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  Subjects -> EARTH SCIENCES (Total: 586 journals)
    - EARTH SCIENCES (433 journals)
    - GEOLOGY (65 journals)
    - GEOPHYSICS (27 journals)
    - HYDROLOGY (17 journals)
    - OCEANOGRAPHY (44 journals)

EARTH SCIENCES (433 journals)            First | 1 2 3 4 5     

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: 163)
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: 140)
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)
Pesquisas em Geociências     Open Access   (Followers: 1)
Petroleum Geoscience     Hybrid Journal   (Followers: 5)
Petrology     Hybrid Journal   (Followers: 6)
Photogrammetrie - Fernerkundung - Geoinformation     Full-text available via subscription  
Physical Geography     Hybrid Journal   (Followers: 5)
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 7)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 6)
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: 7)
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)
Quaternary Science Reviews     Hybrid Journal   (Followers: 10)
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: 1)
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)
Stratigraphy and Geological Correlation     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]
  • 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
       
  • Corrigendum to “Nonlinear rocking stiffness of foundations”
           [Soil Dyn. Earthq. Eng. 47 (2013) 83–91]
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): G. Gazetas , I. Anastasopoulos , O. Adamidis , Th. Kontoroupi



      PubDate: 2014-06-18T17:53:51Z
       
  • A GIS procedure for fast topographic characterization of seismic recording
           stations
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Vera Pessina , Emilia Fiorini
      Morphometric analyses of high resolution digital elevation models (DEM), with the support of Geographic Information Systems (GIS), have been implemented to provide a practical tool for the identification on a large scale of sites where, according to the EC8 prescriptions, a topography amplification is expected. An ad hoc procedure for the hilltop ridge detection was implemented to be used in the morphological characterization, together with the standard GIS sequence of steps. The proposed method allowed the fast classification of more than 800 seismic recording stations located on the Alps and the Apennine, according to the indications of the current European norm and the Italian seismic code. The aim is to improve the characterization of the stations of seismic archives, in the view of a potential cross-checking of observed amplification with the attributed site class category.
      Graphical abstract image

      PubDate: 2014-06-18T17:53:51Z
       
  • Site characterizations for the Tehran network (TDMMO) in Tehran Region
           Using Micro-Earthquake, Microtremor and Quarry Blast Data
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Jamileh Vasheghani Farahani , Mehdi Zaré
      We did a Study of Horizontal-to-Vertical Component Spectral Ratio in the Tehran seismic zone. Micro-earthquakes, microtremors and quarry blasts data were used as an estimation of the site response in the Tehran zone. Site effects were studied based on horizontal to vertical ratios by the Nakamura׳s technique. Also, we used the spectra of signals for three components with the lowest noise levels for spectral slope studies. The analysis used seismic events from a network of 13 seismic stations by the permanent local seismological network of the Tehran Disaster Mitigation and Management Organization (TDMMO) from 2004 to 2007. The number of events used were different for each station. Quarry blast events were with 1.2≤M L ≤2.2 and micro-earthquakes were with 1.1≤M L ≤4.1. By comparing results for earthquake, microtremor and quarry blast, we could see that there is a significant difference between them. The data showed clear observations, especially in high-frequencies. The H/V spectral ratios indicate dominant frequency for rock/soft site with a higher ratio level for quarry blast ratios, which are comparable to the earthquake results due to their difference sources. The results derived by spectral H/V ratios and spectral analysis may be used to distinguish between local earthquakes and quarry blasts.


      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
       
  • A procedure for simulating synthetic accelerograms compatible with
           correlated and conditional probabilistic response spectra
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Irmela Zentner
      The modeling of seismic load is a major topic that has to be addressed thoroughly in the framework of performance based seismic analysis and design. In this paper, a simple procedure for simulating artificial earthquake accelerograms matching the statistical distribution of response spectra, as given by median ground motion prediction equations, the standard deviation and correlation coefficients, is proposed. The approach follows the general ideas of the (natural) ground motion selection algorithms proposed by Baker [4] and Wang [43] but using simulated (artificial) “spectrum-compatible” accelerograms. This allows to simulate spectrum-compatible accelerograms featuring variability similar to the one of recorded accelerograms when the match of median and ±1 standard-deviation response spectra is imposed by the regulator. The procedure is illustrated by an application to the NGA ground motion data and models.


      PubDate: 2014-06-18T17:53:51Z
       
  • Dynamic analysis of flexible cantilever wall retaining elastic soil by a
           modified Vlasov–Leontiev model
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Qijian Liu , Yuxiang Tian , Fangjun Deng
      Dynamic response of a flexible cantilever wall retaining elastic soil to harmonic transverse seismic excitations is determined with the aid of a modified Vlasov–Leontiev foundation model and on the assumption of vanishing vertical displacement of the soil medium. The soil–wall interaction is taken into consideration in the presented model. The governing equations and boundary conditions of the two unknown coupled functions in the model are derived in terms of Hamilton׳s principle. Solutions of the two unknown functions are obtained on the basis of an iterative algorithm. The present method is verified by comparing its results with those of the existing analytical solution. Moreover, a mechanical model is proposed to evaluate the presented method physically. A parametric study is performed to investigate the effects of the soil–wall system properties and the excitations on the dynamic response of the wall.


      PubDate: 2014-06-18T17:53:51Z
       
  • A practical method for utilization of commercial cyclic testing
           apparatuses for computation of site response in central Adapazari
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Mustafa Tolga Yılmaz , Kaveh Hassan Zehtab
      We suggest a practical method for estimating strain–modulus–damping relationships for utilization in equivalent-linear site response analyses, so that the necessity for more sophisticated sampling and testing procedures can be justified. The method employs the commercial cyclic testing apparatuses, which have limitations in low-strain ranges, and the in-situ seismic tests. The shear modulus at about 1% cyclic shear strain amplitude and the shear-wave velocity measured in-situ is used for building a hyperbolic relationship between shear stress and shear strain. An extension of Masing׳s rule and the constraint on hysteretic damping at 1% cyclic shear strain amplitude leads to a strain–damping relationship. By putting a particular emphasis on the soils of Adapazarı, a city famous for the concentrated damage on alluvium basin during the 1999 Kocaeli (Mw7.4) earthquake, we demonstrated the usefulness of the method, and concluded that the shear-modulus reduction and damping characteristics of Adapazarı soils can yield to site amplification factors greater than those predicted by strain–modulus–damping relationships presented in literature, and can more efficiently explain the concentration of damage on the alluvium basin. Through the comparisons of spectral amplification factors computed by equivalent-linear site response analyses, we justified the necessity to run a more sophisticated testing program on determination of cyclic stress–strain behavior of Adapazarı soils, and consequently to consider transient nonlinear site-response analyses in order to reduce the possible bias in calculation of spectral amplification factors.


      PubDate: 2014-06-18T17:53:51Z
       
  • A unified approach for long-term behavior and seismic response of
           AAR-affected concrete dams
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Jianwen Pan , Yanjie Xu , Feng Jin , Chuhan Zhang
      Concrete dams suffering from alkali-aggregate reaction (AAR) exhibit swelling and deterioration of concrete or even cracking over a long period. The deterioration of concrete may significantly affect the dynamic behavior of the structures, and it is necessary to estimate seismic safety of the deteriorated dams subjected to strong earthquakes. A unified approach is presented in this paper for long-term behavior and seismic response analysis of AAR-affected concrete dams by combining AAR kinetics, effects of creep and plastic-damage model in the finite element method. The proposed method is applied to a gravity dam and an arch dam. The long-term behavior of the AAR-affected dams is first predicted in terms of anisotropic swelling, spatially non-uniform deterioration of concrete, and cracking initiation and propagation with the development of AAR. The seismic response of the deteriorated dams is subsequently analyzed based on the state of the structures at the end of the long-term analysis. The AAR-induced expansion displacements obtained from the proposed method are in good agreement with the measured ones in the long-term operation. The simulated cracking patterns in the dams caused by the continuing AAR are also similar to the field observation. The results from the seismic analysis show that AAR-induced deterioration of concrete and cracking may lead to more severe damage cracking in the dams during earthquake. The dynamic displacements are also increased compared with the dams that are not suffering from AAR. The seismic safety of the AAR-affected concrete dams is significantly reduced because of the AAR-induced deterioration of concrete and cracking.


      PubDate: 2014-06-18T17:53:51Z
       
  • Dynamic analysis of a rigid circular foundation on a transversely
           isotropic half-space under a buried inclined time-harmonic load
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): M. Eskandari , S.F. Ahmadi , S. Khazaeli
      The dynamic analysis of a surface rigid foundation in smooth contact with a transversely isotropic half-space under a buried inclined time-harmonic load is addressed. By virtue of the superposition technique, appropriate Green׳s functions, and employing further mathematical techniques, solution of the mixed-boundary-value problem is expressed in terms of two well-known Fredholm integral equations. Two limiting cases of the problem corresponding to the static loading and isotropic medium are considered and the available results in the literature are fully recovered. For the static case, the results pertinent to both frictionless and bonded contacts are obtained and compared. With the aid of the residue theorem and asymptotic decomposition method, an effective and robust approach is proposed for the numerical evaluation of the obtained semi-infinite integrals. For a wide range of the excitation frequency, both normal and rotational compliances are depicted in dimensionless plots for different transversely isotropic materials. Based on the obtained results, the effects of anisotropy are highlighted and discussed.


      PubDate: 2014-06-18T17:53:51Z
       
  • Curvature ductility of columns and structural displacement ductility in RC
           frame structures subjected to ground motions
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Jing Zhou , Fangping He , Tian Liu
      This paper examined the statistical relationship between the curvature ductility demands of columns and the global displacement ductility demands of reinforced concrete (RC) frame structures when subjected to earthquakes. Elements with a designated moment–curvature relationship were adopted for both beam and column elements, and five-story and ten-story RC frame numerical structures were established. Using pushover analysis and earthquake nonlinear dynamic time-history analysis, the maximum global displacement ductility demands of the structure and the maximum curvature ductility demands of the columns were determined. The effects of the spectral acceleration and the strong column factor on ductility demands were analyzed, and the quantitative relationship between the curvature ductility demands of columns and the global displacement ductility demands of frame structures were established. Moreover, the validity of the established relationship was further tested and verified through a real-world application. The results show that the maximum curvature ductility demands of the columns and the maximum displacement ductility demands of the structure were positively associated with the spectral acceleration and negatively associated with the strong column factor. A proposed first-degree linear relationship between curvature ductility of columns and structural displacement ductility in RC frame structures with two parameters was obtained by curve fitting, while considering the effect of the strong column factor. The model was highly correlated with the sampling analysis data. Applying the empirical model established in this study is a simple and effective means to guide the design of ductility and the assessment of RC frame columns.


      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
       
  • A note on three-dimensional scattering and diffraction by a hemispherical
           canyon–I: Vertically incident plane P-wave
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Vincent W. Lee , Guanying Zhu
      The three-dimensional scattering by a hemi-spherical canyon in an elastic half-space subjected to seismic plane and spherical waves has long been a challenging boundary-value problem. It has been studied by earthquake engineers and strong-motion seismologists to understand the amplification effects caused by surface topography. The scattered and diffracted waves will, in all cases, consist of both longitudinal (P-) and shear (S-) shear waves. Together, at the half-space surface, these waves are not orthogonal over the infinite plane boundary of the half-space. Thus, to simultaneously satisfy both zero normal and shear stresses on the plane boundary numerical approximation of the geometry and/or wave functions were required, or in some cases, relaxed (disregarded). This paper re-examines this boundary-value problem from the applied mathematics point of view, and aims to redefine the proper form of the orthogonal spherical-wave functions for both the longitudinal and shear waves, so that they can together simultaneously satisfy the zero-stress boundary conditions at the half-space surface. With the zero-stress boundary conditions satisfied at the half-space surface, the most difficult part of the problem will be solved, and the remaining boundary conditions at the finite canyon surface will be easy to satisfy.


      PubDate: 2014-04-29T18:55:28Z
       
  • Full-scale experimental modal analysis of an arch dam: The first
           experience in Iran
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Reza Tarinejad , Mohammad T. Ahmadi , Ronald S. Harichandran
      Forced vibration field tests and finite-element studies were conducted on the Shahid Rajaee concrete arch dam in Northern Iran to determine the dynamic properties of the dam–reservoir–foundation system. The first forced vibration tests on the dam were performed with two different types of exciter units, with a limited maximum force, bolted on the dam crest for alternative in-phase and out-of-phase sequencing. Because of an insufficient number of recording sensors, two arrangements of sensors were used to cover sufficient points on the dam crest and one gallery during tests. Two kinds of vibration tests, on–off and frequency sweeping, were carried out on the dam. The primary natural frequencies of the coupled system for both symmetric and anti-symmetric vibration modes were approximated during on–off tests in two types of sequencing of exciters, in phase and out-of-phase, with a maximum frequency of 14Hz. The principal forced vibration tests were performed at precise resonant frequencies based on the results of the on–off tests in which sweeping around the approximated frequencies at 0.1Hz increments was performed. Baseline correction and suitable bandpass filtering were applied to the test records and then signal processing was carried out to compute the auto power, cross power and coherence spectra. Nine middle modes of vibration of the coupled system and corresponding damping ratios were estimated. The empirical results are compared against the results from calibrated finite-element modeling of the system using former ambient vibration tests, considering the dam–reservoir–foundation interaction effects. Good agreement is obtained between experimental and numerical results for eight middle modes of the dam–reservoir–foundation system.


      PubDate: 2014-04-29T18:55:28Z
       
  • Convergence analyses of different modeling schemes for generalized
           Lippmann–Schwinger integral equation in piecewise heterogeneous
           media
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Geng-Xin Yu , Li-Yun Fu
      For wave propagation simulation in piecewise heterogeneous media, Gaussian-elimination-based full-waveform solutions to the generalized Lippmann–Schwinger integral equation (GLSIE) are highly accurate, but involved with extremely time-consuming computations because of the very large size of the resulting boundary–volume integral equation matrix to be inverted. Several flexible approximations to the GLSIE are scaled in an iterative way to adapt numerical solutions to the smoothness of heterogeneous media in terms of incident wavelengths, with a great saving of computing time and memory. Among various typical iterative schemes to the GLSIE matrix, the generalized minimal residual method (GMRES) is an efficient approach to reduce the computational intensity to some degree. The most efficient approximation can be obtained using a Born series, as an alternative iterative solution, to both the boundary-scattering and volume-scattering waves, leading to the Born-series approximation (BSA) scheme and the improved Born-series approximation (IBSA) scheme. These iteration schemes are validated by dimensionless frequency responses to a heterogeneous semicircular alluvial valley, and then applied to a heterogeneous multilayered model by calculating synthetic seismograms to evaluate approximation accuracies. Numerical experiments, compared with the full-waveform numerical solution, indicate that the convergence rates of these methods decrease gradually with increasing velocity perturbations. The comparison also shows that the BSA scheme has a faster convergence than the GMRES method for velocity perturbations less than 10 percent, but converges slowly and even hardly achieves convergence for velocity perturbations greater than 15 percent. The IBSA scheme gives a superior performance over the other methods, with the least iterations to achieve the necessary convergence.


      PubDate: 2014-04-29T18:55:28Z
       
  • Seismic base-isolation mechanism in liquefied sand in terms of energy
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Takaji Kokusho
      Seismic base isolation effect in a liquefied sand layer was investigated based on soil properties measured in a series of undrained cyclic triaxial tests. Transmission of seismic wave in a soil model consisting of a liquefied surface layer and an underlying nonliquefied layer was analyzed in terms of energy, considering liquefaction-induced changes in S-wave velocity and internal damping. It was found that, between two different base-isolation mechanisms, a drastic increase in wave attenuation in the liquefied layer due to shortening wave length gives a greater impact on the base isolation with increasing thickness of the liquefied layer than the change of seismic impedance between the liquefied and nonliquefied layer. Also indicated was that cyclic mobility behavior in dilative clean sand tends to decrease the seismic isolation effect to a certain extent.


      PubDate: 2014-04-29T18:55:28Z
       
  • Simulating stiffness degradation and damping in soils via a simple
           visco-elastic–plastic model
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Federico Pisanò , Boris Jeremić
      Stiffness degradation and damping represent some of the most well-known aspects of cyclic soil behavior. While standard equivalent linear approaches reproduce these features by (separately) prescribing stiffness reduction and damping curves, in this paper a multiaxial, 3D, viscoelastic – plastic model is developed for the simultaneous simulation of both cyclic curves over a wide cyclic shear strain range. The proposed constitutive relationship is based on two parallel resisting/dissipative mechanisms, purely frictional (elastic–plastic) and viscous. The frictional mechanism is formulated as a bounding surface plasticity model with vanishing elastic domain, including pressure-sensitive failure locus and non-associative plastic flow – which are essential for effective stress analysis. At the same time, the use of the parallel viscous mechanism is shown to be especially beneficial to improve the simulation of the overall dissipative performance. In order to enable model calibration from stiffness degradation ( G / G max ) and damping curves, the constitutive equations are purposely kept as simple as possible with a low number of material parameters. Although the model performance is here explored with reference to pure shear cyclic tests, the 3D, multiaxial formulation is appropriate for general loading conditions.


      PubDate: 2014-04-29T18:55:28Z
       
  • Rocking instability of free-standing statues atop slender viscoelastic
           columns under ground motion
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Anthony Kounadis
      The highly complex rocking response of free-standing statues atop multi-drum columns underground excitation resulting in insuperable difficulties for obtaining reliable solution is reexamined analytically. This is achieved after simulating the columns by monolithic viscoelastic cantilevers having structural damping, based on experiments, equivalent to the energy dissipation due to impact and sliding of multi-drum columns. Subsequently, the conditions of rocking (overturning) instability of free-standing rigid blocks (representing the statues) after their uplift from the top surface of the laterally vibrating cantilevers, are established, including overturning with or without impact. Attention focuses on the minimum amplitude ground acceleration which leads to an escaped motion through the vanishing of the angular velocity and acceleration. Maximization of such a minimum amplitude (implying stabilization) of the rigid block is obtained by seeking the optimum combination of values of the slenderness ratio of the column and its height. Analytically derived results based on linearised analyses are in excellent agreement with those obtained via nonlinear numerical analyses.


      PubDate: 2014-04-29T18:55:28Z
       
  • Simulation of soil–foundation–structure interaction of Hualien
           large-scale seismic test using dynamic centrifuge test
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Jeong Gon Ha , Sei-Hyun Lee , Dong-Soo Kim , Yun Wook Choo
      Understanding the soil–structure interaction (SSI) mechanism is crucial in the seismic design of nuclear power plant (NPP) containment systems. Although the numerical analysis method is generally used in seismic design, there is a need for experimental verification for the reliable estimation of SSI behavior. In this study a dynamic centrifuge test was performed to simulate the SSI behavior of a Hualien large-scale seismic test (LSST) during the Chi-Chi earthquake. To simulate the soil profile and dynamic soil properties of the Hualien site, a series of resonant column (RC) tests was performed to determine the model soil preparation conditions, such as the compaction density and the ratio of soil–gravel contents. The variations in the shear wave velocity (V S) profiles of the sand, gravel, and backfill layers in the model were estimated using the RC test results. During the centrifuge test, the V S profiles of the model were evaluated using in-flight bender element tests and compared with the in-situ V S profile at Hualien. The containment building model was modeled using aluminum and the proper scaling laws. A series of dynamic centrifuge tests was performed with a 1/50 scale model using the base motion recorded during the Chi-Chi-earthquake. In the soil layer and foundation level, the centrifuge test results were similar to the LSST data in both the time and frequency domains, but there were differences in the structure owing to the complex structural response as well as the material damping difference between the concrete in the prototype and aluminum in the model. In addition, as the input base motion amplitude was increased to a maximum value of 0.4g (prototype scale), the responses of the soil and containment model were measured. This study shows the potential of utilizing dynamic centrifuge tests as an experimental modeling tool for site specific SSI analyses of soil–foundation–NPP containment system.


      PubDate: 2014-04-29T18:55:28Z
       
  • Cyclic response of saturated silts
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Selman Sağlam , B.Sadık Bakır
      Softening and strength loss of sands with increasing excess pore water pressure under repeated loads is well-known. However, extensive damage to the built environment also occurs at the sites underlain by fine grained soils during seismic shaking. The primary objective of this study is to investigate the factors affecting cyclic behavior of saturated low-plastic silt through laboratory testing. For this purpose, an extensive laboratory testing program including conventional monotonic and cyclic triaxial tests was carried out over reconstituted silt samples. The effects of the inherent soil properties and the effects of loading characteristics on the cyclic response of saturated low-plastic reconstituted silt samples were examined separately. Based on the test results, a model was introduced to estimate the effect of initial shear stress on the cyclic response. Besides, liquefaction susceptibility of the samples was examined via current liquefaction susceptibility criteria.


      PubDate: 2014-04-29T18:55:28Z
       
  • Large-scale shaking table model tests of aseismic measures for concrete
           faced rock-fill dams
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Jun Liu , Fuhai Liu , Xianjing Kong , Long Yu
      The aseismic design of concrete faced rock-fill dams (CFRDs) has become vitally important in recent years. A series of 1-g large-scale shaking table model tests were conducted, applying similitude laws to evaluate the effectiveness of various aseismic measures. The following four reinforcing measures are discussed in this study: reinforcing the top zone with geogrid, protecting the downstream slope surface using stone block, replacing the top zone of the dam with cemented rock-fill material or concrete layers. The failure developments were visualised using the particle image velocimetry (PIV) technique. The mechanisms of these reinforcement measures were analysed in detail. The effectiveness of these measures was evaluated by comparing the crest settlement rates and key accelerations corresponding to surface grain yield, slab fracture and slab dislocation. Based on the model test results, a combination of reinforcement measures was proposed for the prototype CFRDs.


      PubDate: 2014-04-29T18:55:28Z
       
  • Generalized cyclic p–y curve modeling for analysis of laterally
           loaded piles
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Mehdi Heidari , Hesham El Naggar , Mojtaba Jahanandish , Arsalan Ghahramani
      Owing to their simplicity and reasonable accuracy, Beam on Nonlinear Winkler Foundation (BNWF) models are widely used for the analysis of laterally loaded piles. Their main drawback is idealizing the soil continuum with discrete uncoupled springs representing the soil reactions to pile movement. Static p–y curves, obtained from limited full-scaled field tests, are generally used as a backbone curve of the model. However, these empirically derived p–y curves could not incorporate the effects of various pile properties and soil continuity. The strain wedge method (SWM) has been improved to assess the nonlinear p–y curve response of laterally loaded piles based on a three-dimensional soil–pile interaction through a passive wedge developed in front of the pile. In this paper, the SWM based p–y curve is implemented as the backbone curves of developed BNWF model to study the nonlinear response of single pile under cyclic lateral loading. The developed nonlinear model is capable of accounting for various important soil–pile interaction response features such as soil and pile yielding, cyclic degradation of soil stiffness and strength under generalized loading, soil–pile gap formation with soil cave-in and recompression, and energy dissipation. Some experimental tests are studied to verify the BNWF model and examine the effect of each factor on the response of laterally loaded pile embedded in sand and clay. The experimental data and computed results agree well, confirming the model ability to predict the response of piles under one-way and two-way cyclic loading. The results show that the developed model can satisfactorily simulate the pile stiffness hardening due to soil cave in and sand densification as observed in the experiment. It is also concluded from the results that the gap formation and soil degradation have significant effects on the increase of lateral pile-head deflection and maximum bending moment of the pile in cohesive soils.


      PubDate: 2014-04-29T18:55:28Z
       
  • The dynamic response of fluid-saturated porous materials with application
           to seismically induced soil liquefaction
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Y. Heider , O. Avci , B. Markert , W. Ehlers
      The numerical simulation of liquefaction phenomena in fluid-saturated porous materials within a continuum-mechanical framework is the aim of this contribution. This is achieved by exploiting the Theory of Porous Media (TPM) together with thermodynamically consistent elasto-viscoplastic constitutive laws. Additionally, the Finite Element Method (FEM) besides monolithic time-stepping schemes is used for the numerical treatment of the arising coupled multi-field problem. Within an isothermal and geometrically linear framework, the focus is on fully saturated biphasic materials with incompressible and immiscible phases. Thus, one is concerned with the class of volumetrically coupled problems involving a potentially strong coupling of the solid and fluid momentum balance equations and the algebraic incompressibility constraint. Applying the suggested material model, two important liquefaction-related incidents in porous media dynamics, namely the flow liquefaction and the cyclic mobility, are addressed, and a seismic soil–structure interaction problem to reveal the aforementioned two behaviors in saturated soils is introduced.


      PubDate: 2014-04-29T18:55:28Z
       
  • Predicting onset of cyclic instability of loose sand with fines using
           instability curves
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): M.A.L. Baki , M.M. Rahman , S.R. Lo
      This study utilises the equivalent granular state parameter, ψ ⁎, as a key parameter for studying static and cyclic instability and their linkage. ψ ⁎ can be considered as a generalisation of the state parameter as first proposed by Been and Jefferies so that the influence of fines content in addition to stress and density state can be captured. Test results presented in this study conclusively showed that ψ ⁎ at the start of undrained shearing and η IS, the stress ratio at onset of static instability, can be described by a single relationship irrespective of fines content for both compression and extension shearing. This single relationship is referred as instability curve. However, the instability curve in extension shearing is different from that of compression. In this paper, the capacity of the instability curve in predicting triggering of cyclic instability was evaluated experimentally. An extensive series of undrained one-way (compression) and non-symmetric two-way cyclic triaxial tests, in addition to monotonic triaxial tests in both compression and extension were conducted for this evaluation. Furthermore, a published database for Hokksund sand with fines was also used. Test results show that cyclic instability was triggered shortly after the cyclic effective stress path crossed the estimated η IS-zone(s) as obtained from instability curve(s) irrespective of whether instability occurs in the compression or extension side.


      PubDate: 2014-04-29T18:55:28Z
       
  • Damping coefficients for soil–structure systems and evaluation of
           FEMA 440 subjected to pulse-like near-fault earthquakes
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Faramarz Khoshnoudian , Ehsan Ahmadi , Ali Imani Azad
      In this study, attempts are made to investigate the effects of inertial soil–structure interaction (SSI) on damping coefficients subjected to pulse-like near-fault ground motions. To this end, a suit of 91 pulse-like near-fault ground motions is adopted. The soil and superstructure are idealized employing cone model and single-degree-of-freedom (SDOF) oscillator, respectively. The results demonstrate that soil flexibility reduces and amplifies the damping coefficients for structural viscous damping levels higher and lower than 5%, respectively. The coefficients reach one for both acceleration and displacement responses in cases of dominant SSI effects. The effect of structure dimensions on damping confidents are found insignificant. Moreover, damping coefficients of displacement responses are higher than those of acceleration responses for both fixed-base and flexible-base systems. Evaluation of damping correction factor introduced by FEMA 440 shows its inefficiency to predict acceleration response of soil–structure systems under pulse-like near-fault ground motions. Soil flexibility makes the damping correction factor of moderate earthquakes more pronounced and a distinctive peak value is reported for cases with dominant SSI effects.


      PubDate: 2014-04-29T18:55:28Z
       
  • Ground motion modeling for site effects at L’Aquila and middle
           Aterno river valley (central Italy) for the MW 6.3, 2009 earthquake
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): C. Nunziata , M.R. Costanzo
      Ground motion for the 6 April 2009 (M w 6.3) earthquake is computed along 2-D cross-sections at L’Aquila by a hybrid method (modal summation plus finite differences) and validated with recordings at AQU, AQK, AQG, AQA and AQV stations. Parametric studies of S-wave velocities of the shallowest lithotypes allow to get a general agreement between synthetic and observed response spectra, despite the scaled point-source approach and the lack of detailed geological and seismic studies. It results that the megabreccia covering on lacustrine soils, characterizing the historical center of L’Aquila, is responsible of spectral amplifications along the vertical (2–7) and horizontal components (2–3) at a wide frequency range (0.6–7Hz). The covering of alluvial soils in the middle Aterno river valley is responsible of amplifications at 2–7Hz both in the horizontal and vertical planes of the motion. Such amplifications evidence that site effects might have been responsible of structural damages.


      PubDate: 2014-04-29T18:55:28Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62




      PubDate: 2014-04-29T18:55:28Z
       
  • Seismic response of multi-tiered reinforced soil retaining walls
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Huabei Liu , Guangqing Yang , Hoe I. Ling
      In this study, a validated Finite Element procedure was used to investigate the similarities and differences of seismic performances between single- and multi-tiered reinforced soil walls. Three-tiered walls at a total height of 9m were analyzed together with vertical walls at the same height. It was found from the Finite Element analyses that the resonant frequency of reinforced soil walls might increase with an increase in the tier-offset. The multi-tiered configuration could considerably reduce the residual lateral facing displacement and the average reinforcement load, and the reinforcement load distribution with height was different from that in vertical walls. With the same reinforcement length and spacing, the multi-tiered walls resulted in smaller reinforcement connection loads with the facing blocks. The study filled the gap of seismic behavior of multi-tiered reinforced soil retaining walls and revealed a few unique dynamic properties of this type of earth structures.


      PubDate: 2014-04-29T18:55:28Z
       
  • Small-strain dynamic characterization of clayey soil from the Texcoco
           Lake, Mexico
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Mario Flores-Guzmán , Efraín Ovando-Shelley , Celestino Valle-Molina
      The area occupied by the former Texcoco Lake was part of a system of lakes inside the Basin of Mexico. The subsoil there has been studied in the past but there is still a need for more and more thorough investigations into the dynamic properties of its highly compressible clays. This paper describes the results of an experimental laboratory research in which a triaxial cell fitted with bender elements was used to measure shear wave velocities (V s ) in clay specimens from the former Texcoco Lake. Soil specimens were subjected to isotropic loading–unloading cycles and values of V s were determined during the saturation stage and after each stress increment or decrement. Our results show that irrespective of the testing method, shear waves velocities differ in no more than 7–15%.


      PubDate: 2014-04-29T18:55:28Z
       
  • The extended consecutive modal pushover procedure for estimating the
           seismic demands of two-way unsymmetric-plan tall buildings under influence
           of two horizontal components of ground motions
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Mehdi Poursha , Faramarz Khoshnoudian , A.S. Moghadam
      This paper aims to extend the consecutive modal pushover (CMP) procedure for estimating the seismic demands of two-way unsymmetric-plan tall buildings subjected to bi-directional seismic ground motions taking the effects of higher modes and torsion into account. Multi-stage and single-stage pushover analyses are carried out in both X and Y directions. Inelastic seismic responses obtained by multi-stage and single-stage pushover analyses for X and Y directions are combined using the SRSS combination scheme. The final seismic responses are determined by enveloping the combined results of multi-stage and single-stage pushover analyses. To evaluate the accuracy of the proposed procedure, it is applied to two-way unsymmetric-plan tall buildings which include torsionally stiff and torsionally flexible systems. The results derived from the CMP procedure are compared with those from nonlinear response history analysis (NL-RHA), as a benchmark solution. Moreover, the advantages of the proposed procedure are demonstrated by comparing the results derived from the CMP to those from pushover analysis with uniform and fundamental effective mode distributions. The proposed procedure is able to accurately predict amplification or de-amplification of the seismic displacements at the flexible and stiff edges of the two-way unsymmetric-plan tall buildings by considering the effects of higher modes and torsion. The extended CMP procedure can accurately estimate the peak inelastic responses, such as displacements and storey drifts. The CMP procedure features a higher potential in estimating plastic hinge rotations at both flexible and stiff sides of unsymmetric-plan tall buildings under bi-directional seismic excitation when compared to the uniform and fundamental effective mode force distributions.


      PubDate: 2014-04-29T18:55:28Z
       
  • Site-specific and spatially-distributed ground-motion intensity estimation
           in the 2010–2011 Canterbury earthquakes
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Brendon A. Bradley
      This paper presents site-specific and spatially-distributed ground-motion intensity estimates which have been utilized in the aftermath of the 2010–2011 Canterbury, New Zealand earthquakes. The methodology underpinning the ground motion intensity estimation makes use of both prediction models for ground motion intensity and its within-event spatial correlation. A key benefit of the methodology is that the estimated ground motion intensity at a given location is not a single value but a distribution of values. The distribution is comprised of both a mean and standard deviation, with the standard deviation being a function of the distance to nearby observations at strong motion stations. The methodology is illustrated for two applications. Firstly, maps of conditional peak ground acceleration (PGA) have been developed for the major events in the Canterbury earthquake sequence, which among other things, have been utilized for assessing liquefaction triggering susceptibility of land in residential areas. Secondly, the conditional distribution of response spectral ordinates is obtained at the location of the Canterbury Television building (CTV), which catastrophically collapsed in the 22 February 2011 earthquake. The conditional response spectra provide insight for the selection of ground motion records for use in forensic seismic response analyses of important structures at locations where direct recordings are absent.


      PubDate: 2014-04-29T18:55:28Z
       
  • Two-dimensional earthquake vibrations in sedimentary basins – SH
           waves
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Hasan Faik Kara , Mihailo D. Trifunac
      In this paper, long- and short-period vibrations in sedimentary basins are studied. First, two-dimensional, long-period vibrations of deep semi-circular basins for excitation by earthquake faults, which can be inside or outside the basin, are analyzed. Second, recurring intermediate peak frequencies of Fourier-spectrum amplitudes of recorded accelerations along the east–west axis of the San Fernando Valley during the 1994 Northridge, California earthquake are reviewed. It is shown that these intermediate frequencies cannot be associated with vibrations of the entire San Fernando basin because the frequency range of typical strong-motion recordings (0.04 to 15.0s) is too narrow to include the long-period vibration of the whole basin. These intermediate vibrations are consistent with Kanai׳s one-dimensional models consisting of parallel layers and excited by vertically incident shear waves.


      PubDate: 2014-04-29T18:55:28Z
       
  • Effect of seismic sequences in reinforced concrete frame buildings located
           in soft-soil sites
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Jorge Ruiz-García , Marco V. Marín , Amador Terán-Gilmore
      On September 19 and 20, 1985, two strong subduction interface earthquakes struck Mexico City leading to a large stock of damaged, or even collapsed, reinforced concrete (RC) building structures located in soft soil sites of the former lake-bed zone. The aim of this study is to gain further understanding on the effects of soft-soil seismic sequences on the seismic response of RC framed-buildings. This investigation employed artificial sequences since only two real sequences were gathered during the 1985 earthquakes. The nonlinear response, in terms of peak and residual lateral inter-story drift demands of four RC buildings having 4, 8, 12, and 16 stories, was evaluated. Results show that the relationship of the damaged period of the building (i.e. period of the building after the mainshock) to the predominant period of the aftershock, which is a measure of its frequency content, has a significant impact in the building response.


      PubDate: 2014-04-29T18:55:28Z
       
  • Fragility estimation and sensitivity analysis of an idealized
           pile-supported wharf with batter piles
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Hamid Heidary-Torkamani , Khosrow Bargi , Rouhollah Amirabadi , Nason J. McCllough
      The main objective of the present study is to develop seismic fragility curves of an idealized pile-supported wharf with batter piles through a practical framework. Proposing quantitative limit states, analytical fragility curves are developed considering three engineering demand parameters (EDPs), including displacement ductility factor (µ d ), differential settlement between deck and behind land (DS) and normalized residual horizontal displacement (NRHD). Analytical fragility curves are generated using the results of a numerical model. So, the accuracy and reliability of resulted fragility curves directly depend on how accurate the seismic demand quantities are estimated. In addition, the seismic performance of pile-supported wharves is highly influenced by geotechnical properties of the soil structure system. Hence, a sensitivity analysis using the first-order second-moment (FOSM) method is performed to evaluate the effects of geotechnical parameters uncertainties in the seismic performance of the wharf. Herein, the seismic performance of the wharf structure is simulated using the representative FLAC2D model and performing nonlinear time history analyses under a suit of eight ground motion records. Incremental dynamic analysis (IDA) is used to estimate the seismic demand quantities. As a prevailing tool, adopted fragility curves are useful to seismic risk assessment. They can also be used to optimize wharf-retrofit methods. The results of sensitivity analysis demonstrate that uncertainties associated with the porosity of loose sand contribute most to the variance of both NRHD and µ d . While in the case of differential settlement, the friction angle of loose sand contributes most to the variance.


      PubDate: 2014-04-29T18:55:28Z
       
  • 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
       
  • Seismic performance of SSPQ retaining wall—Centrifuge model tests
           and numerical evaluation
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Xiao-Hua Bao , Guan-Lin Ye , Bin Ye , Yasuki Sago , Feng Zhang
      As temporary structures, steel-sheet-pile-quay (SSPQ) retaining walls have been widely used to counteract excavation problems in Japan not only in urban areas, but also in mountainous areas. The most important features of retaining walls are that they are easy to install in any narrow space, they can be reused many times in different types of soil and, above all, they are strong enough to resist any kind of earth pressure. The shortcoming of retaining walls, however, is that the deformation of the structures may sometimes be rather large, which might become an obstacle for geotechnical engineers wanting to use them as permanent structures. In this paper, centrifuge model tests [1] on the seismic performance of SSPQ retaining walls are simulated systematically with a two-dimensional (2D) dynamic analysis using the finite element method (FEM). In the centrifuge model tests, an SSPQ retaining wall subjected to five consecutive seismic waves is considered. To analyze the influence of the soil density on the performance of the retaining wall and the ground, a middle dense Toyoura sand ground (D r =60%) and a dense Toyoura sand ground (D r =75%) are used. In the analysis, the seismic behavior of the SSPQ retaining wall and the surrounding ground are described separately by beam elements and a cyclic mobility model in which the stress-induced anisotropy, the density and the structure of the ground can be described in a unified way. In order to clarify the influence of the fixed boundary adopted in the centrifuge model vibration tests, an analysis in prototype scale, that completely corresponds to the conditions of the centrifuge model tests, and an analysis in full scale, that corresponds to the real ground conditions, are carried out. By comparing the calculated results with the results of the centrifuge model vibration tests, the anti-seismic capacity of the SSPQ retaining wall and the dynamic performance of the ground during earthquakes are discussed in detail. The accuracy of the evaluation method using FEM is also verified. The purpose of this study is to establish an evaluation approach for the seismic behavior of SSPQ retaining walls as permanent earth-balanced structures.
      Graphical abstract image

      PubDate: 2014-04-29T18:55:28Z
       
  • Earthquake responses of near-fault frame structure clusters due to thrust
           fault by using flexural wave method and viscoelastic model of earth medium
           
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Tielin Liu , Wei Zhong
      An integrated method for simulating earthquake responses of near-fault structure clusters is developed by considering structure cluster consisting of plane frame structures, half-space viscoelastic earth medium and causative fault simultaneously. The seismic responses of near-fault structure cluster of reinforced concrete (RC) frame are simulated during a M w 6.0 hypothetical earthquake, considering viscoelastic attenuation and inhomogeneity of earth medium. It showed that the orbit of structure in the cluster located between the epicenter and rupture forward is in anticlockwise motion during the earthquake induced by thrust fault.


      PubDate: 2014-04-29T18:55:28Z
       
  • Learning of pore pressure response and dynamic soil behavior from downhole
           array measurements
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): David R. Groholski , Youssef M.A. Hashash , Neven Matasovic
      Downhole arrays are deployed to measure motions at the ground surface and within the soil profile, with some arrays instrumented to also record the pore pressure response within soft soil profiles during excitation. The measurements from these arrays have typically been used in conjunction with parametric and nonparametric inverse analysis approaches to identify soil constitutive model parameters for use in site response analysis or to identify averaged soil behavior between locations of measurement. The self-learning simulations (SelfSim) inverse analysis framework, previously developed and applied under total stress conditions, is extended to effective stress considerations and is employed to reproduce the measured motions and pore pressures from downhole arrays while extracting the underlying soil behavior and pore pressure response of individual soil layers. SelfSim is applied to the 1987 recordings from the Imperial Valley Wildlife Liquefaction Array. The extracted soil behavior suggests a new functional form for modeling the degradation of the shear modulus with respect to excess pore pressures. The extracted pore pressure response is dependent on the number and amplitude of shear strain cycles and has a functional form similar to current strain-based pore pressure generation models.


      PubDate: 2014-04-29T18:55:28Z
       
  • Simplified discrete systems for dynamic analysis of structures on footings
           and piles
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Andreas Maravas , George Mylonakis , Dimitris L. Karabalis
      A simplified discrete system in the form of a simple oscillator is developed to simulate the dynamic behavior of a structure founded through footings or piles on compliant ground, under harmonic excitation. Exact analytical expressions for the fundamental natural period and the corresponding damping coefficients of the above system are derived, as function of geometry and the frequency-dependent foundation impedances. In an effort to quantify the coupling between swaying and rocking oscillations in embedded foundations such as piles, the reference system is translated from the footing–soil interface to the depth where the resultant soil reaction is applied, to ensure a diagonal impedance matrix. The resulting eccentricity is a measure of the coupling effect between the two oscillation modes. The amounts of radiation damping generated from a single pile and a surface footing are evaluated. In order to compare the damping of a structure on a surface footing and a pile, the notion of static and geometric equivalence is introduced. It is shown that a pile may generate significantly higher radiation damping than an equivalent footing, thus acting as an elementary protective system against seismic action.


      PubDate: 2014-04-29T18:55:28Z
       
  • Effect of soil depth on inelastic seismic response of structures
    • Abstract: Publication date: June–July 2014
      Source:Soil Dynamics and Earthquake Engineering, Volumes 61–62
      Author(s): Shrabony Adhikary , Yogendra Singh , D.K. Paul
      Effect of depth of soil stratum on estimated inelastic displacement of three typical structures, viz. a four storey building, a continuous bridge, and a tower, is studied and adequacy of the site amplification models of the current design codes and available empirical relationships is examined. The structures are assumed to be located on well-defined sites with varying bedrock depths, and effect of depth on elastic response spectrum, site amplification factor, displacement modification factor and inelastic displacement is studied, numerically, for two values of PGA. It is observed that soil depth has a significant effect on elastic as well as inelastic response of the structures; however, the effect of soil amplification on inelastic response is not as pronounced as in case of elastic response. Therefore, use of empirical site amplification models based on elastic response may be too conservative, for estimating inelastic response.


      PubDate: 2014-04-29T18:55:28Z
       
  • Two-dimensional scattering and diffraction of P- and SV-waves around a
           semi-circular canyon in an elastic half-spa An analytic solution via a
           stress-free wave function
    • Abstract: Publication date: August 2014
      Source:Soil Dynamics and Earthquake Engineering, Volume 63
      Author(s): Vincent W. Lee , Wen-Young Liu
      A well-defined boundary-valued problem of wave scattering and diffraction in elastic half-space should have closed-form analytic solutions. This two-dimensional (2-D) scattering around a semi-circular canyon in elastic half-space subjected to seismic plane and cylindrical waves has long been a challenging boundary-value problem. In all cases, the diffracted waves will consist of both longitudinal (P-) and shear (S-) rotational waves. Together at the half-space surface, these in-plane longitudinal P- and shear SV-waves are not orthogonal over the infinite half-space flat-plane boundary. Thus, to simultaneously satisfy both the zero normal and shear stresses at the flat-plane boundary, some approximation of the geometry and/or wave functions often has to be made, or in some cases, relaxed (disregarded). This paper re-examines this two-dimensional (2-D) boundary-value problem from an applied mathematics points of view and redefines the proper form of the orthogonal cylindrical-wave functions for both the longitudinal P- and shear SV-waves so that they can together simultaneously satisfy the zero-stress boundary conditions at the half-space surface. With the zero-stress boundary conditions satisfied at the half-space surface, the most difficult part of the problem will be solved, and the remaining boundary conditions at the finite-canyon surface are then comparatively less complicated to solve. This is now a closed-form analytic solution of the 2-D boundary-valued problem satisfying the half-space zero-stress boundary conditions exactly.


      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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