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EARTH SCIENCES (471 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  [3041 journals]
  • Double wall barriers for the reduction of ground vibration transmission
    • Authors: C. Van hoorickx; M. Schevenels; G. Lombaert
      Pages: 1 - 13
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): C. Van hoorickx, M. Schevenels, G. Lombaert
      Stiff wall barriers can be effective in reducing the transmission of environmental ground vibration. Up to now, single wall barriers have mostly been studied. In building acoustics, however, double walls are used in order to realize a high level of sound insulation. In this paper, the potential of using double walls in reducing ground vibration transmission is investigated by means of numerical simulations. Two cases are studied: jet-grout walls and concrete walls in a homogeneous soil with elastic properties representative of a sandy soil. For both cases, the three-dimensional free field response due to a point load is computed using a 2.5D finite element methodology. Subsequently, the free field response is computed for a simplified train load. Double jet-grout wall barriers are found to be slightly more effective than single wall barriers, in particular when the thickness of the walls and the intermediate soil matches a quarter Rayleigh wavelength. The largest increase in vibration reduction is found for the area closest to the vibration source, where the vibration levels have the highest values. The performance of concrete wall barriers, however, is mainly determined by the stiffness of the walls, and almost no difference in performance is found for single and double walls.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.006
      Issue No: Vol. 97 (2017)
       
  • Response of the Christchurch water distribution system to the 22 February
           2011 earthquake
    • Authors: D. Bouziou; T.D. O’Rourke
      Pages: 14 - 24
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): D. Bouziou, T.D. O’Rourke
      The effects of transient and permanent ground deformations during the 22 February 2011 earthquake on the Christchurch water distribution system are investigated through geospatial analysis with the most detailed and accurate databases currently available. Using the most recent repair records, ground motion records, high resolution Light Detection and Ranging (LiDAR) data collected before and after the earthquake, and improved screening criteria, repair rates, expressed as repairs/km, for different types of pipeline are correlated with 1) peak ground velocity outside liquefaction areas, and 2) differential ground surface lateral and vertical movements in liquefaction areas. The substantial influence of LiDAR resolution on the relationship between pipeline damage and lateral ground strain indicates sensitivity of repair regressions to the degree of data resolution. Repair regressions of different pipelines show that polyvinyl chloride pipelines are markedly more resilient to earthquake effects than other types of segmental pipelines in the Christchurch system. The analytical process is described in detail for assistance in future investigations with data sets of similar size and complexity.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.01.035
      Issue No: Vol. 97 (2017)
       
  • Effect of initial relative density on the post-liquefaction behaviour of
           sand
    • Authors: Mehdi Rouholamin; Subhamoy Bhattacharya; Rolando P. Orense
      Pages: 25 - 36
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Mehdi Rouholamin, Subhamoy Bhattacharya, Rolando P. Orense
      Understanding the behaviour of soils under cyclic/dynamic loading has been one of the challenging topics in geotechnical engineering. The response of liquefiable soils has been well studied however, the post liquefaction behaviour of sands needs better understanding. In this paper, the post liquefaction behaviour of sands is investigated through several series of multi-stage soil element tests using a cyclic triaxial apparatus. Four types of sand were used where the sands were first liquefied and then monotonically sheared to obtain stress-strain curves. Results of the tests indicate that the stress-strain behaviour of sand in post liquefaction phase can be modelled as a bi-linear curve using three parameters: the initial shear modulus ( G 1 ), critical state shear modulus ( G 2 ), and post-dilation shear strain ( γ p o s t − d i l a t i o n ) which is the shear strain at the onset of dilation. It was found that the three parameters are dependent on the initial relative density of sands. Furthermore, it was observed that with the increase in the relative density both G 1 and G 2 increase and γ p o s t − d i l a t i o n decreases. The practical application of the results is to generate p-y curves for liquefied soil.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.007
      Issue No: Vol. 97 (2017)
       
  • Soil liquefaction in Kathmandu valley due to 25 April 2015 Gorkha, Nepal
           earthquake
    • Authors: Dipendra Gautam; Filippo Santucci de Magistris; Giovanni Fabbrocino
      Pages: 37 - 47
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Dipendra Gautam, Filippo Santucci de Magistris, Giovanni Fabbrocino
      The April 25, 2015 Gorkha earthquake (MW 7.8) affected central Nepal and neighboring areas. Kathmandu valley witnessed severe damage in terms of structural collapse and casualties. Apart from this, soil liquefaction in the form of sand blows and lateral spreading were observed in 12 locations. Soil liquefaction in Kathmandu valley during 1934 (MW 8.1) earthquake was believed to be one of the major cause of damage in structures and lifelines but detail records are not available. To fulfill the gap of documentation in case of strong earthquake events like the Gorkha earthquake, field reconnaissance and collection of samples from each sand blow location have been carried out. In addition to this, numerical analyses based on geotechnical investigation records for seven locations that manifested sand blows have been performed. Common approach of liquefaction susceptibility analysis based on standard penetration resistance is found to be consistent with the surface manifestations. Our comparison between existing susceptibility maps and results of numerical analyses as well as field evidence concludes that the existing susceptibility maps are unrepresentative.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.03.001
      Issue No: Vol. 97 (2017)
       
  • Effects of frequency contents of aftershock ground motions on reinforced
           concrete (RC) bridge columns
    • Authors: Moochul Shin; Byungmin Kim
      Pages: 48 - 59
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Moochul Shin, Byungmin Kim
      This study focuses on exploring effects of frequency contents of aftershock ground motions on seismic responses of reinforced concrete (RC) bridge columns. It has been well recognized that RC columns damaged by a sizeable main shock event become more vulnerable to following aftershocks. Therefore, it is essential to use proper main shock-aftershock sequential ground motions in seismic analyses to ensure the safety and integrity of infrastructure. Using frequency –invariant scaling factors, conventional methods were developed in the past. These methods combine sequential ground motions when performing a time history nonlinear analysis. However, these conventional methods neglect frequency contents of aftershock ground motions, which are usually different from those of main shock ground motions. This research demonstrates the importance of properly representing aftershock ground motions in estimating seismic responses of RC columns, and presents the differences in frequency contents between aftershock ground motions and the corresponding main shock ground motions. Time history seismic analyses using a finite element analysis program OpenSees are carried out. First, main shock motions recorded during the 1994 Northridge, California, the United States of America, the 1997 Umbria-Mache, Italy and the 1999 Chi-Chi, Taiwan earthquakes are used in this study. Then, the corresponding aftershock motions are selected or obtained: (1) from recordings during the seismic events, (2) by scaling main shock (which represents a traditional method), or (3) by spectrally matching main shock motions to the aftershock motions. The peak displacements and residual displacements of the RC columns using the spectrally matched motions are closer to those results using real aftershock motion records, as opposed to using the scaled motions. This demonstrates that the frequency contents of aftershock ground motions have significant impacts on the seismic responses of RC columns.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.012
      Issue No: Vol. 97 (2017)
       
  • Dynamic variability response functions for stochastic wave propagation in
           soils
    • Authors: Theofilos-Ioannis Manitaras; Vissarion Papadopoulos; Manolis Papadrakakis
      Pages: 60 - 73
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Theofilos-Ioannis Manitaras, Vissarion Papadopoulos, Manolis Papadrakakis
      In this paper, shear wave propagation in soils is examined in a stochastic context considering spatial variability of the shear modulus soil parameter. To this purpose, the recently established concept of dynamic mean and variability response functions (DMRF, DVRF) is reformulated in the framework of stochastic finite element analyses of shear wave propagation problems in order to efficiently calculate the response time history statistics of the soil surface. Similarly to the approximation formulas of classical VRFs, a fast Monte Carlo simulation procedure is implemented to numerically evaluate the above functions in the time domain. The main advantage of the proposed methodology lies on the independence of the DMRF and DVRF on the marginal probability density function and correlation structure of the stochastic system parameter, which in our case is assumed to be the inverse of the soil shear modulus 1 / G . By integrating the product of the spectral density of 1 / G with the DMRF and DVRF, the mean and variance of the ground response are obtained at each time step of the dynamic analysis. The method also allows for the estimation of time dependent but spectral and probability distribution free upper bounds of the response mean and variance. To illustrate the efficiency and applicability of the proposed approach, stochastic finite element analyses of wave propagation of a Ricker synthetic wavelet as well as a recorded earthquake motion in 1D and 2D soil domains are performed and a sensitivity analysis is carried out with respect to various correlation structures of the underlying random fields representing 1 / G . The accuracy of the proposed methodology is validated with comparison to direct Monte Carlo simulation. Useful conclusions regarding the sensitivity of the system response to the spectral characteristics of the underlying random fields representing 1 / G are drawn.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.004
      Issue No: Vol. 97 (2017)
       
  • Equivalent damping of bilinear hysteretic SDOF system considering the
           influence of initial elastic damping
    • Authors: Tao Liu; Bruno Briseghella; Qilin Zhang; Tobia Zordan
      Pages: 74 - 85
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Tao Liu, Bruno Briseghella, Qilin Zhang, Tobia Zordan
      The premise of equivalent linearization method is that the peak response of an inelastic system can be estimated as the peak response of a linear elastic system having reduced stiffness and increased damping. Different approaches have been used to determine the properties of the equivalent linear system, in particular the equivalent damping ratio. In general, equivalent damping is specified as the sum of elastic and hysteretic component, where the former is assumed to be constant, and the latter depends on the ductility and hysteresis model. It is found that, however, many studies only focus on the definition of hysteretic damping and omit the influence of elastic damping on the prediction accuracy of equivalent linearization method. Motivated by this limitation, comprehensive parametric analysis is performed in this paper based on bilinear hysteretic SDOF systems to identify the influence of elastic damping. Results show that elastic damping has significant influence on the estimation accuracy of equivalent linearization method. To improve the estimation accuracy of equivalent linearization method, improved method of equivalent damping is proposed by considering the influence of elastic damping. It is found that the proposed method is able to provide accurate and conservative values of equivalent damping for practical design of base isolation systems.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.01.017
      Issue No: Vol. 97 (2017)
       
  • Comparative study of 2D and 2.5D responses of long underground tunnels to
           moving train loads
    • Authors: Y.B. Yang; Xujie Liang; Hsiao-Hui Hung; Yuntian Wu
      Pages: 86 - 100
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Y.B. Yang, Xujie Liang, Hsiao-Hui Hung, Yuntian Wu
      A comparative study is conducted for the responses of soil-tunnel systems to moving train loads using the 2D and 2.5D finite/infinite element approaches, considering the effects of train speed, rail roughness and floating slab. Focus is placed on the wheel-rail interaction forces in the presence of rail roughness. The following are the major findings of this paper: (1) For all the cases studied, the 2D soil response is always higher than the 2.5D response. (2) The 2D result (with plane strain condition) is the limit of the 2.5D analysis with infinite train speed for smooth rails. (3) The 2D frequency response function (FRF) is contributed by frequencies of the whole range, being less sensitive to variation in roughness frequencies, while the 2.5D FRF is affected seriously by the frequencies of rail roughness. (4) With the floating slab tracks, the velocity and acceleration predicted of the soil are largely reduced for frequencies above the threshold using both approaches. But for frequencies below the threshold, the 2D approach shows higher amplified response. In short, the 2D approach saves tremendous computation time, as the system matrices is relatively smaller. But the 2.5D approach is more realistic, since it can account for various factors of the half space, including rail roughness and wave transmission along the tunnel axis.

      PubDate: 2017-03-16T00:22:39Z
      DOI: 10.1016/j.soildyn.2017.02.005
      Issue No: Vol. 97 (2017)
       
  • Inelastic design spectra based on the actual dissipative capacity of the
           hysteretic response
    • Authors: Enzo Martinelli; Roberto Falcone; Ciro Faella
      Pages: 101 - 116
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Enzo Martinelli, Roberto Falcone, Ciro Faella
      This work is intended at generalising the μd-T-Rμ relationships, currently available in the literature for defining inelastic design spectra, with the aim to take into account the actual dissipative capacity of structural systems. In fact, the inelastic spectra currently adopted in Nonlinear Static Analyses are generally based on an ideal elastic-perfectly plastic behaviour. Therefore, a more general hysteretic law is considered for parameterising the dissipative capacity of the structural systems under consideration. Non Linear Time History analyses are carried out for evaluating their dynamic response. A calibration of the aforementioned μd-T-Rμ relationships is proposed for enhancing the accuracy of inelastic seismic design spectra and, hence, the resulting relationships widely adopted in seismic analysis procedures, such as the N2 Method.

      PubDate: 2017-03-21T00:40:27Z
      DOI: 10.1016/j.soildyn.2017.03.006
      Issue No: Vol. 97 (2017)
       
  • A Multi-step approach to generate response-spectrum-compatible artificial
           earthquake accelerograms
    • Authors: Khaldoon A. Bani-Hani; Abdallah I. Malkawi
      Pages: 117 - 132
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Khaldoon A. Bani-Hani, Abdallah I. Malkawi
      Time history records are essential for nonlinear dynamic analysis to determine the response of structures. Considering lack of enough earthquake records, generation of artificial earthquake records and spectrum-matched records are the best method in this regard. This study is motivated by real life applications of designing new structures or evaluating the performance of current ones in Afghanistan where two structures are to be designed and built to withstand earthquakes. In this paper, design response spectrum and time history records are generated for two sites located within the city of Kabul, Afghanistan. The Probabilistic Seismic Hazard Assessment (PSHA) results are employed initially to produce the required parameters and data. Then, the generalized nonstationary Kanai-Tajimi model is applied to simulate the ground acceleration time history using the identified characteristics of the site from preliminary ARMA (Auto Regressive Moving Average) analysis and the site-specific analysis. The response spectrum is developed and iteratively compared to the ARMA model and the site-specific spectrum until a satisfactory match is achieved. Finally, the time domain description of the spectrum-compatible artificial earthquake record is developed exploiting inverse FFT of the design response spectrum. The total errors in spectral matching generated accelerograms are compared to results from a commercially available software. Results demonstrated the effectiveness and robustness of the adapted approach.

      PubDate: 2017-03-21T00:40:27Z
      DOI: 10.1016/j.soildyn.2017.03.012
      Issue No: Vol. 97 (2017)
       
  • Effect of silt on post-cyclic shear strength of sand
    • Authors: Reza Noorzad; Milad Shakeri
      Pages: 133 - 142
      Abstract: Publication date: June 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 97
      Author(s): Reza Noorzad, Milad Shakeri
      Adding non-plastic fines to sand can greatly change its behavior. Size difference between sand and silt particles is the main reason which causes this change. While post-cyclic and post-liquefaction behavior of clay and clean sand has been widely studied, silty sand is wrongly considered to behave like clean sand and researches usually do not focus on it. In silty sand, through low cohesion, applying cyclic load can displace particles and result in heterogeneity within the mixture. Even if liquefaction does not occur, rearrangement of soil particles can affect monotonic ultimate strength. This study, with a series of post-cyclic monotonic triaxial tests, has shown that in sand with a considerable amount of silt, cyclic loading can change the ultimate state strength. In sand with 15% silt it decreases and in sand with 30% silt it increase the ultimate state strength. Changes are negligible in clean sand or sand with 5% silt.

      PubDate: 2017-03-21T00:40:27Z
      DOI: 10.1016/j.soildyn.2017.03.013
      Issue No: Vol. 97 (2017)
       
  • 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)
       
  • The effect of foundation embedment on net horizontal foundation input
           motion: The case of strip foundation with incomplete contact to nearby
           medium
    • Authors: Hossein Jahankhah; Pouran Fallahzadeh Farashahi
      Pages: 35 - 48
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Hossein Jahankhah, Pouran Fallahzadeh Farashahi
      This investigation is coordinated for the case of strip embedded foundation with incomplete contact to surrounding medium to uncover some aspects of kinematic interaction. The extracted results of finite element analyses are presented in three stages. First, horizontal and rotational foundation responses besides a recently introduced net horizontal foundation input motion are studied extensively. Then, the difference between net horizontal foundation input motion and free field motion is discussed here. In addition, the affected response spectra by considering such net horizontal input motion are illustrated. The results indicate that the role of frequency content of records to take kinematic interaction effects becomes highlighted for the case of incomplete contact with respect to fully bounding state. Also, kinematic interaction has considerable role in amplifying peak accelerations of net horizontal foundation input motion and related response spectra for specific cases. Such amplification is notable for the case of slender structures rested on foundations with zero contact of side walls to surrounding soil. This intensification would sometimes move traditionally designed systems, in which incomplete contact between soil and subterranean walls is ignored, to unconservative states.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.015
      Issue No: Vol. 96 (2017)
       
  • Urban-scale seismic fragility assessment of RC buildings subjected to
           L'Aquila earthquake
    • Authors: Carlo Del Gaudio; Paolo Ricci; Gerardo M. Verderame; Gaetano Manfredi
      Pages: 49 - 63
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Carlo Del Gaudio, Paolo Ricci, Gerardo M. Verderame, Gaetano Manfredi
      A damage scenario on a database of Reinforced Concrete (RC) buildings subjected to the 6 th April 2009 L'Aquila earthquake is derived from the application of the POST (PushOver on Shear Type models) procedure, a simplified analytical methodology for seismic vulnerability assessment of RC buildings at large scale. Based on the simplified assumption of shear type modelling, POST methodology allows the derivation of the non-linear static behaviour of RC buildings accounting for the influence of infill panels. The seismic capacity is evaluated in terms of spectral intensity measures at different Damage States (DSs) based on the displacement capacity of structural and non-structural elements. DSs and the corresponding displacement thresholds are defined through the interpretation of the observational-based DSs provided by the European Macroseismic Scale EMS-98. Finally, a seismic fragility assessment is carried out, introducing random variables and adopting a Monte Carlo simulation technique. A database of 250 RC buildings located in the Municipality of L’Aquila is considered. The predicted damage scenario is compared with the observed post-earthquake damage collected from post-earthquake emergency survey forms. The influence of certain parameters on the derivation of damage scenarios is investigated, namely the assumptions made regarding the distribution of infill panels within the analysed buildings (i.e., internal partitions) and on spectral shape. The reliability of the adopted simplified analytical procedure and of the assumed mechanical interpretation of damage classification of EMS-98 are validated through the comparison of the predicted and observed percentage of buildings in each DS and distributions of damage to structural components (vertical structures and infill panels).

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.003
      Issue No: Vol. 96 (2017)
       
  • Principal component analysis for a seismic usability model of unreinforced
           masonry buildings
    • Authors: Maria Zucconi; Luigi Sorrentino; Rachele Ferlito
      Pages: 64 - 75
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Maria Zucconi, Luigi Sorrentino, Rachele Ferlito
      This paper develops a model to forecast unreinforced masonry buildings’ usability, i.e. the condition of a building being habitable or occupiable after a seismic event. The model is based on scores given to seven building parameters that are usually easy to survey: building position within the structural aggregate, number of storeys above ground, construction timespan, structural class, presence of strengthening interventions, roof type, and pre-existing damage to structural elements. Usability coefficients are calibrated for each category of each parameter, by varying macroseismic intensity and regressing data from the 2009 L’Aquila earthquake in central Italy. The parameters contribute to the creation of a synthetic index, according to weights or loading computed through principal component analysis. Usability probability matrices are determined and they can be used for territorial scale scenario assessment, as shown with an application to an entire historical centre.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.014
      Issue No: Vol. 96 (2017)
       
  • Influence of flood-induced scour on dynamic impedances of pile groups
           considering the stress history of undrained soft clay
    • Authors: Fayun Liang; Hao Zhang; Maosong Huang
      Pages: 76 - 88
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Fayun Liang, Hao Zhang, Maosong Huang
      Flood-induced scour causes loss of lateral support at bridge foundations and thus modifies their dynamic impedances, which will in turn influence the dynamic behavior and the seismic response of bridges located in seismically active flood-prone regions. When evaluating the seismic performance of scoured bridges, however, few efforts have been made to analyze the dynamic impedances of their foundations, and possible changes in stress history of the remaining soils are also ignored. In reality, the remaining soils around pile foundations undergo an unloading process due to scour and their over-consolidation ratios are increased, which can be expected to change the properties of the remaining soils. Therefore, a three-dimensional numerical model, in which the pile-soil-pile interaction and the radiation problem are accounted for by means of the elastodynamic Green's functions that permit the mutual interactions between all the piles of the group consistently and simultaneously, is employed in this paper to investigate the influence of flood-induced scour on the dynamic impedances of pile groups in soft clay. Accordingly, the key soil parameter of the elastodynamic Green's functions, i.e., Young's modulus of soft clay, is modified in this model to take into account the stress history effect due to scour. A case study to evaluate the dynamic impedances of 3×3 and 4×4 pile groups with various scour depths and pile spacing, considering or ignoring stress history effect, is discussed in this paper. The results show that ignoring the effect of stress history of the remaining soft clay will overestimate the scour affected dynamic impedances of pile groups, which are found to be reduced significantly as the scour depth increases.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.009
      Issue No: Vol. 96 (2017)
       
  • Safe distance of cultural and historical buildings from subway lines
    • Authors: Javad Sadeghi; M. Hassan Esmaeili
      Pages: 89 - 103
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Javad Sadeghi, M. Hassan Esmaeili
      Construction and operation of subways (metros) closed to historical sites have been one of the main concerns of the world heritage protection bodies such as UNESCO. While metros alleviate condense traffic conditions and boost the tourism industry, the metro induced vibrations might damage cultural and historical structures (CHS). Although there have been various studies into the metros vibration characteristics and the CHS protection methods, there is still a lack of sufficient investigations into the measures by which a safe distance of the CHS to the metro can be derived. In response to this need, a thorough theoretical and experimental investigation was made in this research, aiming at developing a safe distance prediction graphs (SD). For this purpose, a finite element model of the track and the surrounding media was developed. The advantage of the model over the current ones is the consideration of the real (in situ) train loading conditions as an input. The model was validated by comparisons of its results with those of a comprehensive field measurement carried out in this research. New classifications of the CHSs and the track sub-structure form the aspect of metro-induced vibrations were developed in this research. Through parametric analyses of the model, the SD was developed for the first time as a function of metro characteristics, geo-mechanical properties of the media between the metro and the CHS, and the type of CHS. The effectiveness and practicability of the SD in construction of new subway lines were illustrated. It was shown that the SD graphs developed here can be taken as an effective tool for the design of subway lines in historical cities.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.008
      Issue No: Vol. 96 (2017)
       
  • Inelastic displacement ratios of SSI systems
    • Authors: Ertugrul Demirol; Ashraf S. Ayoub
      Pages: 104 - 114
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Ertugrul Demirol, Ashraf S. Ayoub
      This paper presents the effect of soil-structure interaction on seismic inelastic displacement ratios of Single Degree of Freedom (SDOF) systems. Existing methods used in the past assumes the soil to be rigid. Through simplified equivalent fixed-base methods, the effect of soil-structure interaction (SSI) on the inelastic behaviour of structures is evaluated for different soil parameters using effective period and damping values. Using a degrading modified Clough model, the influence of different types of degradation is accounted for, for SDOF systems with periods ranging from 0.2 to 1.4s. In total 300 different earthquake motions recorded on firm soil condition with magnitudes greater than 5 and peak ground acceleration (PGA) values greater than 0.08g were selected. These records were scaled to the same hazard level and applied on five experimentally-tested reinforced concrete columns selected from the Pacific Earthquake Engineering Research Centre database. A total of 384,000 dynamic analyses were conducted. The results of the soil interacting systems are compared with the fixed-base case for different strength reduction factors (R) and foundation aspect ratios (h/r) for a range of NEHRP soil types C and D properties. These results show that the maximum inelastic displacements for soil type D are greater than those of soil type C and the fixed-base case. Particularly for periods less than 0.6s with large aspect ratios, the effects of soil-structure interaction should be accounted for. Finally, the collected data was used to derive mathematical expressions for inelastic displacement ratios of SSI systems, suitable for use in performance-based seismic evaluation of structures.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.010
      Issue No: Vol. 96 (2017)
       
  • Structural and non-structural intensity measures for the assessment of
           base-isolated structures subjected to pulse-like near-fault earthquakes
    • Authors: Fabio Mazza; Rodolfo Labernarda
      Pages: 115 - 127
      Abstract: Publication date: May 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 96
      Author(s): Fabio Mazza, Rodolfo Labernarda
      The objective of the present work is to improve selection procedures for intensity measures (IM) to be used for scaling near-fault earthquakes, in order to minimize the variability in the prediction of engineering demand parameters (EDPs). To this end, the predictive capability of nine spectral IMs, among the most commonly used in the literature, is investigated with reference to three EDPs evaluated for base-isolated structures subjected to near-fault earthquakes, which can be characterized by pulse-type motions in the horizontal direction and significant vertical component. A six-storey reinforced concrete (r.c.) framed building originally designed as fixed-base, in compliance with a former Italian seismic code for a medium-risk zone, is retrofitted by means of friction pendulum bearings (FPBs), to attain performance levels imposed by the current Italian code in a high-risk seismic zone. The nonlinear dynamic analysis is carried out by a lumped plasticity model for the r.c. frame members, including a 26-flat surface axial load-biaxial bending moment elastic domain at the end cross-sections, and a nonlinear force-displacement law for the FPBs, that consider variable axial load combined with friction coefficient as function of the sliding velocity. Two sets of accelerograms are considered, consisting of near-fault records with significant horizontal pulses, selected by using a pulse index, and significant vertical component, selected by the ratio between the peak of the vertical and the horizontal ground acceleration.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.02.013
      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)
       
  • 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)
       
  • 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)
       
  • 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)
       
  • 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)
       
  • Seismic response of liquefiable sloping ground: Class A and C numerical
           predictions of centrifuge model responses
    • Authors: K. Ziotopoulou
      Abstract: Publication date: Available online 7 March 2017
      Source:Soil Dynamics and Earthquake Engineering
      Author(s): K. Ziotopoulou
      Numerical simulations of the LEAP centrifuge tests are performed to validate the numerical modeling approach and to provide insight on our capacity to simulate and predict the equivalent field responses. Measured and recorded dissipation patterns, accelerations, and displacements for a sloping ground of medium dense Ottawa Sand subjected to a sinusoidal acceleration input motion are compared to Class A and C [12] numerical predictions performed in FLAC using the constitutive model PM4Sand. The constitutive model calibration process is based on two cases of cyclic strength for the sand and is performed against the available laboratory data as well as published data for Ottawa sand. Computed results are illustrated for selected cases and compared to measurements. Key observations, mechanisms, and time histories are reasonably captured and bounded by the simulations showing that FLAC, PM4Sand as well as the overall employed methodology have the capability to predict the response of liquefiable sloping ground. The soil properties are found to be playing the most important role in capturing the finer details of the response, and parametric investigations of the soil stiffness and permeability are further needed to refine the predictions.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.01.038
       
  • LEAP-GWU-2015 centrifuge test at UC Davis
    • Authors: Trevor J. Carey; Takuma Hashimoto; Daniel Cimini; Bruce L. Kutter
      Abstract: Publication date: Available online 6 March 2017
      Source:Soil Dynamics and Earthquake Engineering
      Author(s): Trevor J. Carey, Takuma Hashimoto, Daniel Cimini, Bruce L. Kutter
      For the LEAP-GWU-2015 exercise, a relatively simple centrifuge test was conducted in parallel at 6 centrifuge facilities including the University of California Davis (UCD). The experiment consisted of a submerged medium dense clean sand with a 5° slope subjected to 1Hz ramped sine wave base motion in a rigid container. This paper explains several details of the experiment at UCD including intended and unintended deviations from the specification and the implementation of new techniques for measurement of saturation of the centrifuge model. One unintended critical deviation was the use of pore fluid that was more viscous than specified; this had significant effect on the pore pressure dissipation time. The other important deviation from the specification was the incomplete ground motion sequence. While it is not ideal for purposes of determining the replicability of centrifuge tests, the differences between experiments diversifies the data available for validation of numerical models.

      PubDate: 2017-03-09T06:56:09Z
      DOI: 10.1016/j.soildyn.2017.01.030
       
  • Editorial Board / Aims and Scope
    • Abstract: Publication date: April 2017
      Source:Soil Dynamics and Earthquake Engineering, Volume 95


      PubDate: 2017-02-24T03:04:42Z
       
  • 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
       
 
 
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