ALBERT

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Zhijun Dai, Xiaojun Li, Su Chen, Sicheng Zhao, Zhenghui Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Baseline correction in time series of ground motion is a challenging problem in research pertaining to strong ground motion. In previous studies in this area, numerous methods have been proposed to identify baseline drift. However, there is no systematic approach to verify the proposed methods. In this paper, we propose a vision-based approach to evaluate baseline correction methods quantitatively. In addition, for our proposed baseline correction method based on L1-norm optimization, we analyze the method in detail and provide a thorough analysis of the method based on experimental data. From the comparison, our method shows good performance in recovering the baseline.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Guillermo M. Álamo, Juan J. Aznárez, Luis A. Padrón, Orlando Maeso〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of the soil profile on the maximum kinematic bending moments of pile foundations is investigated in this work. For this purpose, power-law, linear and equivalent homogeneous profiles based on real boreholes are selected together with characteristic dimensions of pile foundations. The equivalence between the homogeneous and variable profiles is established in terms of the average shear wave velocity 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" altimg="si22.svg"〉〈msub〉〈mrow〉〈mi〉V〈/mi〉〈/mrow〉〈mrow〉〈mi〉s〈/mi〉〈mo〉,〈/mo〉〈mn〉30〈/mn〉〈/mrow〉〈/msub〉〈/math〉 suggested by the codes for site classification. Envelopes of maximum kinematic bending moments are computed through the application of the standard frequency-domain method and accelerograms corresponding to real earthquake events. The pile harmonic response is computed through an efficient linear-elastic numerical model based on the reciprocity theorem in elastodynamics and the use of Green’s functions for the layered half space. In this model, piles are considered as Timoshenko’s beam elements and treated as load lines within the soil formulation. The obtained results show a large influence of the variability of the soil profile on the pile maximum kinematic bending moments both for single pile and pile groups. At the pile head, the homogeneous assumption underestimates the pile response, while the opposite effect is found along the pile shaft.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): T. Wichtmann, K. Steller, T. Triantafyllidis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A study on the influence of the sample preparation method on the cumulative strains in sand under high-cyclic loading is presented. Numerous drained cyclic triaxial tests with 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msup〉〈mrow〉〈mn〉10〈/mn〉〈/mrow〉〈mrow〉〈mn〉5〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 cycles were performed on samples prepared by either air pluviation out of a funnel, air pluviation using a multiple sieve apparatus, water pluviation, moist tamping or dry loose deposition with a subsequent compaction by either vibration or tapping. The test results reveal a significant influence of the sample preparation method on the intensity of strain accumulation. While very loose samples prepared by moist tamping show much larger strain accumulation rates than their air-pluviated counterparts at same density, it is the other way around at medium and high densities. Samples prepared by procedures involving compaction in the dry state are more resistant against cumulative effects than samples directly prepared to the same relative density. The differences in the rates of strain accumulation are the result of a different initial fabric generated by the various constitution methods. A micromechanical explanation based on the distribution of contact normal orientations is provided. In contrast, the direction of strain accumulation (cyclic flow rule) and the elastic portion of deformation during the cycles (strain amplitude) are rather insensitive to the choice of the sample preparation method.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Savvas P. Papadopoulos, Anastasios G. Sextos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a novel, bridge-dependent approach for quantifying the increase of design quantities due to spatially variable earthquake ground motion (SVEGM). Contrary to the existing methods for multiple support bridge excitation analysis that are either too complicated to be applied by most practitioners or oversimplied (e.g. Eurocode 8, Annex D provisions), this method aims to strike a balance between simplicity, accuracy and computational efficiency. The method deliberately avoids generating support-dependent, acceleration or displacement, asynchronous inputs for the prediction of bridge response. The reasons behind this decision are twofold: (a) first, the uncertainty associated with the generation of asynchronous motion scenarios, as well as the exact soil properties, stratification and topography is high while, (b) the response of a bridge is particularly sensitive to the above due to the large number of natural modes involved. It is therefore prohibitive to address SVEGM effects deterministically in the framework of a design code. Instead, this new method is based on two important and well-documented observations: (a) that SVEGM is typically 〈em〉globally beneficial〈/em〉 but 〈em〉locally detrimental〈/em〉 [1], and (b) that the local seismic demand increase is very closely correlated with the 〈em〉excitation of higher modes,〈/em〉 which are not normally activated in the case of uniform ground motion [2,3]. Along these lines, a set of static analyses are specified herein to complement the standard, code-based response spectrum analysis. These static analyses apply spatially distributed lateral forces, whose patterns match the shape of potentially excited anti-symmetric modes. The amplitude of those forces is derived as a function of the expected amplification of these modes according to the process initially proposed by Price et al. [4]. Two real bridges with different structural configurations are used as a test-bed to demonstrate the effectiveness of the new method. Comparison of the results with those obtained through rigorous response history analysis using partially correlated, spatially variable, spectrum-compatible input motions [5] shows that, the simplified method presented herein provides a reasonably accurate estimation of the SVEGM impact on the response of the bridges examined at a highly reduced computational cost. This is essentially an elastic method that is found to be simple, yet precise enough to consist an attractive alternative for the design and assessment of long and/or important bridge structures in earthquake-prone regions.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: March 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 130〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Jintai Wang, Sajjad Salam, Ming Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a study of the effects of shaking history on liquefaction and cone penetration resistance of a clean sand by using 1-g shake table and piezo-cone penetration test (CPTu). A uniform liquefiable clean sand specimen was air-pluviated and saturated in a large laminar shear box. The sand specimen was subjected to four shaking events. Piezometers were embedded at different depths to measure the excess pore pressures during and after each event. A series of CPTu tests were conducted on the sand specimen across different shaking events to investigate the effect of shaking history on cone penetration resistance. The main findings of the paper are: 1) the relative density (〈em〉D〈/em〉〈sub〉r〈/sub〉) increased as a result of prior shaking events; increase of liquefaction resistance was observed from Event #1 to Event #4-1, as a result of densification; 2) input motion with an acceleration amplitude of 0.4 g and 25 cycles induced dilatancy of very dense sand specimen and reduced the liquefaction resistance in subsequent shaking events; a mild shaking event with an acceleration amplitude of 0.1 g and 14 cycles was able to erase the disturbance caused by strong shaking, recompact the sand and increase the liquefaction resistance; 3) the post-shaking pore pressures increased with time after shaking had ended; the magnitude of increase was related to 〈em〉D〈/em〉〈sub〉r〈/sub〉 and pore pressure ratio at the end of shaking; 4) liquefaction significantly disturbed the existing soil structure and thus reduced the cone resistance immediately after the shaking; both shaking disturbance and sand densification affected the cone resistance variation before and after shaking.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Iván F. Huergo, Hugo Hernández-Barrios, Carlos M. Patlán〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An equivalent coupled-two-beam (CTB) discrete model is presented to compute the dynamic response in time domain of flexible-base buildings with linear fluid viscous dampers (FVDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allows the consideration of intermediate modes of lateral deformation. The effects of different lateral deformations on the pre-design stage of two high-rise buildings are showed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and three different distribution methods for linear FVDs: uniform-distribution (UD), story-shear-proportional-distribution (SSPD) and story-shear-strain-energy-distribution (SSSED). For UD method, the damping coefficients of FVDs increase as the flexural rigidity of the building decreases; whereas for SSPD and SSSED methods, the damping coefficients of FVDs vary along the height depending on the type of lateral deformation. For the three distribution methods and the same lateral deformation, the damping coefficients of FVDs decrease as the soil flexibility increases, which leads to a significant decrease in controlling earthquake-induced vibrations and wind-induced vibrations in the two high-rise buildings on a soft soil.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Yaser Jafarian, Hamed Javdanian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small-strain dynamic properties of sands are commonly estimated through the correlations basically developed by the experimental results of isotropically consolidated specimens. In reality, however, the in-situ stress state of soils is not necessarily isotropic. Several resonant column tests were conducted on reconstituted samples of a coastal siliceous-carbonate sand in a variety of initial relative density and consolidation stress. The results indicate that despite the noticeable effect of initial stress anisotropy on the values of maximum shear modulus 〈em〉G〈/em〉〈sub〉max〈/sub〉, the values of minimum damping ratio 〈em〉D〈/em〉〈sub〉min〈/sub〉 are almost independent of initial stress ratio. In a preceding paper, the authors proposed a correction factor for two siliceous and calcareous sands which correlates the shear modulus in anisotropic stress condition to the isotropic shear modulus. It is demonstrated herein that the proposed formula is precise for the siliceous-carbonate sand of the present study. The proposed empirical relationship is then compared with a correction factor proposed by others for shear modulus of sands in stress anisotropy condition.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): M. Gao, S.P. Tian, Y. Wang, Q.S. Chen, G.Y. Gao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this Technical Note, a new material (i.e., Duxseal) with high damping ratio is introduced to the wave impeding block (WIB) as an active vibration isolating barrier in the free field. To evaluate the performance of the Duxseal-WIB (DXWIB), a set of field tests are performed at three test sites of Jinan-Qingdao high-speed railway of China subjected to a moving load at a high speed of 250 km/h. Accelerations in the X-, Y-, and Z-directions are monitored at multiple distances away from the track. Characteristics of ground vibrations in both time and frequency domains are analyzed using the test data. The effectiveness of DXWIB in reducing the level of ground vibration is discussed and demonstrated by comparing with the case with traditional WIB.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Jagat Kumar Shrestha, Sujit Bhandari, Suman Pradhan, Dipendra Gautam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Masonry buildings comprise a major fraction of the total buildings globally. Analysis of masonry buildings is challenging due to underlying uncertainties in material properties, variation in construction system, workmanship discrepancies, and analysis schemes. At present, several finite element approaches are available for masonry modeling; however, most of such methods are sophisticated as they require huge computational efforts, time, and realistic allocation of material properties. Thus, there is a need for a simple yet representative method to capture the complex behavior of masonry buildings. To this end, we propose a displacement-based Simplified Frame Model (SFM) to analyze masonry structures. Details of the methodology including the analysis results are presented in this paper. Nonlinear static pushover analysis is adopted for finite element modeling of the prototype building. A comparison between the analytical and experimental results highlights that the SFM can be effectively used for masonry analysis assuring less computational efforts.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Jinghua Zhang, Yong Yuan, Emilio Bilotta, Haitao Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Analytical solutions are deduced for seismic responses of shaft-tunnel junction under longitudinal excitations. The influence of the tunnel is incorporated by introducing terms of shaft-tunnel and soil-tunnel interactions into equations originally developed for rigid caissons. The shaft is simplified into a rigid body. The tunnel is represented by a continuous beam perpendicularly fixed onto the shaft. Firstly, solutions for displacements of the shaft are given. Then, solutions for the three major internal forces of the tunnel are proposed. Validity of the proposed solutions is examined by finite element method in respect of the shaft and the tunnel separately. The comparisons confirm that the proposed solutions could successfully predict the displacements of the shaft and the three major internal forces of the tunnel at the vicinity of the shaft-tunnel junction. However, they become less accurate with increasing distance to the shaft. Interactions among the shaft, the tunnel, and the soil are discussed based on the proposed solutions. A special emphasis is placed on the mutual influences between the shaft and the tunnel. Displacements of the shaft, especially the rotational displacements, are likely to decrease under longitudinal excitations when connected to tunnels. Shaft-soil relative displacement and soil-tunnel relative stiffness are the two key factors affecting the seismic responses of the tunnel. The former determines the amplitudes of the internal forces, while the latter governs how the internal forces distribute along the tunnel axis. A conceptual aseismic measure is studied by setting a pin joint at the shaft-tunnel junction. Theoretically, it could eliminate the influence imposed on the tunnel by the rotational displacement of the shaft.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Grigorios Tsinidis, Luigi Di Sarno, Anastasios Sextos, Peter Furtner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper investigates the efficiency and sufficiency of various seismic intensity measures for the structural assessment of buried steel natural gas (NG) pipelines subjected to axial compression caused by transient seismic ground deformations. The study focuses on buried NG pipelines crossing perpendicularly a vertical geotechnical discontinuity with an abrupt change on the soil properties, where the potential of high compression strain is expected to be increased under seismic wave propagation. A detailed analytical framework is developed for this purpose, which includes a 3D finite element model of the pipe-trench system, to evaluate rigorously the pipe-soil interaction phenomena, and 1D soil response analyses that are employed to determine critical ground deformation patterns at the geotechnical discontinuity, caused by seismic wave propagation. A comprehensive numerical parametric study is conducted by employing the analytical methodology in a number of soil-pipeline configurations, considering salient parameters that control the axial response of buried steel NG pipelines, i.e. diameter, wall thickness and internal pressure of the pipeline, wall imperfections of the pipeline, soil properties and backfill compaction level and friction characteristics of the backfill-pipe interface. Using the peak compression strain of the pipeline as engineering demand parameter and a number of regression analyses relative to the examined seismic intensity measures, it is shown that the peak ground velocity 〈em〉PGV〈/em〉 at ground surface constitutes the optimum intensity measure for the structural assessment of the examined infrastructure.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering〈/p〉 〈p〉Author(s): Giuseppe Oliveto, George D. Manolis〈/p〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Juan P. Villacreses, Bernardo Caicedo, Silvia Caro, Fabricio Yépez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a new procedure for the characterisation of the dynamic mechanical properties of unsaturated fine-grained soils (i.e., dynamic shear modulus and phase angle). The procedure uses a rheometer, which is a conventional device for the characterisation of viscous and viscoelastic materials but with limited used in the area of geotechnical engineering. Tests were carried out on cylindrical samples following a dynamic loading scheme under strain-controlled conditions. This research is divided into two phases. The first phase aims at validating the proposed experimental methodology. Thus, one sample of kaolin was tested using the proposed methodology, and the results were compared against those obtained from the conventional Resonant Column test. During the second phase, samples of kaolin were compacted at the optimum Proctor Standard; conditioned at different degrees of saturation, and tested using the proposed procedure to show its applicability on partially saturated soils. The dynamic shear modulus and phase angle of these samples were measured using a strain level ranging from 6×10〈sup〉-6〈/sup〉 to 1×10〈sup〉-3〈/sup〉 with different suction conditions and without confinement pressure. The results suggest that the newly developed procedure could be more versatile and accurate than available standardized tests.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Guillermo Alexander Riveros, Abouzar Sadrekarimi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microbially induced calcite precipitation (MICP) harnesses the natural metabolic action of bacteria to induce the precipitation of calcium carbonate and alter soil engineering properties. This paper presents the results of using MICP to improve the cyclic resistance of Fraser River sand specimens. The formation of calcite cementation among sand particles is confirmed using scanning electron microscopic images and X-ray compositional analysis of cemented sand clusters. The results show that the velocity of a shear wave (V〈sub〉S〈/sub〉) traveling through the specimen starts to increase just as the calcium solution is introduced into each specimen. Liquefaction resistance of sand samples is subsequently measured in a series of cyclic direct simple shear tests. MICP-treated samples exhibit cyclic resistances of up to 67% higher than those of the untreated sand. Post-liquefaction volumetric strain and changes in cyclic resistance in a repeated cyclic loading are also assessed and compared for the original and the treated sand specimens.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): C.L. Xin, Z.Z. Wang, J. Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The buffer layer around the cross section of lining structure would be the most simple and effective shock absorption measure, which can cut off the transferring paths of adverse effects from surrounding rock to lining structures. Meanwhile, it can reduce the seismic action intensity and minimize the extra pressure from surrounding rock by changing seismic acting patterns. This paper presents outcomes by investigating the interaction between lining structure and surrounding rock during excitation as well as deriving influencing parameters with regard to shock absorption performances of buffer layer. Afterwards, series numerical calculations are systematically carried out with attention given to the seismic-induced deformation responses of rock-layer-lining system. Finally, an elaborated evaluation method for assessing shock absorption performance of buffer layer with an evaluation expression is proposed, which is validated by series shaking table model tests and numerical simulations. This evaluation expression would be able to guide the selection and construction of buffer layer according to the geological conditions and construction circumstances by changing geometric and material parameters. The evaluation result would have uniqueness once all the parameters are confirmed. From this expression and its derivation process, the following findings can be drawn: (1) The cross section of tunnel has the identical particular deformation pattern in each constructing phase during excitation regardless of the existence of lining structure and buffer layer, that is, the two orthogonal diagonal diameters of cross section alternatively expand and contract. (2) The geometric and material parameters simultaneously determine the shock absorption performances of buffer layer, which grows in direct proportion to geometric variables but decreases in inversely proportion to material variables. (3) When the ratio of lining inside radius to buried depth is equal to 0.2 (i.e. 〈em〉r〈/em〉〈sub〉〈em〉0〈/em〉〈/sub〉/〈em〉H〈/em〉 = 0.2), the buried depth of tunnel engineering should be the ideal position for adopting buffer layer. Meanwhile, when the ratio of buffer layer thickness to lining inside radius is equal to 0.2 (i.e. 〈em〉t〈/em〉〈sub〉〈em〉b〈/em〉〈/sub〉/〈em〉r〈/em〉〈sub〉〈em〉0〈/em〉〈/sub〉 = 0.2), it can be confirmed the optimal thickness of buffer layer. (4) The evaluation expression of shock absorption performance is independent of seismic waveforms but involved in the excitation intensities and the destruction states of lining structure.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Yunpeng Zhang, Xiaoyan Yang, Wenbing Wu, M. Hesham El Naggar, Guosheng Jiang, Rongzhu Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Torsional vibrations of pipe pile are more complicated compared to solid pile. In actual engineering, pile surrounding soil may be strengthened or weakened due to different pile installation methods, which is regarded as pile installation effect. At the same time, soil plug effect which describes the interaction between the soil plug and pile wall is also non-negligible in bearing analysis. Along the model of inhomogeneous medium, this paper subdivides the inhomogeneous soil region into certain sub-zones whose shear complex stiffness are derived by virtue of continuity conditions and plain strain model. To study the influence of soil plug effect, the additional mass model is raised and utilized in this paper. In this model, the pile-soil plug system is vertically split into infinite sections, and each pipe pile section and soil plug section is connected by distributed Voigt model. The analytical solution of torsional complex impedance is acquired and compared with results obtained from former studies to verify its rationality. Finally, a parametric research is presented to exhibit the influence of the pile installation and soil plug effect on the torsional complex impedance of pipe pile head.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Weiyun Chen, Dongsheng Jeng, Wei Chen, Guoxing Chen, Hongyi Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The evaluation of dynamic response in a porous seabed has been studied since the 1980s. However, most previous analytical investigations focused on the loading from ocean-wave action. In this paper, an analytical method is presented to study the soil displacements, pore pressures and effective stresses in a nearly saturated porous seabed subjected to earthquake excitation. Based on Biot's theory and the concept of homogeneous pore fluid, a set of analytical solutions for various response are derived in terms of seawater depth, seabed parameters and seismic characteristics of bedrock. Numerical examples are given to demonstrate the significant influences of saturation degree, soil permeability and excitation frequency on the earthquake-induced soil displacement and pore pressure in a nearly saturated seabed. In addition, to investigate the effect of inertia force on the induced response in soils, two common-used formulations, i.e., fully dynamic (FD form) and partly dynamic (PD form), are considered, respectively. The regions of validity for these two formulations are identified and depicted to help engineers to select the appropriate solution for the seismic analysis in coastal engineering practice.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: March 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 130〈/p〉 〈p〉Author(s): Xingbo Pu, Qingjuan Meng, Zhifei Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Periodic structures often fabricated at the micro/nano-scale have opened new vistas in acoustic and electromagnetic wave manipulations due to band-gap properties. This study shows theoretically and experimentally that the propagation of destructive surface waves can also be controlled artificially using periodic wave barriers that modify the global properties of the background soil. To depict the attenuation property of surface waves, this study provides a complete dispersion analysis, the complex dispersion relation. Results show that, remarkably, the attenuation zone for surface waves includes not only the band gap but also other evanescent surface modes. This result agrees well with that in the experimental transmission spectra for both periodic trench barriers and periodic pile barriers. Due to their broadband attenuation performance, periodic wave barriers are expected to apply to vibration isolation in a wide range of systems.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Vikas Sharma, Kazunori Fujisawa, Akira Murakami〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, space–time finite element method is developed for the dynamic fracture analysis of dam–reservoir (DR) system which is supported on a perfectly rigid foundation. In this method, an auxiliary variable 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" altimg="si1.svg"〉〈mi〉q〈/mi〉〈/math〉 representing the first-order time derivative of hydrodynamic pressure is treated as the primary unknown for the reservoir domain. Similarly, velocity 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" altimg="si2.svg"〉〈mi mathvariant="bold"〉v〈/mi〉〈/math〉 is the primary unknown for the solid domain. A three point Gauss–Lobatto quadrature rule is employed for computing time integral of those terms which contain stress term. Further, a partitioned method based on a block-iterative scheme is employed to incorporate the material nonlinearity of the concrete and to enforce the coupling between the two domains in a single iteration loop. A co-axially rotating crack model with exponential strain softening rule is employed to model the fracture of the concrete. Afterwards, numerical performance of the proposed scheme is demonstrated by analyzing two situations of dynamic fracture of Koyna concrete gravity dam.〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Ai-Yun Jin, Jian-Wen Pan, Jin-Ting Wang, Xiu-Li Du〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Milad Kowsari, Tim Sonnemann, Benedikt Halldorsson, Birgir Hrafnkelsson, Jónas Þ. Snæbjörnsson, Sigurjón Jónsson〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Xi Chen, Yunhe Liu, Binpeng Zhou, Dixiong Yang〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Gang Zheng, Wenbin Zhang, Haizuo Zhou, Pengbo Yang〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Yi Luo, Dengxing Qu, Gang Wang, Xinping Li, Guang Zhang〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Zilan Zhong, Yiyao Shen, Mi Zhao, Liyun Li, Xiuli Du, Hong Hao〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Ahmet Kuvat, Erol Sadoglu〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Xun Peng, Zhiqiang Huang, Lei Hao〈/p〉

Beschreibung: 〈p〉Publication date: Available online 6 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering〈/p〉 〈p〉Author(s): Francesco Cavalieri, António A. Correia, Helen Crowley, Rui Pinho〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Benbo Sun, Sherong Zhang, Minjiang Deng, Chao Wang〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Zhijian Wu, Shiming Xu, Dawei Chen, Duoyin Zhao, Dan Zhang〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Ivan Paulmichl, Thomas Furtmüller, Christoph Adam, Dietmar Adam〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Jinghua Zhang, Yong Yuan, Zhen Bao, Haitao Yu, Emilio Bilotta〈/p〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Dimitrios Vamvatsikos, Konstantinos Bakalis, Mohsen Kohrangi, Stella Pyrza, Carlo Andrea Castiglioni, Alper Kanyilmaz, Francesco Morelli, Aurel Stratan, Mario D' Aniello, Luis Calado, Jorge Miguel Proença, Hervé Degee, Benno Hoffmeister, Marius Pinkawa, Pavlos Thanopoulos, Ioannis Vayas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A risk-consistent approach is proposed for the evaluation of behaviour factors that are compatible with Eurocode 8, using nonlinear static and dynamic analysis. It comprises seven discrete steps, involving hazard assessment and record selection at multiple sites, designing and modelling multiple archetype buildings and assessing their performance vis-à-vis target safety objectives. In all cases, uncertainty is incorporated and propagated to the final results whereby a flexible verification procedure is offered to account for the confidence of the investigator on the data available. An example application is offered on steel concentrically braced frames, highlighting the need for selecting appropriate performance targets for Europe. The overall added value goes beyond the current state of art, offering a consistent risk basis for the seismic design of different systems that is compatible with current uniform hazard design spectra and can benefit from future risk-targeted hazard maps.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Yu Huang, Xi Xu, Junjia Liu, Wuwei Mao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pile-anchor structures are now widely used in major slope reinforcement projects, but research on the seismic response of slopes reinforced by these structures has been very limited. This paper presents the results of a series of 50〈em〉g〈/em〉 dynamic centrifuge tests that reproduce the seismic response of a slope reinforced by a pile-anchor structure exposed to an earthquake-induced stress field. A silica gel model of a slope is used to conduct multiple tests. Long-period wave amplitude amplification and frequency filtering are observed after spectral analysis. Pile bending moments and anchor tensions were recorded before the earthquake, at the moment of peak ground acceleration, and after the earthquake and the data show that the pile is the main load-bearing structure. The anchor aids in keeping the pile from tilting outward to improve the durability of the pile. Pile-anchor structure failure is caused by anchor relaxation, pile bending, and slope displacement after the passage of multiple seismic waves. A suggestion for pile-anchor structure design is provided. This paper provides a useful reference for future research on the interactions between support structures and a slope during and after earthquakes. The conclusions provided by these tests lay the foundation for designing pile-anchor reinforcement structures for better dynamic performance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Filomena de Silva〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Joint analysis of hazard and fragility is becoming a widespread and unavoidable tool to estimate losses caused by earthquakes. The application of such analysis to buildings on soft soil is improved when the dynamic soil - foundation - structure interaction is considered, since both the reference hazard on site and the structural performance are modified by soil compliance. This study investigates and compares the site-specific seismic demand required to squat or slender masonry towers settled on stiff or soft soil. To this aim, 96 non-linear dynamic analyses were performed on 3D models, including soil, foundation and structure and excited by fourteen unscaled records of real earthquakes. Distributions of the equivalent bending rotation of structure and of peak and residual rotations of foundation were calibrated on numerical results and convoluted with the hazard curves of three Italian cities, to compute the mean annual rate of exceeding different values of structural and foundation demand. The resulting curves highlight that soil deformability enhances the bending demand and produces a not negligible permanent tilt in towers.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Diyuan Li, Feihong Gao, Zhenyu Han, Quanqi Zhu〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Luis A. Pinzón, Yeudy F. Vargas-Alzate, Luis G. Pujades, Sergio A. Diaz〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Abbas Ghalandarzadeh, Salman Rahimi, Ali Kavand〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Silvano Erlicher, Olivier Lherminier, Miquel Huguet〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): Zhi Yong Ai, Chang Jie Xu, Yong Zhi Zhao, Chun Lin Liu, Guang Peng Ren〈/p〉

Beschreibung: 〈p〉Publication date: May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 132〈/p〉 〈p〉Author(s): P. Ndy Von Kluge, G. Djuidjé Kenmoé, T.C. Kofané〈/p〉

Beschreibung: 〈p〉Publication date: Available online 10 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering〈/p〉 〈p〉Author(s): Arman Ghaemi, Jean-Marie Konrad〈/p〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Omar S. Qaftan, Tahsin Toma-Sabbagh, Laurence Weekes, Levingshan Augusthus-Nelson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Validated numerical approaches are very important in dynamic studies of soil-structure interaction. Experimental outputs of physical models are required to validate the numerical approaches. Testing and analysis of an experimental scaled model is economical in comparison with investigating real size structures. However, a set of scale factors are required to model a full-scale structure accurately as a scaled model in a laboratory environment. In this paper, the scaling procedure and design of a scaled multi-storey concrete wall-frame structure with a scale factor of 1:50 are addressed. A specially selected dry sand with round shaped particles and specific grain size distribution was adopted in this study. A flexible soil container was designed and built to represent the soil boundary behaviour during time-history seismic excitations. The experimental investigations were divided into three different stages: fixed based structure without soil interaction; soil container without any structure; and, a structure with raft and pile foundations in the soil container. Finally, the same experimental stages were modelled numerically using a 3D finite element software. The results showed that the finite element simulations produced a good response when compared with the experimental results and these numerical models are suitable to be employed for further dynamic studies.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Pampa Dey, Vinay K. Gupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the areas of high seismicity, where several medium-to-strong events may occur before the design event, the cumulative damage due to earthquake events expected during the design life of the structure should be kept within safe limits. This may be achieved by raising the design force level corresponding to the largest seismic event anticipated during the design life of the structure by a factor known as Design Force Ratio (DFR). This study is an attempt to generalize the existing DFR spectrum by modifying how the damage during an event is computed and how the power spectral density function (PSDF) of the ground motion process for that event is estimated. As the existing models do not estimate incremental damage during an event of a sequence, the modified Park-Ang damage model is proposed to be modified further such that its estimates for the individual events add up to the cumulative damage index for the entire sequence as well as the effects of residual displacements are accounted for. The proposed model can estimate additional damage due to an event (in a multiple-event situation) without requiring the excitation time-history. The generalized procedure for DFR spectrum is based on using this model and the concept of spectrum-compatible PSDF. A numerical study on a hypothetical seismic environment shows that the DFR spectrum is very sensitive to the directions of the residual displacements and that all residual displacements should be assumed in the same direction for a conservative estimate of the DFR spectrum. It is also shown that in that case, the event with maximum damage potential should be assumed to occur as the last event in the sequence in order to maximize the cumulative damage.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Nikolaos Ntritsos, Misko Cubrinovski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉There is a growing awareness of the need for the earthquake engineering practice to incorporate in addition to empirical approaches in evaluation of liquefaction hazards advanced methods which can more realistically represent soil behaviour during earthquakes. Currently, this implementation is hindered by a number of challenges mainly associated with the amount of data and user-experience required for such advanced methods. In this paper, we present key steps of an advanced seismic effective-stress analysis procedure, which on the one hand can be fully automated and, on the other hand, requires no additional input (at least for preliminary applications) compared to simplified cone penetration test (CPT)-based liquefaction procedures. In this way, effective-stress analysis can be routinely applied for quick, yet more robust estimations of liquefaction hazards, in a similar fashion to the simplified procedures. Important insights regarding the dynamic interactions in liquefying soils and the actual system response of a deposit can be gained from such analyses, as illustrated with the application to two sites from Christchurch, New Zealand.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Soil Dynamics and Earthquake Engineering, Volume 131〈/p〉 〈p〉Author(s): Junjun Guo, M. Shahria Alam, Jingquan Wang, Shuai Li, Wancheng Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Seismic intensity measures (IMs) play an important role in predicting the seismic responses of structures subjected to strong earthquakes. This paper proposes a general procedure to identify the optimal IMs for a long span cable-stayed bridge subjected to far-field and near-fault ground motions based on generalized linear regression models. Firstly, the generalized linear regression models, such as ordinary least squares (OLS), ridge regression and Lasso regression are presented. Secondly, the three dimensional numerical model of the bridge is generated in the OpenSees platform. Thirdly, 22 IMs are considered, and 160 ground motions from four site conditions are selected to excite the bridge in longitudinal and transverse directions separately. Then, the optimal IMs are determined by Lasso regression, which is an extended version of OLS, and the quadratic polynomial regression model is adopted to establish the probabilistic seismic demand models of the bridge. The numerical results reveal that peak ground velocity (PGV) can be selected as the optimal IM if only one IM is considered in the seismic demand models. However, PGV has a poor predictive ability for the seismic responses in the transverse direction. Hence, PGV, peak ground displacement (PGD), root-mean-square of velocity (V〈sub〉RMS〈/sub〉), specific energy density (SED), velocity spectrum intensity (VSI) and Fajfar intensity (FI) are selected as the optimal IMs by Lasso regression, and they are correlated with velocity except for PGD. The identified six IMs together can significantly increase the fitting ability of the models.〈/p〉〈/div〉 〈/div〉