading history on G max. In this paper, effects of cyclic loading history on G max of saturated clays under undrained conditions are studied using a combination device of piezoelectric-ceramic bender element system and cyclic triaxial apparatus. The dynamic pre-loading includes both relatively high amplitudes of cyclic stresses and cyclic strains. G max without cyclic loading history is also investigated for the comparison purpose. Test results show that, at the same effective stress, both cyclic strain history and cyclic stress history will induce reduction of G max compared to the corresponding G max values with non-cyclic loading effects. In strain-controlled tests, the reduction of G max is slight and relatively stable; while in stress-controlled tests, the reduction of G max increases suddenly and remarkably when the effective stresses degrade to a certain degree. The comparison between double amplitude axial strain and residual excess pore water pressure behaviors show that the remarkable reduction of G max can demonstrate the cyclic failure of saturated clays.


      PubDate: 2014-07-28T20:51:35Z
       
  • Spectral analysis of a railway track in contact with a multilayered
           poroviscoelastic soil subjected to a harmonic moving load
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Kahina Chahour , Gaëlle Lefeuve-Mesgouez , Arnaud Mesgouez
      The paper proposes an alternative approach to dispersion curves to analyse resonant phenomena in the context of wave propagation induced by a harmonic load moving over a railway track coupled to a multilayered poroviscoelastic medium. It consists of a shading representation of the spectral response in the frequency–wavenumber domain. Unlike the usual dispersion curves, it can take into account both the damping and the coupled system. Specific attention is paid to the first mode contribution. Critical ranges are determined from this shading representation: (i) for the load frequency when the load moves at a fixed constant speed, and (ii) for the load speed when the load frequency is constant. Both sub-Rayleigh and super-Rayleigh regimes are studied.


      PubDate: 2014-06-18T17:53:51Z
       
  • Modelling of raked pile foundations in liquefiable ground
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Shengzhe Wang , Rolando P. Orense
      Raked piles are believed to behave better than vertical piles in a laterally flowing liquefied ground. This paper aims at numerically simulating the response of raked pile foundations in liquefying ground through nonlinear finite element analysis. For this purpose, the OpenSees computer package was used. A range of sources have been adopted in the definition of model components whose validity is assessed against case studies presented in literature. Experimental and analytical data confirmed that the backbone force density–displacement (p–y) curve simulating lateral pile response is of acceptable credibility for both vertical and raked piles. A parametric investigation on fixed-head piles subject to lateral spreading concluded that piles exhibiting positive inclination impart lower moment demands at the head while those inclined negatively perform better at liquefaction boundaries (relative to vertical piles). Further studies reveal substantial axial demand imposed upon negatively inclined members due to the transfer of gravity and ground-induced lateral forces axially down the pile. Extra care must be taken in the design of such members in soils susceptible to lateral spreading such that compressive failure (i.e. pile buckling) is avoided.


      PubDate: 2014-06-18T17:53:51Z
       
  • Evaluation of the natural vibration frequencies of a historical masonry
           building accounting for SSI
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Francesca Ceroni , Stefania Sica , Maria Rosaria Pecce , Angelo Garofano
      The dynamic identification of a historical masonry palace located in Benevento (Italy) has been carried out. The case study is representative of many buildings located in historic Italian centres. Since the building has been instrumented by the Department of Civil Protection with a permanent dynamic monitoring system, some of the recorded data, acquired in various operating conditions have been analysed with basic instruments of the Operational Modal Analysis in order to identify the main eingenfrequencies and vibration modes of the structure. The experimental results have been compared to the numerical outcomes provided by a detailed three-dimensional Finite Element (FE) model of the building where Soil–Structure Interaction (SSI) has been taken into account. The comparison of experimental vs. numerical frequencies and vibration modes of the palace evidenced the role exerted by the subsoil on the dynamic response of the building.


      PubDate: 2014-06-18T17:53:51Z
       
  • Seismic simulation of liquefaction-induced uplift behavior of a hollow
           cylinder structure buried in shallow ground
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Gi-Chun Kang , Tetsuo Tobita , Susumu Iai
      When designing buried structures using a performance-based framework, it is important to estimate their uplift displacement. A simplified method is proposed for predicting the uplift displacement of a hollow cylinder structure buried in shallow backfill based on the equilibrium of vertical forces acting on the structure during earthquakes. However, this method only provides the maximum value, which frequently is overestimated in practical applications. To offset this limitation, first, the uplift behavior of buried hollow cylinder structures subjected to strong earthquake motions was simulated. Then, two-dimensional effective stress analyses based on the multiple shear mechanism for soil were conducted, and the results were compared with the centrifuge test data. The soil parameters were evaluated based on laboratory test results. The seismic response data from 20g centrifuge tests were analyzed, and the results were generally consistent with the results of centrifuge model tests. In particular, the effective stress model showed a reasonable ability to reproduce the varying degrees of uplift displacement depending on the geotechnical conditions of trench soils adjacent to the hollow cylinder structures buried in shallow ground.
      Graphical abstract image

      PubDate: 2014-06-18T17:53:51Z
       
  • Solution of dynamic Green׳s function for unsaturated soil under
           internal excitation
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Min Zhang , Xinghua Wang , Guangcheng Yang , Lizhao Xie
      The closed form three-dimensional Green׳s function of a semi-infinite unsaturated poroelastic medium subjected to an arbitrary internal harmonic loading is derived, with consideration of capillary pressure and dynamic shear modulus varying with saturation. By applying the Fourier expansion techniques and Hankel integral transforms to the circumferential and radial coordinates, respectively, the general solution for the governing partial differential equations is obtained in the transformed domain. A corresponding boundary value problem is formulated. The integral solutions for the induced displacements, pore pressure and net stress are then determined considering the continuity conditions. The formulas are compared with the degenerated solution of saturated soils and confirmed. Numerical results reveal that the response of the unsaturated half-space depends significantly on the saturation by altering dynamic shear modulus to account for the effects of matric suction on soil stiffness. Slight differences between the results occur if only the saturation is taken into account. Moreover, a large source-depth results in a pronounced contribution to the reduction of surface displacement amplitudes. The analytical solutions concluded in the study offer a broader application to dynamic response associated with axi-symmetric and asymmetric conditions.


      PubDate: 2014-06-18T17:53:51Z
       
  • Dynamic analysis of earth dam damaged by the 2011 Off the Pacific Coast of
           Tohoku Earthquake
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Bhuddarak Charatpangoon , Junji Kiyono , Aiko Furukawa , Chayanon Hansapinyo
      This study examines possible failure mechanisms and dynamic behavior of the Fujinuma dam, which failed following the 2011 Off the Pacific Coast of Tohoku Earthquake. The study comprises two parts: an investigation through field and laboratory experiments, and a numerical simulation of the dam. Field measurements and laboratory experiments were conducted to acquire necessary information. Microtremor observations of the surviving portion of the failed dam were performed to extract data from its dynamic characteristics. Triaxial and other laboratory tests provided information required for the analysis. For the seismic analysis, a coupled solid–fluid finite element method was applied and observed and simulated motions of the 2011 Tohoku Earthquake used as input. Mechanical behavior of the dam material was described using the Mohr–Coulomb failure criterion. Frequency and dynamic analyses were performed and dam behavior and possible failure phenomena presented. Furthermore, a comparison between the simulation results and existing facts is discussed.


      PubDate: 2014-06-18T17:53:51Z
       
  • Direct displacement loss assessment of existing RC buildings pre- and
           post-seismic retrofitting: A case study
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): D. Cardone , A. Flora
      The seismic retrofitting of a high-rise RC building, recently realized in Italy using the seismic isolation technique, is examined in terms of cost of the intervention (compared to the replacement cost of the building), seismic performances and expected benefits (compared to the building in the as-built configuration), expressed in terms of reduction of direct and indirect seismic losses in case of attainment of different limit states. In the paper, the comparison of the building performance before and after seismic retrofitting is performed in terms of Expected Annual Loss (EAL), applying a direct displacement-based loss assessment approach. The results show a considerable reduction of the EAL (approximately of 70%), passing from the as-built to the retrofitted configuration. The time needed to get the balance between costs of the intervention and benefits due to EAL reduction turns out to be of the order of 13 years.


      PubDate: 2014-06-18T17:53:51Z
       
  • Seismic stability of earth-rock dams using finite element limit analysis
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): Xin-guang Yang , Shi-chun Chi
      In this study, a finite element limit analysis method is developed to assess the seismic stability of earth-rock dams. A pseudo-static approach is employed within the limit analysis framework to determine the lower and upper bounds on the critical seismic coefficients of dams. The interlocking force in the soil is considered, and the rockfill material is assumed to follow the Mohr–Coulomb failure criterion and an associated flow rule. Based on the native form of the failure criterion, the lower and upper bound theorems are formulated as second-order cone programming problems. The nonlinear shear strength properties of rockfill materials are also considered. The developed finite element limit analysis is applied to two different types of earth-rock dams. The results indicate that the rigorous lower and upper bounds are very close even for rockfill materials with large internal friction angles. The failure surfaces are easily predicted using the contour of the yield function and the displacement field obtained by the limit analysis method. In addition, the pore water pressures are modelled as external forces in the limit analysis to assess the seismic stability of earth-rock dams in the reservoir filling stage.


      PubDate: 2014-06-18T17:53:51Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63




      PubDate: 2014-06-18T17:53:51Z
       
  • Effects of deep excavation on seismic vulnerability of existing reinforced
           concrete framed structures
    • Abstract: Publication date: September 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 64
      Author(s): P. Castaldo , M. De Iuliis
      In this paper the effects of deep excavation on seismic vulnerability of existing buildings are investigated. It is well known that deep excavations induce significant changes both in stress and strain fields of the soil around them, causing a displacement field which can modify both the static and dynamic responses of existing buildings. A FEM model of a real case study, which takes into account geometry, non-linear soil behavior, live and dead loads, boundary conditions and soil–structure interaction, has been developed in order to estimate the soil displacements and their effects on seismic behavior of a reinforced concrete framed system close to deep excavation. Considering a significant accelerometric seismic input, the non-linear dynamic responses of the reinforced concrete framed structure, both in the pre and post-excavation configurations, have been evaluated and, then, compared to estimate the modification in seismic vulnerability, by means of different seismic damage indices and inter-story drifts.


      PubDate: 2014-06-18T17:53:51Z
       
  • Unified analysis of kinematic and inertial earthquake pile responses via
           the single-input response spectrum method
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): K. Kojima , K. Fujita , I. Takewaki
      In the seismic response of a structure–pile–soil system, a kinematic response due to the forced displacement of the surface ground is important, especially in a soft ground, together with the inertial response due to the inertial forces from superstructures. In this paper it is shown that a response spectrum method in terms of complex modal quantities can be used in the evaluation of the maximum kinematic and inertial seismic responses of the structure–pile–soil system to the ground motion defined at the engineering bedrock surface as an acceleration response spectrum. The notable point is that the kinematic response, the inertial response and the total response can be evaluated by the same analysis model and method by changing the model parameters. Then it is discussed which of the simple sum or the SRSS of the kinematic and inertial responses is appropriate even in resonant cases for the evaluation of the maximum pile-head bending moment. It is concluded through many examples that the validity of the simple sum or the SRSS depends on the relation between the fundamental natural period of the surface ground and that of the superstructure while an averaged evaluation is valid in resonant cases.


      PubDate: 2014-04-29T18:55:28Z
       
  • Dynamic analysis of offshore wind turbine in clay considering
           soil–monopile–tower interaction
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Swagata Bisoi , Sumanta Haldar
      A comprehensive study is performed on the dynamic behavior of offshore wind turbine (OWT) structure supported on monopile foundation in clay. The system is modeled using a beam on nonlinear Winkler foundation model. Soil resistance is modeled using American Petroleum Institute based cyclic p–y and t–z curves. Dynamic analysis is carried out in time domain using finite element method considering wind and wave loads. Several parameters, such as soil–monopile–tower interaction, rotor and wave frequencies, wind and wave loading parameters, and length, diameter and thickness of monopile affecting the dynamic characteristics of OWT system and the responses are investigated. The study shows soil–monopile–tower interaction increases response of tower and monopile. Soil nonlinearity increases the system response at higher wind speed. Rotor frequency is found to have dominant role than blade passing frequency and wave frequency. Magnitude of wave load is important for design rather than resonance from wave frequency.


      PubDate: 2014-04-29T18:55:28Z
       
  • Permanent deformation estimates of dynamic equipment foundations:
           Application to a gas turbine in granular soils
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Rubén Galindo , Manuel Illueca , Rafael Jimenez
      Permanent displacements of a gas turbine founded on a fine, poorly graded, and medium density sand are studied. The amplitudes and modes of vibration are computed using Barkan´s formulation, and the “High-Cycle Accumulation” (HCA) model is employed to account for accumulated deformations due to the high number of cycles. The methodology is simple: it can be easily incorporated into standard mathematical software, and HCA model parameters can be estimated based on granulometry and index properties. Special attention is devoted to ‘transient’ situations at equipment´s start-up, during which a range of frequencies – including frequencies that could be similar to the natural frequencies of the ground – is traversed. Results show that such transient situations could be more restrictive than stationary situations corresponding to normal operation. Therefore, checking the stationary situation only might not be enough, and studying the influence of transient situations on computed permanent displacements is needed to produce a proper foundation design.


      PubDate: 2014-04-29T18:55:28Z
       
 
 
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