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EARTH SCIENCES (472 journals)

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Journal Cover Soil Dynamics and Earthquake Engineering
  [SJR: 1.516]   [H-I: 56]   [14 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0267-7261
   Published by Elsevier Homepage  [3039 journals]
  • A nonlinear approach for the three-dimensional polyhedron scaled boundary
           finite element method and its verification using Koyna gravity dam
    • Authors: Kai Chen; Degao Zou; Xianjing Kong
      Pages: 1 - 12
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Kai Chen, Degao Zou, Xianjing Kong
      Since it was presented, the scaled boundary finite element method (SBFEM) has been shown to be versatile and has been widely applied in structural numerical simulations. However, as it is analytical in the radial direction, nonlinearity inside elements cannot be considered, limiting its application in elastic fields. In this paper, a nonlinear approach for the three-dimensional polyhedron scaled boundary finite element (NPSBFEM3D) is proposed for elasto-plastic analysis to remove this restriction. In NPSBFEM3D, conforming shape functions are constructed using the semi-analytical solution derived from elastic surface elements, while the integrations are accomplished using internal Gauss points in the radial direction instead of integrating on the boundary surface elements. Eventually, the proposed approach can be as conveniently used in elasto-plastic analysis as FEM. This method permits an arbitrary number of faces, which offers a promising adaptive capacity for modelling. Three simulations are conducted to verify the robustness of the presented method.

      PubDate: 2017-02-17T02:23:08Z
      DOI: 10.1016/j.soildyn.2017.01.028
      Issue No: Vol. 96 (2017)
       
  • Fiber-based damage analysis of reinforced concrete bridge piers
    • Authors: Junsheng Su; Rajesh Prasad Dhakal; Junjie Wang
      Pages: 13 - 34
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Junsheng Su, Rajesh Prasad Dhakal, Junjie Wang
      A fiber beam-column element is adopted to simulate the damage development process of reinforced concrete (RC) bridge piers under quasi-static and earthquake loadings considering global buckling and low-cycle fatigue of longitudinal bars. The tensile strain and low-cycle fatigue are used to represent the damage to longitudinal bars while the compression strain is adopted to calculate the damage to the cover concrete. A section damage index is proposed based on the material damage definition and bridge performance assessment. A set of circular RC bridge piers tested under different uniaxial quasi-static loading regimes are adopted to verify the reliability of the fiber beam-column element and the proposed damage model. Square RC columns subjected to different uniaxial and biaxial quasi-static loadings are used to verify the applicable scope of the fiber element and the damage index in biaxial quasi-static loading. In addition, a series of shaking table model tests on square, rectangular and circular piers subjected to bilateral earthquake ground motions are simulated to further verify the versatility of this model. The results show that, the fiber beam-column element can simulate RC columns/piers with different sections and loading regimes with good accuracy. The damage index proposed in this paper is compared against experimental results and other damage indices and it is found that the proposed index can reflect the damage state at any stage and the gradual accumulation of damage in RC columns/piers more convincingly than most other indices available in literature.

      PubDate: 2017-02-17T02:23:08Z
      DOI: 10.1016/j.soildyn.2017.01.029
      Issue No: Vol. 96 (2017)
       
  • Effects of moisture content on the cyclic behavior of crushed tuff
           aggregates by large-scale tri-axial test
    • Authors: Zhigang Cao; Jingyu Chen; Yuanqiang Cai; Chuan Gu; Jun Wang
      Pages: 1 - 8
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Zhigang Cao, Jingyu Chen, Yuanqiang Cai, Chuan Gu, Jun Wang
      The crushed rock aggregates are widely used as road base and subbase fillings of road. The moisture content of the crushed aggregates changes due to rainfalls and water infiltration from the pavement cracks during the road service period, and this usually brings detrimental effects to the performance of road base and subbase. To investigate the effects of moisture content on the resilient modulus and accumulated strain of crushed aggregates under cyclic loadings, comparative experiments on samples under optimum moisture condition and saturated condition were conducted through a large-scale tri-axial apparatus. Different cyclic stress amplitudes, confining pressures and initial deviatoric stresses were also considered in the experiments. Test results show that the change from optimum to saturated moisture content aggravates the accumulated axial strain and reduces the resilient modulus of the aggregates under cyclic loading. The influence of moisture content on the cyclic behavior of CTAs is related to the factors such as cyclic stress ratio and initial deviatoric stress.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.027
      Issue No: Vol. 95 (2017)
       
  • Efficient solution for the diffraction of elastic SH waves by a wedge:
           Performance of various exact, asymptotic and simplified solutions
    • Authors: Víctor H. Aristizabal; Francisco J. Velez; Juan D. Jaramillo
      Pages: 9 - 16
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Víctor H. Aristizabal, Francisco J. Velez, Juan D. Jaramillo
      The diffraction of horizontally polarized shear waves by a semi-infinite wedge in frequency and time domains is studied. In particular, this work focus on the performance of different solutions, including the classical contributions from Macdonald, Sommerfeld and Kouyoumjian & Pathak. In addition, two fully analytical, simplified solutions are proposed using arguments from the so-called geometrical theory of diffraction. The main advantage of the two proposed solutions is the fact that the resulting solutions can be scaled to problems with arbitrary and complex geometries. Moreover, it is found that one of the proposed new solutions is highly efficient in terms of accuracy and computational speed as compared to alternative formulations (approximately 1000 times faster than the Macdonald and Kouyoumjian & Pathak solutions), thus, this important characteristic renders this solution ideal for implementation in GPUs (Graphics Processor Units) for multiscale modeling applications.
      Graphical abstract image

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.040
      Issue No: Vol. 95 (2017)
       
  • Soil and topographic effects on ground motion of a surficially
           inhomogeneous semi-cylindrical canyon under oblique incident SH waves
    • Authors: Ning Zhang; Yufeng Gao; Ronald Y.S. Pak
      Pages: 17 - 28
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Ning Zhang, Yufeng Gao, Ronald Y.S. Pak
      To elucidate the ground motion amplification due to combined soil and topographic effects, an analytical formulation in the framework of classical elastodynamics is derived for the scattering of oblique incident plane SH waves by a semi-cylindrical canyon covered by a local inhomogeneous soil layer with a radially-varying modulus. Allowing the shear modulus of the finite soil layer covering the circular surface of the canyon as a power of the radial distance, the governing equation of motion for the anti-plane shear problem is derived and solved analytically by the method of wave function expansion. The ground motions for both of the homogeneous and inhomogeneous canyons under oblique incident waves can be computed efficiently and a comprehensive set of numerical examples are presented as illustrations. The degree of inhomogeneity of the soil layer and its thickness are found to affect the magnitude and the pattern of ground motion amplification of the cylindrical canyon surface depending on the frequency content, the irregular topography and obliquity of the wave incidence.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.037
      Issue No: Vol. 95 (2017)
       
  • Experimental studies of dynamic properties of Quaternary clayey soils
    • Authors: Wojciech Sas; Katarzyna Gabryś; Alojzy Szymański
      Pages: 29 - 39
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Wojciech Sas, Katarzyna Gabryś, Alojzy Szymański
      The recent significant development of technical infrastructures in Poland, along with the construction of tower blocks, roads, railways and underground rapid transit system, resulted in greater demands for investment projects as well as geotechnical data characterizing the variation of various soil parameters found in the subsoil. The most important parameter, which represents the stiffness of soil deposits, is the shear modulus G. Therefore, this study focused on determining the initial shear modulus of cohesive soils from the area of the capital of Poland. In this research, a set of the resonant column (RC) tests was performed and the influence of three selected factors, i.e. mean effective stress (p’), void ratio (e) and plasticity index (PI), on the low-amplitude shear modulus (G 0 ) was presented and discussed. The results obtained from laboratory tests indicated that the stress state plays an important role for the small-strain shear modulus values of the Polish Quaternary cohesive soils. In contrast, there was no clear trend observed for the significant effect of e or PI on G 0 for the studied soils. Based on the performed tests, the authors proposed the power-law relations for G 0 versus p′ of the forms: G0=3.02p′0.68 and G0=0.82p′0.96.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.031
      Issue No: Vol. 95 (2017)
       
  • A dual-energy-demand-indices-based evaluation procedure of damage-control
           frame structures with energy dissipation fuses
    • Authors: Ke Ke; Michael C.H. Yam; Shuizhou Ke
      Pages: 61 - 82
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Ke Ke, Michael C.H. Yam, Shuizhou Ke
      The primary objective of this research is to extend energy balance concept in seismic behavior evaluation of low-to-medium rise frame systems with energy dissipation fuses dominated by racking deformations. At its core, energy demand indices under ground motions considering both peak responses and cumulative responses are quantified to develop a dual-energy-demand-indices-based procedure for damage-control behavior evaluation. Firstly, based on the experimentally validated hysteretic feature and representative ground motion ensembles, a parametric study is conducted considering the demand indices of the energy factor and the cumulative ductility. Results of the indices distribution and dispersion are presented in detail. Subsequently, a stepwise procedure that accounts for the peak demand and the cumulative demand is constructed. Then, the procedure is applied in prototype structures for validation. Results indicate that the consideration of dual energy demand indices is necessary for evaluation of systems with fuses, and these indices are influenced by structural nonlinear parameters and ground motions properties. The procedure based on the dual energy demand indices can be used to evaluate the structural damage-control behavior with satisfactory accuracy considering the peak response, the cumulative response, and the energy distribution along stories.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.025
      Issue No: Vol. 95 (2017)
       
  • Seismic site amplification in multilayer soil under obliquely incident SH
           waves
    • Authors: H. Djabali-Mohabeddine; B. Tiliouine; M. Hammoutene; M.K. Berrah
      Pages: 83 - 95
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): H. Djabali-Mohabeddine, B. Tiliouine, M. Hammoutene, M.K. Berrah
      2-D seismic site amplification of obliquely propagating anti-plane motions in viscoelastic soil models is presented for two case studies. First, results issued from the application of recursive filters for discrete-time analysis of site amplification under non-vertical wave incidence to the analytical soil layer model of El-Asnam Cultural Center site (North-Western Algeria), are compared to exact solutions from the discrete-frequency approach. In a second stage, seismic site amplification in a multilayer viscoelastic soil profile model of the “500 Residential Apartments” site in the El–Asnam region, under obliquely incident SH waves, is analyzed in detail, using the Thomson-Haskell technique modified to account for both internal and radiation forms of damping. Results of sensitivity analyses performed in an attempt to estimate seismic site amplification of soil surface acceleration time histories under bedrock and rock outcropping input motions, as affected by angle of incidence variations and rock to soil impedance ratios, are discussed.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.010
      Issue No: Vol. 95 (2017)
       
  • Small-strain stiffness and damping of Lanzhou loess
    • Authors: Binghui Song; Angelos Tsinaris; Anastasios Anastasiadis; Kyriazis Pitilakis; Wenwu Chen
      Pages: 96 - 105
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Binghui Song, Angelos Tsinaris, Anastasios Anastasiadis, Kyriazis Pitilakis, Wenwu Chen
      This study examines the small-strain stress-strain properties during cyclic loading of Lanzhou loess deposits, characterized by a very high void ratio (>0.9). Torsional resonant column (RC) tests are performed in order to investigate the effect of water content, confining pressure, consolidation time and soil structure strength on the small-strain stiffness (G 0) and damping (Dmin) of loess. It is proved that shear modulus G 0 at low strain levels is very sensitive to water content while the effect of water content on small-strain damping Dmin is relatively small. As water content W approaches the plastic limit PL, there is a dramatic decrease of G 0 compared to drier loess specimen; G 0 has the tendency to reach a stable or constant value with further increase of water content which is more than the PL of loess. The small strain damping Dmin decreases continuously with water content for unsaturated loess and then tends to increase slightly for almost fully saturated loess. A linear relationship between G 0 and confining pressure σ′m in log-log coordinates for different water contents is observed for Lanzhou loess. Similarly, Dmin decreases linearly with σ′m. A power function is proposed to describe the relationship between G 0 and confining pressure σ′m where the exponent m varies with the water content of loess. G 0 is also affected by the consolidation duration and a power function is proposed between normalized G 0 and normalized consolidation time. G 0 is finally strongly affected by the structure of loess and the type of specimen. For undisturbed loess samples, G 0 is always higher than reconstituted ones and the difference decreases with the degree of saturation; for fully saturated samples the influence of the structure strength between undisturbed and reconstituted samples becomes insignificant. Likewise, Dmin of undisturbed loess is higher than that for remolded loess under the same confining pressure and the difference between them reduces with the degree of saturation as well.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.041
      Issue No: Vol. 95 (2017)
       
  • Shear strength degradation of vibrated dry sand
    • Authors: Nicolas Denies; Alain Holeyman
      Pages: 106 - 117
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Nicolas Denies, Alain Holeyman
      The present paper first provides a state-of-the-art review of experimental researches characterizing the shear strength degradation of vibrated dry sand. Once subjected to vibrations, the shear strength of dry sand exponentially decreases with the acceleration amplitude of vibration to reach a particular state wherein dry sand behaves like a complex fluid: this is the vibrofluid behavior. In the present paper, fundamentals equations and criteria governing the shear strength degradation of vibrated dry sand are summarized. A revisited intrinsic Coulomb criterion, taking into account the absence of pore pressure to explain the shear strength degradation, is discussed and explained considering the existence of a corresponding “shaking” pressure. A “general” Critical State Soil Mechanics, including the effect of the acceleration, is introduced. Finally, a rapprochement with the fundamental researches of the physicists involved in the study of granular matter is proposed allowing the identification of the governing dimensionless parameters and the different dynamic regimes encountered by vibrated dry sands once subjected to shearing.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.01.039
      Issue No: Vol. 95 (2017)
       
  • Seismic plastic–damage analysis of mass concrete blocks in arch dams
           including contraction and peripheral joints
    • Authors: Omid Omidi; Vahid Lotfi
      Pages: 118 - 137
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Omid Omidi, Vahid Lotfi
      Seismic nonlinear analysis of concrete arch dams is a topic having been extensively studied in the last two decades. Due to the existence of different joints within the body of arch dams, the discrete crack (DC) approach utilizing interface elements for the joints is the most realistic method. In fact, it could be the first step to assess the seismic safety of an arch dam. Furthermore, since the mass concrete blocks may crack due to severe ground excitations, a plastic–damage (PD) model well capturing stiffness degradation and permanent deformation due to tensile cracking and compressive crushing might be needed. In this study, a special finite element program called SNACS is developed based on the combined discrete crack and plastic–damage (DC–PD) technique. The dam–reservoir interaction as an important factor affecting the seismic response of arch dams is also treated by the Lagrangian–Eulerian formulation. The joints modeling strategy adopted herein is addressed first and then, a brief review of the plastic–damage model proposed by Lee and Fenves and extended herein to 3-D space is presented. Afterwards, the nonlinear seismic analysis of a typical thin arch dam is performed based on the combined approach and the response is compared with the results of each method. It is emphasized that employing the combined DC and PD models gives more reliable and consistent response in comparison with using DC or PD approaches applied alone. Therefore, the DC–PD technique could be considered as a major step toward a more accurate seismic safety evaluation of concrete arch dams.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.01.026
      Issue No: Vol. 95 (2017)
       
  • Vertical elastic dynamic impedance of a large diameter and thin-walled
           cylindrical shell type foundation
    • Authors: Rui He; Lizhong Wang; Ronald Y.S. Pak; Zhen Guo; Jinhai Zheng
      Pages: 138 - 152
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Rui He, Lizhong Wang, Ronald Y.S. Pak, Zhen Guo, Jinhai Zheng
      This paper studies the vertical vibration of a large diameter and thin-walled cylindrical shell type foundation embedded in a fully saturated porous seabed in contact with a seawater half-space. The solution of the coupled fluid-shell foundation-soil vibration problem is obtained using the ring-load Green's functions for both the shell and the layered fluid-seabed half-space. By considering the fully coupled boundary conditions at the shell-soil interface, the shell vibration problem is reduced to Fredholm integral equations. Through an analysis of the corresponding Cauchy singular equations, the intrinsic singular characteristics of the problem are rendered explicit. With the singularities clear, an effective numerical method involving the Gauss-Chebyshev method is developed to solve the governing Fredholm equations. Selected numerical results for the dynamic contact load distributions, displacements, and dynamic impedance functions are examined based on different shell lengths, soil materials, shell properties, and frequencies of excitation. Moreover, the results are analysed for cases in which there is and is no fluid overlying seabed to examine the effect of fluid.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.01.034
      Issue No: Vol. 95 (2017)
       
  • On the spatial variability of CPT-based geotechnical parameters for
           regional liquefaction evaluation
    • Authors: Chaofeng Wang; Qiushi Chen; Mengfen Shen; C. Hsein Juang
      Pages: 153 - 166
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Chaofeng Wang, Qiushi Chen, Mengfen Shen, C. Hsein Juang
      In-situ index tests, such as the cone penetration test (CPT), are widely used for the site-specific evaluation of liquefaction potential and are getting increased use in the regional mapping of liquefaction hazards. In this work, the spatial variability of CPT-based geotechnical parameters on the liquefaction potential evaluation is assessed through an integrated framework combining an empirical liquefaction model and a multiscale random field model that allows the effective incorporation of soil spatial variability across scales. Within this framework, two approaches, termed the local soil property approach and the averaged index approach, are developed and assessed for the characterization of spatial variability in CPT-based geotechnical parameters. The proposed framework is applied to the probabilistic and spatial assessment of the liquefaction potential of an earthquake-prone region to demonstrate its applicability and to investigate the implications of spatial variability on regional liquefaction susceptibility evaluation.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.02.001
      Issue No: Vol. 95 (2017)
       
  • Seismic performance of a pile-supported wharf: Three-dimensional finite
           element simulation
    • Authors: Lei Su; Jinchi Lu; Ahmed Elgamal; Arul K. Arulmoli
      Pages: 167 - 179
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Lei Su, Jinchi Lu, Ahmed Elgamal, Arul K. Arulmoli
      Considerable three-dimensional (3D) effects are involved in the seismic performance of pile-supported wharves. Such effects include the pile-to-pile interaction mechanisms as dictated by the behavior of the surrounding soil. This interaction might be further affected by potential ground slope settlement/heave, and the constraint of pile connectivity along the relatively rigid wharf deck. In order to capture a number of these salient response characteristics, a 3D finite element (FE) study is conducted herein. The prototype system motivating this study is presented, along with the corresponding numerical details. A realistic multi-layer soil profile is considered, with interbedded relatively soft/stiff strata. Effect of the resulting seismically-induced ground deformation on the pile-supported wharf system is explored. Specific attention is drawn to the noteworthy potential changes in axial force due to variation in pile embedment depth, and the ground slope deformation. The analysis technique as well as the derived insights are of significance to general pile-wharf-ground system configurations.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.01.009
      Issue No: Vol. 95 (2017)
       
  • Dynamic characterization of a biogenic sand with a resonant column of
           fixed-partly fixed boundary conditions
    • Authors: Kostas Senetakis; Huan He
      Pages: 180 - 187
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Kostas Senetakis, Huan He
      The dynamic properties of sands, including the small-strain shear modulus (Gmax) and the small-to-medium strain shear modulus (G) and shear damping (Ds) have been examined extensively in the literature. However, most works published over the past decades have focused on the behavior of soils subjected to isotropic stress paths. In the present study, the dynamic properties of a biogenic sand with origin from Western Australia were examined in the laboratory using a resonant column of fixed-partly fixed boundary conditions. This configuration allows the study of the small-strain shear modulus, the strain-dependent modulus and shear damping of samples subjected to stress anisotropy, which stress conditions may represent more effectively the in-situ state of a soil. For this purpose, proper calibrations of the resonant column were carried out in order to capture the rotational inertia of the apparatus in a wide range of cyclic frequencies covering, in this way, typical resonant frequencies of real soil samples. Basic geotechnical characterization of the biogenic sand was carried out quantifying the shape of the grains and conducting a series of monotonic triaxial tests capturing the peak and critical state friction angles. The dynamic test results indicated a more pronounced effect of the stress anisotropy on Gmax of the biogenic sand in comparison to the corresponding effect on quartz sands reported in the literature. For the limited set of experiments conducted in the study, the effect of stress anisotropy was found less pronounced for the small-to-medium strain shear modulus and shear damping, even though the results indicated a marked drop of shear damping at small strains when the samples were subjected to a deviatoric compressive load.

      PubDate: 2017-02-10T18:52:06Z
      DOI: 10.1016/j.soildyn.2017.01.042
      Issue No: Vol. 95 (2017)
       
  • Dynamic reliability analysis of slopes based on the probability density
           evolution method
    • Authors: Yu Huang; Min Xiong
      Pages: 1 - 6
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Yu Huang, Min Xiong
      Earthquake ground motions display random behavior; therefore, it is necessary to investigate the seismic response of engineering structures using stochastic analysis methods. The probability density evolution method (PDEM) is applied in stochastic seismic response analysis and dynamic reliability evaluation of slope stability. Combining PDEM with finite-element dynamic time-series analysis, this study analyses the stochastic seismic response of a slope under random earthquake ground motion. Comparison between the results of the Monte Carlo stochastic simulation and PDEM analysis demonstrates the effectiveness and high precision of the PDEM method. We assess the stability of the slope under earthquake conditions using the safety factor criterion to obtain the stability probability of the slope. Compared with traditional equilibrium methods, the reliability analysis can directly reflect the failure probability and degree of safety of the slope, demonstrating a novel approach to slope stability assessment using a random dynamic method.

      PubDate: 2017-01-07T00:30:07Z
      DOI: 10.1016/j.soildyn.2016.11.011
      Issue No: Vol. 94 (2017)
       
  • Influences of Biot's compressible parameters on dynamic response of
           vertically loaded multilayered poroelastic soils
    • Authors: Zhi Yong Ai; Li Hua Wang
      Pages: 7 - 12
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Zhi Yong Ai, Li Hua Wang
      The problem is formulated on the basis of Biot's theory and the analytical layer element method, and the global stiffness matrix for the multilayered soil is established by combining continuity conditions of adjacent layers and boundary conditions based on the analytical layer element for a single poroelastic saturated layer in the Hankel transformed domain. Solutions in frequency domain are obtained by taking the Hankel inverse transform. Selected numerical examples are performed to validate the correctness of the present method and to discuss the influences of compressibility parameters of soil grain and pore fluid as well as the influence of soil stratification on vertical displacement and pore pressure.

      PubDate: 2017-01-07T00:30:07Z
      DOI: 10.1016/j.soildyn.2016.12.010
      Issue No: Vol. 94 (2017)
       
  • Transient dynamic response of a shallow buried lined tunnel in saturated
           soil
    • Authors: Y. Wang; G.Y. Gao; J. Yang; X.Y. Bai
      Pages: 13 - 17
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Y. Wang, G.Y. Gao, J. Yang, X.Y. Bai
      Previous research has produced valuable results on the transient dynamic response of tunnels buried in full-space. However, a half-space model is of more practical interest because tunnels normally have finite buried depths. In this paper, the dynamic response of a lined tunnel is studied where the surrounding soil is described using Biot's theory and the lining is described by the theory of elastodynamics. The half-space straight boundary is approximately represented by a convex arc of large radius. In accordance with Graff's addition theorem, the general solutions in a rectangular coordinate system are converted to ones in a polar coordinate system. The solutions for displacements and stresses of both the soil and the lining as well as the pore pressure of the soil in the Laplace transform domain are derived based on boundary conditions. Time domain solutions are then obtained by the use of inverse Laplace transform. Numerical results are presented showing the distributions of peak values of ground displacements, stresses and pore pressures of the soil.

      PubDate: 2017-01-07T00:30:07Z
      DOI: 10.1016/j.soildyn.2016.12.011
      Issue No: Vol. 94 (2017)
       
  • On the peak inter-storey drift and peak inter-storey velocity profiles for
           frame structures
    • Authors: Michele Palermo; Stefano Silvestri; Tomaso Trombetti
      Pages: 18 - 34
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Michele Palermo, Stefano Silvestri, Tomaso Trombetti
      It is well known that peak inter-storey drifts and peak inter-storey velocities are fundamental response quantities to assess the seismic response of a frame structure equipped with added viscous dampers. In the present work, analytical estimations, grounded on the first mode response, of the two response quantities are introduced. Then, a large parametric study is carried out to assess the effectiveness of the proposed predictions. A special attention is devoted to the peak inter-storey velocities and to their sensitivity on the higher modes contribution.

      PubDate: 2017-01-15T00:53:20Z
      DOI: 10.1016/j.soildyn.2016.12.009
      Issue No: Vol. 94 (2017)
       
  • Liquefaction-induced settlement of shallow foundations on two-layered
           subsoil strata
    • Authors: Peyman Ayoubi; Ali Pak
      Pages: 35 - 46
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Peyman Ayoubi, Ali Pak
      Geotechnical design codes have been shifted from classical limit equilibrium analysis toward the performance-based procedures. In foundation design, settlement is the most representative parameter for its performance. Settlement of shallow foundations subjected to earthquake loading and its consequences is one of the most outstanding issues which should be considered in designing different structures. In this study, settlement of shallow footing on two-layered subsoil strata under earthquake loading is of concern. The numerical study presented in this research by means of a 3D dynamic fully coupled u-p analysis, addresses the effect of different parameters on shallow foundation settlement rested on two-layered soil. Results show that the presence of dense layer can mitigate the settlement up to 50% in comparison to uniform liquefiable layer. Putting the results of all the analyzes together, an equation was proposed in order to estimate shallow foundation settlement on two-layered subsoil.

      PubDate: 2017-01-15T00:53:20Z
      DOI: 10.1016/j.soildyn.2017.01.004
      Issue No: Vol. 94 (2017)
       
  • Effects of multilayered porous sediment on earthquake-induced hydrodynamic
           response in reservoir
    • Authors: Shi-Jin Feng; Zhang-Long Chen; H.X. Chen
      Pages: 47 - 59
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Shi-Jin Feng, Zhang-Long Chen, H.X. Chen
      Sediment in a reservoir can be inhomogeneous and layered due to the natural sedimentation process, which highly complexes the hydrodynamic response in the reservoir. Based on an extended transmission and reflection matrix (TRM) method developed in this study, an analytical solution to hydrodynamic response of a water-multilayered porous sediment-bedrock system due to SV wave incident from the bedrock is presented. The uniqueness of the method is that it not only can well accommodate porous sediment with multiple layers, but also is convenient to implement compared to global matrix method. Thus the method is able to reasonably reflect the effects of sediment heterogeneity. The analytical solution is effectively verified against the solution proposed by Wang et al. [28]. Comprehensive parametric study is conducted to investigate the effects of sediment heterogeneity and wave characteristics on the hydrodynamic response in reservoir. Resonant frequencies exist and change with incident angle. Sediment heterogeneity highly influences the hydrodynamic response of the system, especially when the sediment is unsaturated. For sediment with relatively low degree of saturation, the sediment heterogeneity in terms of consolidation level significantly affects the hydrodynamic response at higher order resonant frequencies. Sediment can be divided into numerous layers to reflect the sediment heterogeneity with depth. With the increase of frequency, the needed layer number to precisely describe the sediment heterogeneity increases.

      PubDate: 2017-01-15T00:53:20Z
      DOI: 10.1016/j.soildyn.2017.01.001
      Issue No: Vol. 94 (2017)
       
  • Stochastic seismic response analysis of buried onshore and offshore
           pipelines
    • Authors: Kaiming Bi; Hong Hao; Chao Li; Hongnan Li
      Pages: 60 - 65
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Kaiming Bi, Hong Hao, Chao Li, Hongnan Li
      Previous studies on the seismic responses of offshore pipelines are not only very limited but also usually use earthquake ground motions recorded at the onshore sites as the inputs in the analyses due to the lack of seafloor earthquake recordings and the difficulty to predict seafloor seismic motions. This application may lead to erroneous predictions of offshore pipeline seismic responses, since it has been revealed that the existence of the seawater can significantly suppress the seafloor vertical motions near the P-wave resonant frequencies of the seawater layer. Moreover, the seawater layer can indirectly influence the seafloor motions by changing the water saturation and pore pressure of subsea soil layers, which in turn may obviously affect the propagation of seismic P-wave at the offshore site and therefore the pipeline seismic responses. This paper investigates the stochastic seismic responses of buried onshore and offshore pipelines. The direct and indirect influences of seawater layer on the seafloor seismic motions are explicitly considered by using the recently derived theoretical local site transfer functions. The mean peak seismic responses of buried onshore and offshore pipelines in the axial and lateral directions are stochastically formulated in the frequency domain. The differences between the onshore and offshore pipeline seismic responses are emphasized and the influences of seawater depth and water saturation level of the subsea site on the offshore pipeline responses are discussed.

      PubDate: 2017-01-15T00:53:20Z
      DOI: 10.1016/j.soildyn.2017.01.005
      Issue No: Vol. 94 (2017)
       
  • Recentring and control of peak displacements of a RC frame using damping
           devices
    • Authors: Paulo Silva Lobo; João Almeida; Luís Guerreiro
      Pages: 66 - 74
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Paulo Silva Lobo, João Almeida, Luís Guerreiro
      Recentring capacity is significant for mitigating the repair costs of structures subjected to seismic actions because these costs result from both maximum and residual displacements. A reinforced concrete frame coupled with a variety of energy dissipation devices, namely viscous dampers, steel hysteretic dampers, and passive and semi-active shape memory alloy based devices, was numerically assessed. The nonlinear behaviour, including reinforcing bars bond-slip in beam-column joints, was considered. The passive solution with shape memory alloys and the steel hysteretic dissipators considered were not capable of satisfactorily reducing displacements. Furthermore, the semi-active devices delivered a similar control of the peak displacements to the linear viscous dampers and were capable of recentring the structure, unlike the viscous and the steel hysteretic dampers.

      PubDate: 2017-01-15T00:53:20Z
      DOI: 10.1016/j.soildyn.2017.01.003
      Issue No: Vol. 94 (2017)
       
  • An energy method for deformation behavior of soft clay under cyclic loads
           based on dynamic response analysis
    • Authors: Qing-Lu Deng; Xing-Wei Ren
      Pages: 75 - 82
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Qing-Lu Deng, Xing-Wei Ren
      Soft clay is fragile to be disturbed and to produce deformation under cyclic loads. A simple theoretical energy method is presented to explore the dynamic response of soft clay under cyclic loads, then to discuss its deformation behavior. In the formulation, equations are derived based on general thermodynamic principle and Newton's laws of motion. A series of cyclic triaxial tests are conducted for undisturbed samples of soft clay to verify the proposed method. Cumulative deformation is computed by the proposed approach. Results are compared with the experimental data, and good agreement is achieved. This paper develops a new insight to describe deformation behavior of soft soil under cyclic loads, and to predict the plastic accumulative deformation.

      PubDate: 2017-01-21T20:50:05Z
      DOI: 10.1016/j.soildyn.2016.12.012
      Issue No: Vol. 94 (2017)
       
  • Resistance of inner soil to the vertical vibration of pipe piles
    • Authors: Changjie Zheng; Hanlong Liu; Xuanming Ding; George Kouretzis
      Pages: 83 - 87
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Changjie Zheng, Hanlong Liu, Xuanming Ding, George Kouretzis
      The resistance offered by the inner soil to the vertical oscillation of an end-bearing pipe pile is studied analytically. The differences in the resistance to pile vibrations associated with the inner soil and the outer soil are underlined via example applications and theoretical considerations. Simplified, reduced solutions are also derived, to further investigate the wave propagation mechanisms governing the problem.

      PubDate: 2017-01-21T20:50:05Z
      DOI: 10.1016/j.soildyn.2017.01.002
      Issue No: Vol. 94 (2017)
       
  • Error study of Westergaard's approximation in seismic analysis of high
           concrete-faced rockfill dams based on SBFEM
    • Authors: He Xu; Degao Zou; Xianjing Kong; Xiaohui Su
      Pages: 88 - 91
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): He Xu, Degao Zou, Xianjing Kong, Xiaohui Su
      The error of dynamic stress in slabs of high concrete-faced rockfill dam (CFRD) caused by the Westergaard simplified hydrodynamic pressure method, which is broadly used at present, and the mechanism of the error generation are analysed. The accurate SBFEM hydrodynamic pressure method is also employed for providing comparison benchmark. In this study, a 3D FEM dynamic analysis of a 300m CFRD is conducted under seismic loading in different directions. The results indicate that the Westergaard method produces large errors in the dynamic stress in face slabs along the slope direction. It is necessary to compute the hydrodynamic pressure by the accurate SBFEM in the CFRD-reservoir dynamic interaction analysis.

      PubDate: 2017-01-21T20:50:05Z
      DOI: 10.1016/j.soildyn.2017.01.006
      Issue No: Vol. 94 (2017)
       
  • Time-frequency analysis of instantaneous seismic safety of bedding rock
           slopes
    • Authors: Gang Fan; Li-Min Zhang; Jian-Jing Zhang; Chang-Wei Yang
      Pages: 92 - 101
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Gang Fan, Li-Min Zhang, Jian-Jing Zhang, Chang-Wei Yang
      An earthquake wave has many non-linear and non-stationary components. In current methods for seismic slope stability analysis, the time-frequency-amplitude characteristics of the earthquake waves, which can significantly affect the computation results, are not taken into account. In this paper, formulas for computing the seismic safety factor of bedding rock slopes are derived based on the elastic wave mechanics. The Hilbert-Huang transform (HHT) signal processing technique is employed to identify the time-frequency-amplitude characteristics of the earthquake waves in the time-frequency domain. Then a time-frequency method for computing the instantaneous seismic safety factor of bedding rock slopes, which considers the time-frequency-amplitude characteristics of the earthquake waves simultaneously, is proposed. A shaking table test example is worked out to illustrate the application of the proposed time-frequency analysis method to a bedding rock slope. The instantaneous seismic safety factors of all bedding planes are calculated based on the time-frequency analysis method proposed in this research. The seismic safety factor changes significantly over time, and the seismic safety factor of the upper part of the bedding rock slope is smaller than that of the lower part of the bedding rock slope. Hence the upper part of the bedding rock slope is more vulnerable to seismic damage.

      PubDate: 2017-01-21T20:50:05Z
      DOI: 10.1016/j.soildyn.2017.01.008
      Issue No: Vol. 94 (2017)
       
  • Finite element analysis of the aseismicity of a large aqueduct
    • Authors: Yunhe Liu; Kangning Dang; Jing Dong
      Pages: 102 - 108
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Yunhe Liu, Kangning Dang, Jing Dong
      Finite element analysis has been applied to a large aqueduct to investigate the efficiency of lead rubber bearings (LRBs) in reducing the effects of earthquake shocks. Theoretical relationships have been derived for dynamic interaction of a coupled fluid-solid system such as an aqueduct. A numerical program has been developed by considering the coupled fluid-structure dynamics between the water in the aqueduct and the side wall of the aqueduct and the bilinear deformation characteristics of LRB. The numerical analysis shows that the incorporation of LRBs is a valuable technique in creating aseismicity for a variety of conditions. Since aseismic efficiency varies with LRB type, it is feasible to have an optimal design. The analyses show that LRBs work best with large earthquakes, however, the displacement of the trough sat on top of the LRBs is enhanced so the design of joints within the aqueduct needs special attention.

      PubDate: 2017-01-21T20:50:05Z
      DOI: 10.1016/j.soildyn.2017.01.018
      Issue No: Vol. 94 (2017)
       
  • Experimental and theoretical study on the nonlinear response of full-scale
           single pile under coupled vibrations
    • Authors: Sanjit Biswas; Bappaditya Manna; Dilip Kumar Baidya
      Pages: 109 - 115
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Sanjit Biswas, Bappaditya Manna, Dilip Kumar Baidya
      In this study, an attempt is made to investigate the complex nonlinear behaviour of a reinforced concrete full-scale single pile of 22.0m length and 0.45m diameter subjected to machine induced coupled i.e. horizontal and rocking vibrations. The forced vibration tests were conducted in the field to determine frequency-amplitude responses of the single pile for different eccentric moments. The continuum approach of Novak was used to determine the nonlinear responses of the single pile after incorporating precise values of soil-pile separation lengths and boundary zone parameters. The analytical responses were compared with the experimental responses and it was found that the analytical resonant frequencies and amplitudes were within a reasonable range with the coupled vibration test results. Variation of stiffness and damping of the single pile with frequency were also presented using continuum approach analysis.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.012
      Issue No: Vol. 94 (2017)
       
  • Spectral prediction and control of blast vibrations during the excavation
           of high dam abutment slopes with millisecond-delay blasting
    • Authors: P. Li; W.B. Lu; X.X. Wu; M. Chen; P. Yan; Y.G. Hu
      Pages: 116 - 124
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): P. Li, W.B. Lu, X.X. Wu, M. Chen, P. Yan, Y.G. Hu
      In hydropower projects in Southwest China, large-scale, high-intensity blasts are required to excavate high rock slopes. In these cases, traditional prediction and control methods for blast vibrations are invalid. Thus, a method to predict the time history of blast vibrations on high slopes is proposed, and a blast vibration spectral control scheme based on this method is presented. Additionally, a case study for the abutment slope excavation of the Xiluodu hydropower project is presented. The results indicate that if the delay interval is <20ms or >50ms, a large amount of energy is distributed in the resonant frequency band of the slope; with optimized delay interval of 20–25ms and 45–50ms, the low-frequency compositions of blast vibrations are considerably fewer, and spectral control can be implemented more effectively. Delay intervals of 25 and 50ms are adopted in practice considering the detonator limitation.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.007
      Issue No: Vol. 94 (2017)
       
  • Ground-motion scaling for seismic performance assessment of high-rise
           moment-resisting frame building
    • Authors: Avik Samanta; Yin-Nan Huang
      Pages: 125 - 135
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Avik Samanta, Yin-Nan Huang
      Next generation performance-based earthquake engineering involves the use of a probability framework, which incorporates the inherent uncertainty and variability in seismic hazard, structural and non-structural responses, damage states and economic and casualty losses. One key issue in seismic performance assessment is the scaling of ground motions for nonlinear response-history analysis. In this paper, the impact of ground-motion scaling procedures, including 1) geometric-mean scaling of pairs of ground motions, 2) spectrum-matching of ground-motions, 3) first-mode-based scaling to a target spectral acceleration and 4) maximum-minimum orientation scaling, on the distributions of floor acceleration, story drift and floor spectral acceleration of a sample high-rise building is investigated using a series of nonlinear response-history analyses of a 34-story moment-resisting frame building. The advantages and disadvantages of each ground-motion scaling method are discussed for seismic performance assessment of a 34-story building.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.013
      Issue No: Vol. 94 (2017)
       
  • Static and dynamic field load testing of the long span Nissibi
           cable-stayed bridge
    • Authors: Alemdar Bayraktar; Temel Türker; Janusz Tadla; Altok Kurşun; Arif Erdiş
      Pages: 136 - 157
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Alemdar Bayraktar, Temel Türker, Janusz Tadla, Altok Kurşun, Arif Erdiş
      The static, ambient and dynamic field tests and observations of the long span Nissibi cable-stayed bridge are given in this paper. For this purpose, the ambient vibration tests, static and dynamic loading tests for different truck positions and observational investigations were implemented between May 16–19, 2015. The mobile dynamic measurement system, geodetic measurement system and bridge fixed monitoring system have been used during these tests. The experimental frequencies and mode shapes of the bridge are obtained using the ambient vibration tests with the Enhanced Frequency Domain Decomposition (EFDD) tehcnique. The static displacements of the deck and towers were determined using geodetic instruments for five different fixed truck positions on the bridge deck. The dynamic measurements were taken from the deck, pylons and cables by using the bridge fixed monitoring and the mobile measurement systems for fifteen dynamic load (DL) cases including the passage of trucks throughout the deck. Before, during and after the measurement, observational inspections on the foundations, bearings, joints, deck, cables and pylons have also been realized. The results obtained from the ambient vibration, static and dynamic loading tests are compared with the analytical results of the bridge.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.019
      Issue No: Vol. 94 (2017)
       
  • Seismological parameters derived from local earthquakes reported in Sri
           Lanka
    • Authors: P. Gamage; S. Venkatesan
      Pages: 158 - 178
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): P. Gamage, S. Venkatesan
      Attenuation characteristics of the bedrock beneath Sri Lanka were investigated analysing local seismic data recorded at the country’s broadband seismic network. Digital high-gain records of 13 small to micro earthquakes, magnitude varying from ML 3.6 to 1.5 in the local magnitude scale, were processed for estimating coda Q, Kappa (K) and H/V ratios. The standard single scattering model, which demands the decay rate of backscattered coda waves found at the tail part of seismograms, was applied at eight deferent frequency pass bands from 1 to 19Hz. A parametric study by changing coda time window as 40, 50, 60 and 70s, was carried out to examine the significance of time dependent behaviour in coda Q, if any. A clear trend of increasing Q with the length of time window at low frequencies, and a minor reversing trend at high frequencies were noted. The average variation of Q for all time window cases was in the form, Q = ( 301 ± 17 ) f ( 0 . 67 ± 0 . 02 ) . The near-surface attenuation parameter, Kappa, was estimated by measuring the slope of displacement spectral amplitudes at frequencies below the corner frequency, and has shown to vary between 0.03 and 0.06s for selected locations. The average Kappa for the region was 0.04±0.02s. H/V ratio was found to be close to unity as same as which found in the authors’ previous study for the region, and this implies the country’s upper crust has a negligible amplification in effect. Since uncertainty in estimated parameters was plausible due to numerous reasons, a ground motion comparison between observed and stochastically predicted amplitudes was performed for the validation. Stochastic predictions with Brune’s point source model for stress drops of about 2–4MPa (20–40 bars), exhibited a good compliancy with observed records. Apparent source spectra of the events were also determined after correcting for due path attenuations. Finally, a scenario investigation in the local context was undertaken to identify expected ground motions which can be induced by a possible major event occurred at the capital city - Colombo.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.011
      Issue No: Vol. 94 (2017)
       
  • Site-specific seismic hazard analysis for Calabrian dam site using
           regionally customized seismic source and ground motion models
    • Authors: Paolo Zimmaro; Jonathan P. Stewart
      Pages: 179 - 192
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Paolo Zimmaro, Jonathan P. Stewart
      Probabilistic seismic hazard analysis (PSHA) are performed for routine applications using source models and ground motion models (GMMs) recommended by a government agency (e.g., US Geological Survey) or an expert panel (e.g., SHARE project). For important projects, site-specific PSHA involves critical analysis of GMMs and sources for the application region. We adopt the latter approach for a dam site in Calabria (southern Italy), a high seismic hazard region. We consider area sources as well as fault sources coupled with background zones, tailoring a model developed in the SHARE project for the subject site. We identify several problems with assigned maximum magnitudes for fault and in-slab subduction sources. We also add two sources not previously considered – the crustal Lakes fault and the Calabrian arc subduction interface. We select GMMs that are better constrained in the hazard-controlling range of magnitudes and distances than those typically used in prior Italian applications. Short-period median spectral accelerations at the 2475-year return period exceed those from prior SHARE studies by about 10–15%, and those from the Italian building code by amounts ranging from 15% to 96%. Despite the site being located in a region with finite faults capable of generating large events, the 2475-year hazard is dominated by source zones that allow for earthquakes directly beneath the site.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.014
      Issue No: Vol. 94 (2017)
       
  • Existing prefab R/C industrial buildings: Seismic assessment and
           supplemental damping-based retrofit
    • Authors: Stefano Sorace; Gloria Terenzi
      Pages: 193 - 203
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Stefano Sorace, Gloria Terenzi
      A research study on prefab reinforced concrete buildings designed with older Technical Standards is presented in this paper, where attention is focused on hall-type industrial structures. A representative case study, which includes the main sources of seismic vulnerability, is examined in detail. The possible rigid rotation of the bottom end zone of columns, which are encased in smooth socket-type foundations, and the frictional contact between the neoprene pads situated on top of the columns and the terminal zone of the roof girders are modelled in time-history assessment analyses. Initially carried out by assuming an elastic behaviour of columns, the analyses highlight unsafe response conditions under seismic action scaled at the basic design earthquake level, and near-collapse caused by the loss of support of several girders from the neoprene pads at the maximum considered earthquake level. A second step of the analyses, where plastic behaviour of columns is investigated by incorporating fiber-type plastic hinges at their bottom end sections, shows a remarkable ductility demand, as well as potential collapse induced by the complete loss of support of girders. The high lateral displacements of columns may also cause failure of the fastenings of the connected cladding panels, likely to result in their overturning-induced collapse. Based on these data, a supplemental damping-based retrofit hypothesis is suggested, consisting in the installation of dissipative braces equipped with pressurized fluid viscous spring-dampers. The protective system allows attaining a completely undamaged response of structural and non-structural members, and therefore meeting the requirements of the Immediate Occupancy limit state, up to the maximum considered earthquake level.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.023
      Issue No: Vol. 94 (2017)
       
  • Simulation and mitigation analysis of ground vibrations induced by
           high-speed train with three dimensional FEM
    • Authors: Shi-Jin Feng; Xiao-Lei Zhang; Qi-Teng Zheng; Lei Wang
      Pages: 204 - 214
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Shi-Jin Feng, Xiao-Lei Zhang, Qi-Teng Zheng, Lei Wang
      The high speed railway, which acts as a safer and faster means of transportation, has grown rapidly around the world, especially in China. Meanwhile, the vibration induced by high-speed train (HST) arouses increasing concerns and cannot be ignored. This paper describes ground vibrations with three dimensional models formulated in the time domain using the finite element method (FEM). Absorbing boundaries and Rayleigh damping approach are used to prevent wave reflections from the artificial edges and to simulate the material damping, respectively. Investigations of ground vibration caused by unit load under different speeds and frequencies are given. An inclined classification of ground vibration and the sensitive frequency ranges of surface ground are then found. Moreover, the effects of subgrade treatment and sub-soil treatment on vibration isolation are discussed. It concludes that due to the attenuation effects of subgrade structures on high frequency range, noticeable reductions can be obtained in surface ground vibration. And when a high subgrade or a composite one is applied, the effects are better. The depth of sub-soil treatment would have more positive influence on ground vibration isolation and costs relatively less, compared with its replacement ratio and width. Negative influence may even occur when the sub-soil treatment width becomes larger. Additionally, some useful recommendations are proposed in this paper.

      PubDate: 2017-01-28T21:08:47Z
      DOI: 10.1016/j.soildyn.2017.01.022
      Issue No: Vol. 94 (2017)
       
  • Soft sediment thickness and shear-wave velocity estimation from the H/V
           technique up to the bedrock at meteorite impact crater site, Sao Paulo
           city, Brazil
    • Authors: Irfan Ullah; Renato Luiz Prado
      Pages: 215 - 222
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Irfan Ullah, Renato Luiz Prado
      To obtain shear wave velocity profile for near-surface application many geophysical techniques is used. The most recently used approach is the joint inversion of H/V spectral ratio curve and dispersion curve extracted from the multi-channel analysis of surface waves (MASW) survey. However, in some cases, it is difficult to acquired dispersion curve in engineering application frequency range 1–30Hz. In that situation, dispersion curve can be indirectly inverted from all the available points of the frequency-VRayleigh curve to shear wave velocity and depth. This result a series of (s-wave velocity and depth) values through which a best-fit trend can be passed. The best fit gives us an idea of the rate of shear wave velocity increase with depth and shear wave velocity at one-meter depth. This information can later be utilized in an inversion of Rayleigh wave ellipticity curve.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.015
      Issue No: Vol. 94 (2017)
       
  • Implementation and stability analysis of discrete-time filters for
           approximating frequency-dependent impedance functions in the time domain
    • Authors: Richard Gash; Elnaz Esmaeilzadeh Seylabi; Ertugrul Taciroglu
      Pages: 223 - 233
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Richard Gash, Elnaz Esmaeilzadeh Seylabi, Ertugrul Taciroglu
      This work presents the implementation and stability analysis of a method to account for inertial soil-structure interaction (SSI) in time-history analyses, which is achieved by approximating nominally frequency-dependent foundation impedance functions in the time domain using discrete-time digital filters. The method is demonstrated using a multi-story shear building supported by a rigid disk foundation resting atop a uniform soil half-space and subjected to a horizontal ground motion. The soil-foundation-structure system's equations of motion are numerically integrated to determine its time-history response. The results are verified through comparison to those obtained both through frequency domain analyses and through sampling of the foundation impedance functions at a representative frequency. Numerical stability of the method is examined both analytically and numerically; and it was determined that the stability of the filter and the stability of the time-stepping method adopted do not guarantee that their combination will be stable as well.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.021
      Issue No: Vol. 94 (2017)
       
  • A simple and intuitive procedure to identify pulse-like ground motions
    • Authors: Dante Sebastian Panella; Miguel E. Tornello; Carlos D. Frau
      Pages: 234 - 243
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Dante Sebastian Panella, Miguel E. Tornello, Carlos D. Frau
      Near-fault seismic ground motions are frequently characterized by intense velocity and displacement pulses of relatively long periods that clearly distinguish them from typical far-field ground motions. Intense velocity pulse motions can affect adversely the seismic performance of structures. In response to the realization of the importance of near-fault motions on structural performance, a number of studies have been directed to developing procedures for the identification of ground motions containing velocity pulses. The present paper reviews these studies briefly and presents a simple and efficient procedure to identify pulse-like ground motions based on a new parameter called “development length of velocity time history”. The procedure is applied to a representative series of records, and the results show positive efficiency to identify pulse-like ground motions at low computational cost.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.020
      Issue No: Vol. 94 (2017)
       
  • Seismic rotational stability of gravity retaining walls by modified
           pseudo-dynamic method
    • Authors: Anindya Pain; Deepankar Choudhury; S K Bhattacharyya
      Pages: 244 - 253
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Anindya Pain, Deepankar Choudhury, S K Bhattacharyya
      Seismic stability analysis is an important aspect for design of safe retaining walls in earthquake prone areas. In this study, limit equilibrium method is used for rotational stability analysis of gravity retaining wall on rigid foundation supporting dry cohesionless backfill with modified pseudo-dynamic seismic forces. Proposed method satisfies the zero stress boundary condition at free ground surface and considers the amplification of acceleration. Stability factor F W is proposed to determine the safe weight of the retaining wall against rotational failure under seismic conditions. If the safe weight of the retaining wall is known under static condition then by simply multiplying that with F W can give the safe weight of the retaining wall against rotational failure under seismic condition. Present study shows that wall-soil interaction in various seismic conditions may or may not be in-phase for the entire duration of the input motion. It depends on the properties of the backfill soil, properties of the wall material and also on the frequency content of the input motion. A modified rotating block method is proposed to obtain the rotational displacement under seismic conditions. Present results give higher values of rotational displacements of the wall when compared with the available results by pseudo-static analysis. Hence the present study may be used to design seismically stable retaining wall.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.016
      Issue No: Vol. 94 (2017)
       
  • Centrifuge tests to assess seismic site response of partially saturated
           sand layers
    • Authors: Morteza Mirshekari; Majid Ghayoomi
      Pages: 254 - 265
      Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94
      Author(s): Morteza Mirshekari, Majid Ghayoomi
      Seismic response of unsaturated soil layers may differ from that of saturated or dry soil deposits. A set of centrifuge experiments was conducted to study the influence of partial saturation on seismic response of sand layers under scaled Northridge earthquake motion. Steady state infiltration was implemented to control and provide uniform degree of saturation profiles in depth. The amplification of peak ground acceleration at the soil surface was inversely proportional to the degree of saturation, especially in low period range. The cumulative intensity amplification of the motion was also higher in unsaturated soils with higher suctions. The lateral deformation and surface settlement of partially saturated sand with higher stiffness were generally lower than that in dry soil. Although neglecting the effect of partial saturation in sand layers might be conservative with respect to seismic deformations, it may result in underestimating the surface design spectra.

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2017.01.024
      Issue No: Vol. 94 (2017)
       
  • Development of a regional Vs30 model and typical Vs profiles for
           Christchurch, New Zealand from CPT data and region-specific CPT-Vs
           correlation
    • Authors: Christopher R. McGann; Brendon A. Bradley; Misko Cubrinovski
      Pages: 692 - 705
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): Christopher R. McGann, Brendon A. Bradley, Misko Cubrinovski
      A high-resolution near-surface shear wave velocity (V s ) model is developed for the Christchurch, New Zealand region through the application of a recently developed Christchurch-specific empirical correlation between soil V s and cone penetration test (CPT) data [1,2] to the large, high-spatial-density CPT database [3] available for the Christchurch region. A regional model of time-averaged 30m soil shear wave velocity ( V s 30 ) is developed from this surficial V s model with consideration for the variable surficial geology and underlying non-CPT-penetrable shallow stratigraphy of the region. Typical V s and soil behaviour type index profiles are also developed from the CPT-V s data found within a series of subregions located throughout Christchurch to supplement the general regional characterization provided by the V s 30 model with more detailed and locally relevant descriptions of the soil and velocity profiles typical to the chosen subregions. The high spatial density and extent of the V s model enable it to be used for both general site classification and site-specific understanding of surficial site effects, the applications of which are examined further in the companion work of McGann et al. [4].

      PubDate: 2017-02-04T16:33:17Z
      DOI: 10.1016/j.soildyn.2016.10.025
      Issue No: Vol. 92 (2017)
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: March 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 94


      PubDate: 2017-02-17T02:23:08Z
       
  • Liquefaction potential evaluations by energy-based method and stress-based
           method for various ground motions: Supplement
    • Authors: Kokusho
      Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95
      Author(s): T. Kokusho
      Energy-Based Method for liquefaction potential evaluation was previously proposed and applied to simple soil models and case history sites to show its general usability for a variety of seismic motions. The key of the proposed method is to compare upward wave energy with energy capacity for liquefaction in each layer, though the theoretical background in the energy comparison was not fully addressed in the previous paper. In this supplement, wave energy in upward propagating SH-wave is formulated together with associated dissipated energy, and how to compare it with liquefaction energy capacity is discussed in a simplified evaluation procedure of EBM incorporating cyclic loading soil test data in the laboratory. An additional case study is also conducted to know the effect of the simplification on evaluation results.

      PubDate: 2017-02-04T16:33:17Z
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93


      PubDate: 2017-01-07T00:30:07Z
       
  • Experimental study on effect of fly ash on liquefaction resistance of sand
    • Authors: Mahdi Keramatikerman; Amin Chegenizadeh; Hamid Nikraz
      Pages: 1 - 6
      Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93
      Author(s): Mahdi Keramatikerman, Amin Chegenizadeh, Hamid Nikraz
      A series of cyclic triaxial tests were performed to determine the liquefaction resistance of sand stabilised with fly ash (FA). In order to understand the cyclic behaviour of the FA stabilised sand, the effect of relative density (Dr), FA content, confining pressure (CP) and curing time liquefaction resistance were considered. In the first stage of the laboratory tests, specimens of sand mixed with 2% FA under 50 kPa CP and 0.2 CSR with relative density of 20%, 40%, 60%, and 80%, were tested and compared with untreated soil. The results indicated that mixtures of sand-FA in all relative densities have more resistance to liquefaction failure in comparison with untreated soil, and mixture of sand-FA for relative density of 80% has the greatest resistance value. In the second stage, two types of sand-FA mixture (i.e., 4% and 6% FA) with a relative density of 20% under three ranges of confining pressure, namely 50, 70 and 90 kPa, were tested. The results in this stage suggested that the addition of 6% FA to the sand led to an increase in the cyclic response of the soil to the liquefaction in comparison with the specimens of sand mixed with 4% FA in all tested confining pressures. In the last part of the study, variation of the CSR with the number of cycles to liquefaction for a mixture of sand and 2% FA with 20% relative density under 50, 70 and 90 kPa confining pressure were presented and results indicated that the specimens under greater CP liquefied at earlier cycle numbers and vice versa. In continuing to investigate the effect of curing time, the specimens containing 2% FA were cured for 14 and 28 days and tested under 50 kPa CP and 20% relative density. The result showed that an increase in curing time led to an increase in the liquefaction strength of the sand containing FA.

      PubDate: 2016-12-05T10:20:58Z
      DOI: 10.1016/j.soildyn.2016.11.012
      Issue No: Vol. 93 (2016)
       
  • Stress-strain behavior of soil-rock mixture at medium strain rates –
           Response to seismic dynamic loading
    • Authors: Y. Wang; X. Li; B. Zheng
      Pages: 7 - 17
      Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93
      Author(s): Y. Wang, X. Li, B. Zheng
      This paper aims to investigate the seismic dynamic responses of soil-rock mixtures (SRM) at medium loading strain rates. A total of 130 SRM specimens with four rock block percentage (RBP) of 20%, 30%, 40% and 50% were produced to conduct the uniaxial compressive strength test, at strain rates of 1×10−5 s−1, 5×10−4 s−1, 1×10−3 s−1, 5×10−3 s−1, and 1×10−2 s−1. From the experimental results, SRM presents particular rate-dependence characteristics that are different from each soil and rock material, the peak stress and peak strain first increase and then decrease with the increase of strain rate. The inflection points of rate-dependence are different for specimens with different RBP. The rate-dependence characteristic of SRM is strongly influenced by the rock blocks in the SRM specimen. In addition, crack initiation stress level σci/σf and crack damage stress level σcd/σf do not change with the increases of strain rate. What is more, the experimental results also show that the failure pattern of SRM performs as a spitting failure, shear failure, and conical failure at various strain rates. All the test results proved the particular seismic dynamic responses of SRM, and the interactions between the rock blocks and the soil matrix are the primary factor determining the dynamic response.

      PubDate: 2016-12-11T10:40:39Z
      DOI: 10.1016/j.soildyn.2016.10.020
      Issue No: Vol. 93 (2016)
       
  • Uncertainty quantification for seismic responses of bilinear SDOF systems:
           A semi-closed-form estimation
    • Authors: Peng Deng; Shiling Pei; John W. van de Lindt; Chao Zhang
      Pages: 18 - 28
      Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93
      Author(s): Peng Deng, Shiling Pei, John W. van de Lindt, Chao Zhang
      The ability to accurately quantify uncertainty in structural system seismic responses is a critical component of performance based earthquake engineering (PBEE). Currently, for nonlinear systems, this is achieved empirically using a large number of simulations with different excitation inputs (ground motion suites) and numerically randomized structural model samples. This study focused on one of the simplest nonlinear hysteretic systems, the bilinear single-degree-of-freedom (SDOF) oscillator, to develop a semi-closed-form solution for seismic response uncertainty as a function of 1) intensity-independent ground motion characteristics, 2) structural parameters, and 3) ground motion intensity level. This approach included the development of a parametric model for bilinear system IDA curves with intensity independent ground motion parameters and structural parameters. The accuracy of the proposed model was validated through nonlinear time history analysis (NLTHA) simulations.

      PubDate: 2016-12-11T10:40:39Z
      DOI: 10.1016/j.soildyn.2016.11.016
      Issue No: Vol. 93 (2016)
       
  • Extending the concept of energy-based pushover analysis to assess seismic
           demands of asymmetric-plan buildings
    • Authors: S. Soleimani; A. Aziminejad; A.S. Moghadam
      Pages: 29 - 41
      Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93
      Author(s): S. Soleimani, A. Aziminejad, A.S. Moghadam
      The energy-based pushover analysis was developed in previous studies to address the issues regarding the distortion of capacity curve in conventional pushover procedures. Despite the conceptual superiority of an energy-based approach, its application is currently restricted to 2D structures. This study aims to extend the concept of this approach to asymmetric-plan buildings and bidirectional seismic excitation. For this purpose, a new energy-based multimode pushover analysis is developed. The overall procedure is quite similar to the well-known Modal Pushover Analysis (MPA). In contrast, however, the work done by lateral loads and torques here is used in preference to displacement of the roof center as an index to establish capacity curves. The efficiency of the proposed procedure is evaluated through seismic assessment of a set of one-way asymmetric (asymmetric around one axis) RC shear wall buildings. The results are compared with those of the MPA, ASCE41-13 pushover procedure, and the nonlinear response history analysis as a benchmark solution. Findings show that the proposed procedure can provide more accurate results than the MPA and ASCE41-13 procedures, in estimating the structural demands such as wall-hinge rotations and drift ratios.

      PubDate: 2016-12-11T10:40:39Z
      DOI: 10.1016/j.soildyn.2016.11.014
      Issue No: Vol. 93 (2016)
       
  • An extended modal pushover procedure for estimating the in-plane seismic
           responses of latticed arches
    • Authors: Yang Xiang; Yong-feng Luo; Zu-yan Shen
      Pages: 42 - 60
      Abstract: Publication date: February 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 93
      Author(s): Yang Xiang, Yong-feng Luo, Zu-yan Shen
      The vertical displacements induced by the in-plane vibrating modes of an arch formed structure are as important as the lateral ones. Therefore, the vertical response components should be considered in the modal pushover load patterns for the in-plane seismic performance evaluation of latticed arches. Since the equivalent force of the modal equivalent single-degree-of-freedom (ESDF) system is determined by the base shear in conventional modal pushover procedures, which could not reflect the vertical part of the pushover load, an extended modal pushover analysis (MPA) procedure is proposed in this paper. In the extended MPA, the modal ESDF system of the in-plane vibrating mode of a latticed arch is established by the aid of an energy-based structural stiffness parameter, and the equivalent load of theESDF system is obtained according to the static pushover load factor, instead of using the base shear or other kinds of support reactions. The extended MPA approach not only takes the vertical components of the pushover load patterns into consideration, but also maintains the conceptual understandability and simplicity exhibited by conventional MPA procedures. Numerical examples carried out on two latticed arches demonstrate that the proposed extended MPA is more accurate than the conventional MPA, because in the former, the displacement coupling between horizontal and vertical directions are reflected when the arches are excited by in-plane earthquake actions.
      Graphical abstract image

      PubDate: 2016-12-11T10:40:39Z
      DOI: 10.1016/j.soildyn.2016.12.005
      Issue No: Vol. 93 (2016)
       
 
 
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