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Fault dislocations may lead to permanent ground rupture displacements, causing significant damage to bridges spanning fault lines. Accurate prediction of permanent displacement due to fault dislocations is essential for assessing the seismic resilience of bridges across faults. This study introduces a highly precise BPNN (Backpropagation Neural Network)-based model for predicting permanent fault rupture displacements at the ground surface. The model produces artificial ground motion, known as 'fault-crossing ground motion', through the integration of low-frequency (LF) and high-frequency (HF) components. The research centers on a 538-m long-span steel truss suspension bridge, employing a comprehensive finite element (FE) model developed with ABAQUS software. The study methodically investigates the impact of permanent fault rupture displacement, fault-crossing effects, and angles on the seismic behavior of the suspension bridge. Research findings indicate that the BPNN-based approach precisely predicts permanent fault rupture displacements due to fault movements. The position of the fault line relative to the bridge, along with the fault-crossing angle and permanent fault rupture displacement, significantly influences the bridge's seismic responses. Notably, as permanent fault rupture displacements increase, the magnitudes of dynamic responses vary considerably. Longitudinally, the amplification of displacement, shear force, and moment in the towers is more pronounced than transversely. Furthermore, a gradual increase in shear force at the tower base poses a significant risk of shear failure. LF components predominantly determine the requirements for internal forces and displacements. This study presents a direct and dependable method for artificially synthesizing ground motion for the seismic analysis of fault-crossing suspension bridges, underscoring the influence of fault-crossing angles and locations on seismic responses. • The model for predicting ground rupture dislocation based on BPNN is proposed. • The proposed model is used to generate fault-crossing ground motion by a superposition method. • The FE model of a suspension bridge is established and parameter analyses are performed. • Recommendations for the seismic design of suspension bridges subjected to faulting are drawn. [ABSTRACT FROM AUTHOR]

On February 6th, 2023, southeastern Türkiye was shaken by two catastrophic earthquakes, close to northwestern Syrian border. The first earthquake (Pazarcık) occurred 45 km west of Gaziantep at 1:17:32 (UTC), with a shallow strike-slip faulting at a depth of approximately 8.6 km and a moment magnitude (M W) of around 7.7. The second event (Elbistan) took place 9 h later, 66 km north-east of Kahramanmaraş city center, also with shallow strike-slip faulting at a depth approximately 7 km and an M W of around 7.6. Turkish authorities reported a death toll of over 59,000 in Türkiye and about 8500 in Syria. The destructive effect of the earthquake resulted from widespread strong ground shaking, a rupture length exceeding 300 km, causing collapse of a large number of buildings. The catastrophic destruction of the built environment was accompanied by a range of other earthquake-related effects, including fault ruptures, landslides, and soil liquefaction. The aim of the study is to analyze the distribution of ground motion and their relationships with the observed damages for the two events. Spectral accelerations of key importance were assessed across a large area in the southeastern part of Türkiye. Notably, these accelerations were generally much higher than existing design spectra. A significant correlation between the observed concentration of damage and the significant amplification of motion induced by local soil conditions (such as soft soils and valley effects). The distinct tectonic structure of the region could be the main reason for the high amplification in the valleys (associated with basin effects), even at large distances from the epicenter, especially in correspondence with the bidimensional graben-type geological structures. The investigation delved into the analysis of four specific regions in detail: Antakya and Hassa (both in the Hatay province), Kahramanmaraş and Göksun. Notably, the observable valley effects were found to play a significant role and could account for the significant damage observed in these regions. • An accurate analysis was conducted to examine the distribution of ground motion for the Türkiye Mw 7.7 Pazarcık and Mw 7.6 Elbistan earthquakes of February 6th, 2023 for a large area in the southeastern part of Türkiye.. • The recorded accelerations were generally much higher than existing design spectra by explaining the extensive devastation in the affected areas. • The observed concentration of damage was found to correlate with the significant amplification of motion induced by local soil conditions, such as soft soils and valley effects. • Detailed studies on four case histories: Antakya, Hassa, Göksun, and Kahramanmaraş, were performed by cross-checking recorded ground motions and geological and geotechnical data. • The analyzed four cities: Antakya, Hassa, Göksun, and Kahramanmaraş settled on relatively thick alluviums bordered by mountainous rock flanks are susceptible to valley effects. [ABSTRACT FROM AUTHOR]

Fault rupture propagation through near-surface soil deposits and the anticipated damage on adjacent structures have been thoroughly investigated focusing on single fault rupture. Nevertheless, large secondary faults have also been observed in field investigations. For this reason, the development of contemporaneous fault ruptures -and the resulting soil displacements-caused by complex combinations of oblique-slip main and non-parallel secondary faults is investigated herein. Moreover, the response of buried steel pipelines crossing such geohazardous areas is also examined aiming to assess pipeline vulnerability due to the presence of secondary faults. The investigation is conducted utilizing a decoupled numerical methodology, in which soil displacements are calculated utilizing a 3D numerical model, and subsequently, they are applied to a separate numerical model for the assessment of pipeline distress. Useful conclusions are drawn regarding the developed fault rupture patterns and the sequent pipeline distress under such detrimental conditions that may occur in seismotectonic regions. [Display omitted] • The complex phenomenon of simultaneous oblique-slip fault ruptures is investigated. • Dip and pitch angles of oblique main and secondary faults are correlated. • For large fault dislocations rupture patterns merge creating multiple curved planes. • Pipelines aligned parallel to a main fault may be subjected to secondary faulting. • Pipelines crossing the fault intersection zone can experience significant distress. [ABSTRACT FROM AUTHOR]

The performance of a Metallurgical Facility located on the Dörtyol-Hatay coast is investigated from seismic soil liquefaction engineering perspective. The facility was shaken by the M7.8, and M7.6 Pazarcık and Ekinözü-Elbistan Kahramanmaraş earthquake sequence. This paper presents the assessment results of soil liquefaction triggering and induced ground deformations at the site. It discusses: i) the seismic response of the facility, more specifically, the surface manifestation of seismic soil liquefaction in the form of soil ejecta, ground deformations and displacements, mapped after the earthquake sequence, ii) the results of site investigation studies, performed prior to the events, iii) subsurface soil characterization of the site, iv) assessments of soil liquefaction triggering, v) analyses of liquefaction-induced ground settlements, lateral deformations and displacements, and vi) comparisons of them with those of the predicted. The case history performance documented herein, and the assessment results are believed to be useful in the development of case history-based predictive models for the assessment of liquefaction triggering and post-liquefaction ground deformations. • Liquefaction manifestations observed in a Metallurgical Facility in Hatay. • Lateral displacements and settlements varied in the range of 5–31 cm and 5–88 cm. • Low plasticity silts and clays were predicted to be liquefied. • Volumetric settlements were predicted by Shamoto et al. (1998) and Cetin et al. (2009). • Lateral displacements were predicted by Hamada et al. (1986) and Youd et al. (2002). [ABSTRACT FROM AUTHOR]

Assessing the built environment's seismic risk relies increasingly on numerical simulations of the response of infrastructure components to seismic motion. Since forecasting earthquake-induced motion is difficult, if not impossible, subjecting the infrastructure to seismic motion from past earthquakes remains the most potent way to assess the infrastructure's risk and resilience. However, such simulations require a rupture-to-rafters modeling approach that entails complex inversion procedures and ultra-scale computations. In this work, we discuss a systematic methodology that attempts to reconstruct the earthquake-induced wavefield only within the near-surface deposits, using ground surface recordings of seismic motion. The methodology improves on alternative approaches by bypassing the need for either seismic source inversion or joint seismic-source-and-material-model inversion, relying instead on a priori knowledge of the soil properties for only the near-surface deposits, thus realizing significant computational savings. The methodology takes advantage of a state-of-the-art, near-surface, seismic wave motion simulation framework rooted in the Domain Reduction Method (DRM), which relies on a reduced computational domain containing the near-surface deposits only, including possible topographic features and even accounting for materially-nonlinear response. The reduced domain is surrounded by an artificial boundary – the DRM boundary –, onto which the seismic input is typically prescribed in forward seismic motion simulations. A narrow wave-absorbing buffer exterior to the DRM boundary completes the computational domain. It is the aim of this work to reconstruct the DRM seismic input from ground-surface records using an inversion approach rooted in partial differential equation (PDE)-constrained optimization, without having to appeal to fault rupture inversion or joint inversions. To this end, we use the DRM, enhanced with a Complex-Frequency-Shifted (CFS) Perfectly-Matched-Layer (PML), to address the forward wave simulation, and an adjoint approach to address the inversion of the DRM seismic input. Our numerical experiments demonstrate the versatility of the methodology in reconstructing the near-surface seismic motion from sparse surface motion records, almost irrespective of the azimuthal coherency of the incoming motion. • The total seismic wavefield is reconstructed in sites affected by seismic events. • Wavefield reconstruction based on sparse ground-surface sensor data. • Seismic force inversion with no a priori knowledge of the seismic source. • Wavefield reconstruction in heterogeneous deposits. • Seismic force inversion for incident motion of arbitrary content and incoherence. [ABSTRACT FROM AUTHOR]

The seismic response and isolation mechanism of a new unconnected pile-caisson foundation (UPCF) suitable for supporting deep-water large-span bridges under seismic loading were investigated by large shaking table tests. Five scaled models were constructed utilizing different cushion material (aggregate), cushion thickness and piles configuration. Each model was tested under 18 different seismic loading conditions. The tests observations were analyzed to evaluate the seismic response characteristics and isolation mechanism of UPCF. The maximum displacement of UPCF and the peak acceleration of the input ground motion were linearly related. Under strong ground motions, the foundation soil and cushion displayed a significant softening behavior manifested in reduced natural frequencies and prolonged periods, which resulted in lower acceleration amplification. However, the stiffnesses of soil and cushion were largely restored after the ground shaking ended. The cushion model with larger aggregate particles performed better in terms of the caisson residual displacement and displacement restoration rate of the caisson. It was found that the UPCF constructed with a thin cushion layer comprised of large, rounded aggregate particles exhibited acceptable seismic isolation effect and reduced the peak seismic acceleration by up to 26.7%. It was also observed that the front and middle piles experienced larger loads, and accordingly, their peak moment envelopes were greater and the location of peak moment was shallower. • The dynamic response of the unconnected piles-caisson foundation (UPCF) is obtained, by large-scale shaking table tests. • The influences of cushion material, thickness and pile arrangement on the isolation effect are evaluated. • It is observed that the softening effect of the cushion under strong earthquake motions. • The relationship between earthquake intensity and caisson peak displacement is obtained. [ABSTRACT FROM AUTHOR]

During seismic events, slopes buttressed by anchored piles can experience instability when piles convert to perilous cantilever systems upon anchor cables failure. Implementing buffer devices in anchoring structures has the potential to reduce the seismic forces in the anchors and consequently improve the seismic performance of the supported structures. Taking advantage of the excellent ductility of flexible piles, this study investigates a buffer device installed in series with the anchored piles. Shaking table tests were conducted on a slope stabilized by buffer-equipped anchored piles considering two typical pile tip conditions: either hinged or free end restraints. Three ground motions with different characteristics were applied to the model slopes fitted with springs with varying stiffness and its seismic response was evaluated in terms of soil accelerations, pile displacements, earth pressures, and anchor-cable forces. In addition, the cable loading reduction mechanism was investigated through the force Fourier spectrum. The results indicated that the system dominant frequency decreased for anchor with hinge support and the pile displacement increased and the dynamic earth pressure decreased as the spring stiffness decreased. Most importantly, implementing the buffer device (i.e., the spring) reduced the response energy significantly over the whole frequency range, especially in the middle range, which resulted in a marked reduction in the anchor cable stress and fatigue damage. The reduction of anchor force was found to be inversely correlated with the spring stiffness. Based on the maximum pile displacement and spring stroke, a stiffness optimization strategy was proposed considering the foundation conditions and seismic excitations. For major earthquakes, stiff springs are advisable to mitigate load effects and to help maintain pile displacement within permissible bounds, while the spring stiffness can be reduced appropriately by implementing a hinge support. Meanwhile, the design should focus on critical displacement rather than loading reduction for seismic hazard characterized by near field earthquakes or high peak ground acceleration. • Enhancing Seismic Performance of Anchored Piles with Innovative Buffer Devices. • Investigating the Influence of Spring Stiffness and Foundation Form on Structural Seismic Response. • Unraveling the Mechanism of Dynamic Anchor-Cable Force Reduction and Load-Reduction. • Optimal Spring Stiffness for Seismic Resilience Considering Foundation Conditions and Seismic Excitations. [ABSTRACT FROM AUTHOR]

Although permanent ground movement can cause devasting damages to the infrastructures, contributions assessing the effect of faulting on earth dams are limited with no notable experimental outcomes. This paper aims to provide conceptual information by investigating the response of earth dams with a clayey core subjected to reverse fault rupture using centrifuge experiments. The influence of the earth dam's location on the fault tip and the effect of alluvial foundation thickness beneath the dam was addressed by eight centrifuge tests at 60-g centrifugal acceleration. One model also explored the fault rupture-earth dam interaction considering a soil-cement cut-off wall beneath the center of the core. Distortion, sliding, and rotation of cores were observed as consequences of reverse faulting depending on the point of intersection between the dam body and fault trace. An increase in the core deformation was also captured for dams on thinner foundation layers. The freeboard height of the dam also decreases by 48%–90% of the vertical fault throw and should be considered in the design phase to avoid overtopping. • Centrifuge tests are conducted for evaluating fault rupturing through the earth dams. • Effects of fault location and alluvial foundation layer on the response of dams were investigated. • No transverse cracks were observed in cores due to the faulting. • Bending, sliding, and vertical movement of cores were captured in different vertical fault throws. • The freeboard height of the dam also decreases by 48%–90% of the vertical fault throw. [ABSTRACT FROM AUTHOR]

The purpose of the present paper is to investigate the effects of a normal fault rupture propagation towards a highway embankment founded on a single-layered soil. To achieve this, quasi-static parametric numerical analyses are performed with the 2D finite difference code, FLAC. The work addresses the influence of the embankment's presence on the fault rupture path, as well as, the deformation of the embankment and the alteration of its initial compaction degree due to the rupture propagation. Results of numerical analyses indicate that the presence of embankment significantly affects the deformations of ground surface. In addition, it is observed that spread of normal fault rupture through the examined embankment causes substantial deformations of embankment's external surface and significant drop of relative compaction. This work achieves to map and quantify the damage of the embankment and therefore provides substantial information on its functionality and safety. • Normal fault rupture diffusion through an embankment based on a single-layered soil. • Effect of embankment's presence on rupture path and soil's free surface distortion. • Important deformation of embankment's external surface due to rupture propagation. • Quantification and mapping of damage pattern of the embankment. • Reduction of embankment's initial compaction degree due to rupture propagation. [ABSTRACT FROM AUTHOR]

Abstract In the present work, the impact of reverse fault rupture propagation through a highway embankment founded on a single-layered soil is investigated. The investigation takes place by means of quasi-static parametric numerical analyses using a 2D finite difference software (FLAC). The effect of the embankment's existence on fault rupture pattern, as well as, the influence of rupture spread at the embankment's integrity, are thoroughly examined. Moreover, two criteria based on the effect of rupture propagation on embankment's initial compaction degree and volume modification are suggested for mapping and quantification of embankment's damage due to rupture diffusion. Based on those results, it becomes evident that the embankment's presence affects the distortion of soil surface. Significant distortion on embankment's external surface and considerable reduction of its initial compaction degree are detected. Highlights • Reverse fault rupture spread via an embankment founded on a single-layered soil. • Influence of reverse fault rupture outcropping path by embankment's presence. • Significant distortions of embankment's external surface due to rupture spread. • Mapping and quantification of embankment's damage due to rupture propagation. • Rupture spread causes drop of embankment's initial relative compaction. [ABSTRACT FROM AUTHOR]

Abstract Several earthquakes over the past two decades have demonstrated that bridges crossing fault rupture zones may suffer significant damage due to the combined effects of ground shaking and surface rupture. Although it is widely recommended to avoid building a bridge across a fault, it is not always possible to achieve this objective, especially in regions with a dense network of active faults. This review begins by compiling two databases: one of fault-crossing bridges damaged in past earthquakes and another of bridges crossing potentially active fault rupture zones. The article then continues to review findings of experimental, analytical and numerical studies, and to summarize seismic design provisions and recommendations related to fault-crossing bridges. The review ends with suggestions for future research directions in this area. Highlights • Information about fault-crossing bridges damaged in past earthquakes is collected. • A database of well-documented cases of bridges crossing potentially active faults is compiled. • Small- and large-scale experimental studies of fault-crossing bridges are reviewed. • Analytical and numerical studies of bridges crossing fault rupture zones are summarized. • Seismic design provisions and recommendations for fault-crossing bridges are discussed. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a description of testing procedure and results of the LEAP-GWU-2015, and an investigation of the effect of the radial gravity field in centrifuge modelling. Dynamic responses of two models are compared. One had a planar surface with a 5° slope relative to the base of the container; the other had a curved surface to maintain a constant slope angle with respect to the radial g-field. For the centrifuge tests employed in this study, the slope and base excitation are in the tangential direction to spinning centrifuge. Results show that spikes in acceleration records due to cyclic mobility associated with lateral displacements appeared on both models. However, for the plane surface model, acceleration spikes in the negative (upslope) direction are more prominent and the residual downslope ground deformation was larger. Larger lateral displacement was observed in the plane model, while surface displacements in the curved model are smaller and uniform along the length of the model. For the plane model, the radial gravity acting near the slope top is almost constant and gradually increases towards the slope toe which causes a net increase in effective slope angle. Through the comparison the importance of curving the model ground surface is recognized as leading to uniform lateral displacements along the length of the model surface. Highlights • Under the LEAP-GWU-2015, a physical model test under specified conditions is conducted. • Dynamic responses of a saturated sloping ground forming either curved or plane surface are compared. • Larger upslope acceleration and residual deformation was observed in the plane surface model. • In the curved model, displacements were smaller and uniform along the length of the model. • For centrifuge modelling, importance of curving the model ground surface was by the comparison. [ABSTRACT FROM AUTHOR]

An active sequence of earthquakes (foreshock, main-shock, and aftershocks) hit the Kumamoto area (Japan) in April 2016, resulting in 69 deaths and considerable economic loss. The earthquakes induced numerous ground failures and cascading geo-hazards, causing major damage to important infrastructures. The main damage patterns include: (a) surface rupture with widespread subsidence of the surface ground, resulting in damage and disruption to transport infrastructure; (b) landslide and slope failure of mountains causing severe damage, collapse and near-collapse of bridges; and (c) liquefaction in some areas of Kumamoto City. Following the earthquakes, field surveys were conducted to study the damages and to understand the main cause of the observed failures. This technical note provides a summary of the geotechnical and infrastructural damage in Kumamoto and the lessons learnt and future research needs are also highlighted. [ABSTRACT FROM AUTHOR]

Onshore buried steel pipelines are vulnerable to fault rupture, where large ground displacements are imposed on the crossing pipe and thus protection measures are often necessary to avoid failure. A three-step methodology based on the framework of performance-based earthquake engineering is presented on assessing the effectiveness of protection measures against the consequences of strike-slip faulting on pipes. Firstly, the randomness of the fault movement is quantified, next the pipeline mechanical behavior is numerically assessed and finally the results are combined to extract the strain hazard curves, which are easy-to-handle engineering decision making tools. The various protection measures used in engineering practice or proposed in the literature are evaluated through the mean annual rate of exceeding strain values, also including a simple safety checking format at the strain level. Conclusions are extracted from the proposed assessment methodology on the efficiency of measures with reference to engineering practice and safety requirements of the pipeline operator. [ABSTRACT FROM AUTHOR]

The focus of this paper is to evaluate the seismic response of a cable-stayed bridge built in fault zones considering soil-structure interaction (SSI) effects. Bridges crossing fault-rupture zones may be built in the Forward Region (FR), Middle Region (MR) and Backward Region (BR) relative to the possible position of the fault. Three groups of ground motions (51 records in two orthogonal directions) in above regions are selected as the input from the 1999 Taiwan Chi-Chi earthquake based on the sites relative to the fault rupture. The Sutong Cable-stayed Bridge (SCB) is taken as an example. Two models are used in this study, i.e. the fixed-base bridge and the bridge with SSI effects where four different orientation angles (0°, 30°, 60°, and 90°) have been considered compared to the fault direction. Systematic lumped-parameter models are utilized to represent the dynamic behavior of the foundation supported on soil. The results reveal that the seismic behavior of the SCB in those 3 regions shows significant differences. The SSI effects affect the bridge response through a systematic decrease of all modal frequencies and a substantial change in nature of dominant shapes especially for the higher modes of vibrations. The displacement of such bridges may be underestimated if the SSI effects are ignored. The orientation of the bridge axis relative to fault trace influences the seismic responses of the bridges in fault regions. The bridge located in MR experiences larger responses than that in FR and BR. Due to the high values of velocity spectra, velocity-related intensity measures i.e. peak ground velocity (PGV) and the ratio of PGV to peak ground acceleration (PGA) show strong correlation with the seismic responses of the bridge located in FR. Since the records in MR and BR have high acceleration spectra, PGV and PGA correlate well with the responses of the bridge located in MR and BR. [ABSTRACT FROM AUTHOR]

Tectonic ground deformations in the near-fault region cause major damage to buildings and infrastructure. To characterize ground deformation demands on structures, a novel stochastic approach to evaluate the ground deformations of tectonic origin is developed by combining probabilistic models of earthquake source parameters, synthetic earthquake slip models, and Okada equations for calculating the deformation field due to a fault movement. The output of the method is the probability distribution of ground deformations at a single location or differential ground deformations between two locations. The derived probabilistic models can be employed as input to advanced structural models and analyses. The method is illustrated for the 16 April 2016 Kumamoto earthquake in Japan. By comparing simulated ground deformations with observed deformations at multiple sites, a set of refined source models is first derived and then used to investigate the detailed earthquake characteristics of the event and to develop probability distributions of tectonic ground deformations at target sites. [ABSTRACT FROM AUTHOR]

The near-surface travel-time averaged shear-wave velocity to 30 m ( Vs (30)) is a key parameter for ground-motion prediction equations and building codes. In many cases, however, shear-wave velocity profiles do not extend to 30 m. In this article, we propose an alternative method for estimating Vs (30) from a shallow shear-wave velocity profile, using the travel-time averaged shear-wave velocities at two different depths ( Vs ( z 1 ) and Vs ( z 2 ), and z 1 < z 2 <30 m). Using the data from 643 boreholes from the KiK-net in Japan and 135 boreholes from California where the shear-wave velocity profile reaches at least 30 m, the reliability of the proposed method is validated by the correlations between the measured and the estimated Vs (30) and the accuracy of site classification using the estimated Vs (30). The results show that the proposed method can estimate Vs (30) with high accuracy, as the Pearson correlation coefficients between the measured and the estimated V s(30) are greater than 0.99, and the site classification successful rates using the estimated Vs (30) are greater than 94%, whereas z 1 ≥10 m and z 2 ≥20 m. Compared with the method of Wang and Wang (2015), the proposed method has a certain improvement in the accuracy, with higher correlations and accuracy of site classification. [ABSTRACT FROM AUTHOR]

A new algorithm is proposed to implement viscoelastic wave propagation in earth medium with surface topography by introducing history variables into integral type GZB constitutive equations and by using the recursive formulae of these history variables. Combining the proposed algorithm with the flexural wave algorithm for frame structure and the algorithm for bidirectional wave propagation, a new type of integrated method is developed for earthquake response analyses of near-fault building clusters in mountain city due to rupture of causative fault. The earthquake responses of building clusters of frame structures situated at different sites of a mountain in Chongqing city, China, are studied during a hypothetical M w 6.2 near-fault earthquake. The numerical results show that, for the multi-story buildings, the maximum peak value of beam-end bending moments appears in the building on the hill top and the earthquake risk positions are mainly at the bottom and/or the top of the buildings. For the high-rise buildings, the maximum peak value of beam-end bending moments appears in the building on the mountainside and the earthquake risk positions are mainly at the bottom and/or the middle of the buildings. [ABSTRACT FROM AUTHOR]

Recent earthquakes leading to the emergence of surface fault rupture (SFR) on the ground surface have indicated disastrous damage to buildings. As avoidance is not always possible, proposing mitigation strategies have become quite popular with geotechnical engineers. Given that the performance benefits of helical piles outweigh other piles, the present study investigates the possibility of using cushioned helical-piled raft systems close to active normal faults to mitigate fault-induced deformations. An experimentally validated finite element code considering the critical state of the sand is implemented in this study. The response of cushioned helical-piled raft system to different distances of the raft of the system from the SFR is studied comprehensively, and the results are compared with a cushioned pipe-piled raft system with the same ultimate bearing capacity. The results reveal the superiority of using cushioned helical-piled raft systems in the vicinity of an active normal fault in terms of reducing raft rotation up to nine times, as well as lower values of the fault-induced structural response of the piles. Also, a parametric study on the geometrical aspect of helical piles shows that fault-induced angular rotation of the raft is highly dependent on it. • The cushioned helical-piled raft system reduces the angular rotation of the raft considerably. • The proposed system reduces the structural response of the piles. • s/B is the dominant factor in the failure mechanism of the system. • Geometrical features of helical piles can alter the response of the system significantly. [ABSTRACT FROM AUTHOR]

The geology of SW-Iceland is characterized by alternating basaltic lava units, hyaloclastite formations, postglacial sedimentary filled valleys and alluvial plains, as well as highly fractured bedrock within the Reykjanes Peninsula volcanic rift zone and the South-Iceland transform fault system. Historic earthquakes within this region reach magnitudes 6.5–7. Using earthquake and ambient noise recordings from 15 seismic stations within the rift and transform zones we compared wavefield polarization and seismic site response in order to assess characteristics of local amplification of ground motion. Ambient noise and earthquake ground motion spectral ratios are comparable in frequency and can qualitatively be subdivided into three groups: one with a spectral ratio characterized by a single predominant frequency of horizontal amplification, one with a bi- or multimodal and one characterized by a relatively constant amplitude across the frequency range. Seismic wavefield polarization within the transform zone has a prevailing direction of amplification towards 110°−150°N in the frequency range 1.0–3.0 Hz, having a quasi -perpendicular relationship with mapped faults and fractures. Shear wave splitting results show that the wavefield polarization and fast S wave directions tend to be orthogonal, i.e. highly dependent on the anisotropy of the medium. [ABSTRACT FROM AUTHOR]

High-pass filtering not only removes the low-frequency noise from the near-fault ground motion records, but also eliminates the permanent ground displacement and reduces the dynamic ground displacement. This may considerably influence the calculated seismic response of a spatially extended engineering structure crossing a fault rupture zone. To demonstrate the importance of incorporating permanent ground displacements in the analysis and design of extended structures under specific fault crossing conditions, the dynamic response of a seismically isolated bridge located in the vicinity of a surface fault rupture (“Case A”) or crossing a fault rupture zone (“Case B”) is calculated by utilizing a near-fault ground motion record processed with and without a displacement offset. The seismically isolated bridge considered in this study is a 10-span continuous structure supported by 11 piers, resembling a typical segment of the 2.3 km long Bolu Viaduct 1 located in west-central Turkey. The Lucerne Valley record from the 1992 M w 7.2 Landers earthquake, which preserves a permanent ground displacement in the fault-parallel direction and exhibits a large velocity pulse in the fault-normal direction, is used as the basis for investigating the effect of high-pass filtering on the dynamic response of the bridge. For the seismically isolated bridge located in the vicinity of the surface fault rupture (“Case A”), the utilization of the high-pass filtered ground motion leads to underestimating the demands of pier top, pier bottom and deck displacements. However, the demands of isolation displacement, isolation permanent displacement and pier drift are almost identical for both the unfiltered and filtered versions of the ground motion record. On the other hand, for the seismically isolated bridge traversed by a fault rupture zone (“Case B”), all response quantities are significantly underestimated when the high-pass filtered ground motion is used. These results, though limited to a single bridge structure and a single ground motion input, clearly indicate the importance of permanent ground displacement on the dynamic response of spatially extended engineering structures crossing fault rupture zones. [ABSTRACT FROM AUTHOR]

Buried steel pipelines transport large amounts of fuel over long distances and inevitably cross active tectonic seismic faults when seismic areas are traversed. Eventual fault activation leads to large imposed displacements on the pipeline, which may then fail due to local wall buckling or tensile weld fracture, having grave financial, social and environmental consequences. In this paper, flexible joints are evaluated as an innovative mitigating measure against the consequences of faulting on pipelines. Joints are introduced in the pipeline in the fault vicinity, aiming at absorbing the developing deformation through relative rotation between adjacent pipeline parts, which then remain relatively unstressed. The effectiveness of flexible joints is numerically evaluated through advanced 3D nonlinear finite element modeling. Extensive parametric analysis is carried out to determine the effect of pipeline – fault crossing angle, fault offset magnitude, joint angular capacity, burial depth and diameter over thickness ratio on the joint efficiency. The uncertainty regarding the fault trace is also addressed. [ABSTRACT FROM AUTHOR]

In this paper, seismic behavior of gas supply networks is investigated by constructing a 24 m×24 m buried network and conducting an artificial earthquake test by detonating TNT explosives. The pipe network consists of typical welded steel pipes used in gas supply networks. Ground motion is produced by detonating 30 kg of TNT explosives buried 5 m below ground surface and 15 m away from the network. The test preparations are presented, including site selection, network layout, ground motion generation, and arrangements of different sensors. The measured ground acceleration, strain, and acceleration of welded steel pipes, and pipe–soil relative slippage are discussed. The deformation patterns of welded steel pipes are also analyzed and explained, including axial and bending deformations, systematic network characteristics, deformation relationship between ground and pipes, and dynamic response of buried pipes. [ABSTRACT FROM AUTHOR]

The goal of the present paper is to numerically investigate the effects produced by a vertical barrier located inside the ground, when the soil is subjected to seismic waves coming from a seismic source with a planar wave front. Firstly, the acceleration field on the ground surface is computed by varying both geometrical and mechanical properties of the barrier in order to determine, through a parametric study, the optimal barrier configuration to minimize the maximum magnitude of surface acceleration inside the shielded zone. Then, the above configuration is employed in the framework of a seismic analysis: a portion of a colonnade in Pompeii (Naples, Italy) is examined, with such a colonnade assumed to be located inside the shielded zone. A comparison of the seismic behaviour of such a heritage building is provided for the two cases of ground with or without the above vertical barrier. [ABSTRACT FROM AUTHOR]

This paper studies numerically the phenomenon of dip-slip faulting through homogeneous and zoned earth dams under steady state seepage conditions. Normal and reverse faults with various dip angles are included in this study. Two different materials, a clayey soil and a sand-clay mixture, for the homogeneous dam and core of the zoned dam are considered. The results show that the slope of the fault-induced rupture paths is independent of the fault orientation and its location at the base of the dam. The path of fault propagation near the dam surface could be mainly described by the conventional failure theories in the passive and active states. It is also possible to define general patterns for the propagation of rupture inside the body of the earth dams. These patterns are mainly characterized by the location, orientation and mechanism of the fault. The results indicate that reverse faults and mixed materials are responsible for comparatively higher pore water pressures. Emphasizing on engineering significance of the results, the general effects of rupture on the safety of the dams are also discussed. [ABSTRACT FROM AUTHOR]

This study discusses the effects of local site conditions on earthquake ground motion for city of Xanthi, North-Eastern Greece, focusing on the influence of complex site effects and soil non-linearity. Although city of Xanthi is characterized as a low seismicity area, documented strong earthquake events of past centuries indicate the necessity of an appropriate estimation of ground surface motion of the region. Therefore, a typical 2D cross-section along the city following an E-W direction is constructed, based on the synthesis of available geological, geotechnical and geophysical data of the broader area. 1D and 2D numerical models are generated utilizing the Finite Difference Method and site response is investigated for different seismic scenarios. Wave amplification is captured as a result of 1D resonance phenomena integrated with potential 2D complex wave effects, due to lateral propagation of the locally generated at the discontinuities surface waves. The additional, relatively to 1D, 2D amplification or de-amplification of ground shaking, in terms of its amplitude and its spectral content is quantified. The impact of soil deposits non-linearity on amplification level, as well as, on generated 2D wave fields is considered by implementing both equivalent-linear and non-linear approaches. The results reveal that, across the city, spatial variation of ground surface motion is obvious, attributed primarily to the variation of subsurface soil profiles. 2D wave effects have been generated signifying that, at particular site locations, ground motion is additionally amplified or de-amplified with respect to 1D response. However, 2D versus 1D differentiation has been calculated of ±20% in terms of PGA and spectral accelerations up to 1.0 s, in the majority of the examined sites, implying that site response even though, influenced by 2D resonance phenomena, could be sufficiently captured by an 1D approach. Moreover, it is shown that if soil non-linearity is properly accounted for, it may play an important role on the estimated ground response, since non-linear approach seems to produce lower amplification levels with regard to 1D and 2D equivalent-linear approaches. As a general trend across the investigated site, for the entity of the various scenarios, the numerically calculated response spectra exceed EC8 seismic code provisions. [ABSTRACT FROM AUTHOR]

Abrupt ground movements induced by earthquake, landslide, tunnelling and excavation, etc., pose significant threats to the safety of underground jointed pipelines. Most previous studies have investigated the response of buried pipelines through experimental tests and numerical simulations, but analytical solutions for the safety evaluation of jointed pipelines are limited. In this study, enhanced analytical solutions of pipe bending moment and joint shear force are derived, in which the effects of different pipe-fault crossing configurations and pipe-soil interactions are considered. Then, the allowable offset distances are investigated using the proposed solutions, respectively, for three different failure modes, i.e., joint shear failure, pipe bending failure, and joint pull-out failure. The results show that the joint pull-out failure governs the pipe safety when the burial depth is relatively shallow, while the pipe bending failure dominates when they are buried deeply. The worst pipe-fault crossing position is not at the pipe joint or the midspan of the pipe segment, but at one tenth of the pipe segment adjacent to the joint. The results offer new insights into buried DI pipe failure mechanism and provide a basis for the protection of buried DI pipes under abrupt transverse ground movement conditions. • Enhanced solutions are proposed for internal forces of ductile iron pipes under various fault-pipe crossing conditions. • Different failure modes for ductile iron pipes under under various strike-slip fault-pipe crossing scenarios are assessed. • Maximum allowable offset distances for ductile rion pipes under various strike-slip faulting conditions are evaluated. [ABSTRACT FROM AUTHOR]

Earthquake-induced shallow landslides are widely distributed in earthquake-affected areas. These hazards mainly originate from fragmented surface rock masses or surficial loose deposits overlaid on bedrock structure slopes. The seismic response of the surficial soil-bedrock slope is the key to revealing the dynamic failure mechanism of earthquake-induced landslides. This study investigates the seismic response of a surficial soil-bedrock step-like slope to evaluate the acceleration ground motion amplification along the slope. Parametric analysis focusing on the geometry of the surficial soil, thickness of the surficial soil, surficial soil-bedrock impedance contrast and geometry of the slope is conducted using the finite difference modeling code FLAC3D. The results show that both the surficial soil characteristics and geometry of the slope have great influences on the acceleration amplification factor in the horizontal direction (AAF). A maximum AAF zone is always formed near the interface between the surficial soil and bedrock, and the AAF always abruptly amplifies near the slope surface, especially at the crest of the slope. The potential dynamic failure surfaces under earthquakes are formed near the interface between the surficial soil and bedrock, which is in accordance with the AAF amplification zone of the slope, and the depth of the dynamic failure of the surficial bedrock slope is deeper than the static failure surface. It can be concluded that the topographic effect on the seismic response of the slope is strongly dependent on the surficial soil material characteristics and geometry. The findings of this study can contribute to a better understanding of the mechanism of shallow earthquake-induced landslides and have a number of important implications for disaster prevention and mitigation. • The interface between soil and bedrock causes acceleration to concentrate near it. • Different geometry of surficial soil shows different seismic amplification. • Slope geometry and interface jointly lead to complex seismic response of the slope. • Potential dynamic failure surface of the slope related to the PGA amplification zone. [ABSTRACT FROM AUTHOR]

In 2012 Northern Italy was hit by a seismic sequence with earthquakes of moderate local magnitudes and shallow hypocentral depths. After the main shocks of May 20, collapse of buildings and lifeline ruptures were widely observed in the epicentral area within a distance of about 15 km, where large acceleration values with prevailing vertical component were recorded. Locally, at a greater distance, intense and spectacular liquefaction effects were observed. They mainly affected the earthen embankments of the old Reno river channel (paleochannel), and, to a lesser extent, their immediate surroundings. In these far-field areas, ground surface accelerations were significantly low and not consistent with the spreading and extent of the observed liquefaction effects. A detailed geotechnical survey was performed to identify depth, location and behaviour of liquefied soil layers and to analyse their influence on ground response and surface liquefaction effects. Results from in situ and laboratory tests, performed under static and dynamic loading conditions, are presented herein and a complete geotechnical model of the ancient levees and the underlying soil deposit is proposed for numerical site-specific seismic analyses. More attention was paid to analysing the influence of non-linear behaviour of interbedded liquefied sands on the expected surface ground motion. Implications and limits of the results obtained are discussed with, finally, proposals for adjustments to 1-D linear equivalent models operating in the frequency domain, for taking into account stiffness degradation of liquefiable layers at high strain levels. [ABSTRACT FROM AUTHOR]

The uncertainties associated with the fault rupture model, i.e. down dip rupture width, subsurface rupture length and fault’s dip angle are not considered in the conventional probabilistic seismic hazard analyses (PSHA). The dip angle as an epistemic uncertainty is commonly assumed as a fixed value for a specific fault. Additionally, down dip rupture width and subsurface rupture length are determined from empirical relations. The main hypothesis of this paper was that the results of PSHA may be significantly influenced by considering the rupture model parameters as random variables instead of fixed values. The Monte Carlo simulation, as a powerful tool for uncertainty propagation analysis, was used for this objective. The NGA-West 2 database, as well as the Wells and Coppersmith (1994) [4] study was applied to describe the rupture model parameters in a stochastic manner. The results confirmed that hazard values derived from the Monte Carlo simulation method are significantly different from those derived from the classical approach. Depending on the attenuation relation and the style of faulting, theses differences leads to over/underestimation of hazard, especially at shorter periods in a characteristic band of region. [ABSTRACT FROM AUTHOR]

The present paper implemented a finite-element methodology to simulate the interaction behavior between tunnel and sandy soil deposit when a reverse fault rupture propagated from the base rock to the ground surface. The location of shear zones and propagation of subsurface rupture traces through overlying sand were discussed with the changes in the tunnel location, tunnel rigidity and soil relative density. The results indicated that the presence of a tunnel could have a significant influence on the fault rupture path. It was further shown that different factors affected the rotation and displacement of the tunnel. This study also investigated the evolution of a surface deformation profile using both centrifuge experiments and the finite element simulation. The results of finite element studies were verified using centrifuge experiments. Reasonable agreement between numerical and experimental results indicated the credibility of the numerical approach. Verified numerical methodology was then used to present a parametric study, offering further insight into the effect of different parameters on the soil-tunnel interaction phenomenon. [ABSTRACT FROM AUTHOR]

The dynamic response of a tunnel buried in a two-dimensional poroelastic soil layer subjected to a moving point load was investigated theoretically. The tunnel was simplified as an infinite long Euler–Bernoulli beam, which was placed parallel to the traction-free ground surface. The saturated layer was governed by Biot’s theory. Combined with the specified boundary conditions along the beam and saturated poroelastic layer, the coupled equations of the system were solved analytically in the frequency–wavenumber domain based on Fourier transform. The time domain responses were obtained by the fast inverse Fourier transform. The critical velocity of the considered structure was determined from the dispersion curves. The different dynamic characteristics of the elastic soil medium and the saturated poroelastic medium subjected to the underground moving load were investigated. It is concluded that, for coarse materials or fine materials subjected to the high-velocity loading, models ignoring the coupling effects between the pore fluid and the soil skeleton may cause errors. The shear modulus and the permeability coefficients of the saturated soil as well as the load moving velocity had significant influence on the displacement and pore pressure responses. [ABSTRACT FROM AUTHOR]

By using six 4.5 Hz geophones, surface wave tests were performed on four different sites by dropping freely a 65 kg mass from a height of 5 m. The receivers were kept far away from the source to eliminate the arrival of body waves. Three different sources to nearest receiver distances ( S ), namely, 46 m, 56 m and 66 m, were chosen. Dispersion curves were drawn for all the sites. The maximum wavelength ( λ max ), the maximum depth ( d max ) up to which exploration can be made and the frequency content of the signals depends on the site stiffness and the value of S . A stiffer site yields greater values of λ max and d max . For stiffer sites, an increase in S leads to an increase in λ max . The predominant time durations of the signals increase from stiffer to softer sites. An inverse analysis was also performed based on the stiffness matrix approach in conjunction with the maximum vertical flexibility coefficient of ground surface to establish the governing mode of excitation. For the Site 2, the results from the surface wave tests were found to compare reasonably well with that determined on the basis of cross boreholes seismic tests. [ABSTRACT FROM AUTHOR]

The discrepancies between the dynamic response obtained with "Beam on the nonlinear Winkler Foundation" method, as a 1D model, and the actual pile behaviour in the liquefiable ground have been identified and marked in the vast body of literature. In this study, a 1D formulation is presented for the soil-pile system which provided considerable insights on the physics of the soil behaviour around the pile in the liquefiable ground and its dependence on soil properties. Unlike the mechanical models that may or may not be generalizable, the presented method is controlled by the soil properties. By a concept that the pile response is mainly influenced by the response of soil located on a unit volume in the pile vicinity, a macro-element is hypothesized by introducing a volumetric constraint incorporating the soil volume changes. The nonlinearity of macro-element is coupled in between volumetric and distortional behaviours where an incremental plastic work is assumed. Hence a stiffness matrix operator is used, instead of a scalar value, to link the pile resistance components with displacement components. A hypo-elastic bounding surface model was developed in this framework to capture the complex mechanism of soil-pile interaction in the liquefiable ground and presents a very good accord with available field measurement and centrifuge study while the computational time reduces to a couple of minutes for an earthquake excitation. An application for the presented 1D modelling approach is presented by calculating the instantaneous period and damping of the soil-pile interaction system in the liquefiable ground. • A 1D formulation is presented for the soil-pile system in liquefiable ground. • a macro-element is hypothesized by introducing a volumetric constraint incorporating the soil volume changes. • The nonlinearity of macro-element is coupled in between volumetric and distortional behaviours. • A stiffness matrix is used in linking pile resistance to the displacement components. • Instantaneous first-mode period and damping of the soil-pile system were calculated. [ABSTRACT FROM AUTHOR]

The 2008 Wenchuan earthquake with M w 7.9 occurred at Yingxiu County in Longmenshan thrust fault belt, southwest China, having triggered a huge amount of slope failures. This paper applied a detailed inventory with more than 190,000 slope failures and strong ground motion records of 187 seismic stations to analyze the qualitative and quantitative relations between slope failure distribution and seismic parameters. The results revealed that slope failure distribution was exponentially decreased with the increment of epicentral distance and distance from surface fault rupture; peak ground acceleration (PGA) on the hanging wall side was apparently larger than that on footwall side. Linear correlation between concentration of slope failures (LNC) and the percentage of the area affected by slope failure (LAP) and PGA was demonstrated by statistical analysis, which revealed that 0.18~0.21 g horizontal PGA was the threshold value of the occurrence of slope failure. Furthermore, this paper presented an empirical model for the attenuation relation of slope failure distribution. [ABSTRACT FROM AUTHOR]

Surface fault rupture has caused significant damage to structures in several earthquakes. The propagation of the bedrock fault rupture through the overlying soil deposit has been studied by several researchers; however, the effects of fault rupture dynamics, as opposed to pseudostatic fault movement, have not yet been evaluated. There is the potential for dynamic effects to influence significantly structural damage due to the rapid rate of deformation imposed by surface fault rupture. Numerical simulations are performed to analyze the effects of the rate of fault rupture on dip-slip surface fault rupture for free-field and soil-structure interaction conditions. The numerical results indicate that in some limited scenarios, fault rupture dynamics can influence the amount of structural damage expected for a structure located near a fault. However, in most scenarios, fault rupture dynamics is expected to play a secondary role compared to fault, soil, and structural characteristics in evaluating building performance. [ABSTRACT FROM AUTHOR]

It is shown that the observed loss of coherency of synthetic strong motion on ground surface for separation distances less than about 100 m can be described in terms of the dispersion of strong motion waves. Additional contributions to the loss of coherency from variations of material properties in the soil and from geometrical departures from perfectly flat ground surface and irregular layer geometries are not considered in this paper. It is also shown that the synthetic surface displacements over a large rectangular area (100×100 m) on ground surface can be described well by a flat surface undergoing translations and rotations only, and with only minor departures from the plane flat surface. [ABSTRACT FROM AUTHOR]

Incremental Dynamic Analysis (IDA) involves a series of nonlinear response history analyses with a suite of incrementally scaled ground motion records. Although IDA is perhaps the most comprehensive seismic performance assessment method, it receives criticism because several ground motion records are scaled up until the structure collapses. The scaling practice often results to unrealistic multipliers, thus modifying the amplitude of the ground motion and introducing bias on the structural performance estimation. Record scaling is a common practice in earthquake engineering due to the lack of natural records corresponding to large magnitudes and/or small distances from the fault rupture location. In this work we use a large number of ground motion records to compare the predictions of IDA with that of unscaled ground motions and we propose a new methodology in order to quantify the bias introduced in IDA. Apart from natural records, we have conducted broadband ground motion simulations for rupture scenarios of weak, medium and large magnitude events in order to expand our record database. The investigation is performed on a series of inelastic single-degree-of-freedom systems and on two multistory steel moment frame buildings. The results pinpoint both qualitatively and quantitatively, for the full range of limit-states, the bias that IDA introduces on the structural performance estimation. [ABSTRACT FROM AUTHOR]

To explore the optimal seismic performance of new EPS pile, we carried out a series of shaking table test by comparing different pile types. We measured and obtained the seismic data with various attributes, such as the characteristic image of different probability horizontal seismic action, acceleration and dynamic soil pressure. By analyzing the time-domain characteristics of multi-attribute data such as deformation characteristics and acceleration, we revealed the instability mode of the slope model and the regional response characteristics of particle spatial position. Based on the Fast Fourier Transform (FFT) and Statistical Probability Sperm Matrix (SPSM), we proposed the damage level correlation between the spectral characteristics of acceleration and dynamic soil pressure. We obtained the relationship between the variation of the frequency and specific period between acceleration and dynamic soil pressure at different seismic stages through in-depth study, and then calculated the regional differences of spectrum displacement (S d) by using Seism Signal. In the frequency domain of acceleration and dynamic soil pressure signals, the predominant frequencies were mostly concentrated in 0.5–8 Hz. Under high seismic acceleration, the amplitude frequency of acceleration spectrum of conventional pile and EPS pile was both 1.51 Hz, and the dominant frequency of dynamic soil pressure was significantly different. There was a positive correlation between seismic acceleration and dynamic soil pressure. The shift of frequency profile and main frequency band of EPS pile was mainly caused by the propagation stage after the acceleration main shock. Under high seismic acceleration, the deformation of EPS pile and conventional pile occurred to some extent. EPS plate was used as the damping layer to buffer and dissipated the deformation of the slope under earthquake, and its effect was linked to the seismic data attributes. The spectral displacement of EPS pile was reduced as a whole was higher than that of conventional pile. The slip surface of pile body was sensitive to earthquake, and it was easy to become the weak seismic link of the EPS pile. These results are helpful for us to provide a theoretical basis for improving the reliability optimization design of dynamic parameters of the pile structure. • For the first time, we carried out the shaking table test of new type EPS pile for soil slope reinforcement. • We revealed the regional response characteristics of EPS pile particle spatial position. • We obtained the damage level correlation between acceleration and dynamic soil pressure spectral characteristics. • We proposed the relationship of frequency between acceleration and dynamic soil pressure at different vibration stages. • We obtained the regional difference of the deformation and S d of the EPS pile during the seismic action. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the fault rupture zone traversing a seismically isolated bridge is investigated utilizing a finite element model of a section of the Bolu Viaduct and a set of synthetic broadband strong ground motions simulated for the Bolu Viaduct site due to the 1999 Duzce earthquake. Both the original and a potential retrofit seismic isolation system designs are considered in the analyses. The results show double isolation system demands when fault crossing is considered, as compared to the case where fault crossing is ignored. The pier drift demands, however, remain comparable in both cases. Furthermore, the location of fault crossing along the bridge length, as well as the fault orientation with respect to the bridge longitudinal direction are shown to influence substantially the response of the seismically isolated bridge. Isolation system permanent displacements are greatly influenced by the restoring force capability of the isolation system when fault crossing effects in the excitations are ignored. In the case of fault crossing, the permanent displacements of the isolation system are dominated by the substantial permanent tectonic displacement along the fault trace which is imposed upon the structure. The results of this study contribute to developing a better understanding of how seismically isolated bridges respond when traversed by fault rupture zones. The lack of analyses and design guidelines for bridges crossing faults in international standards renders this study a useful reference for the profession. [Copyright &y& Elsevier]

Abstract: The present work deals with 1D and 2D ground response analysis and liquefaction analysis of alluvial soil deposits from Kanpur region along Indo-Gangetic plains. Standard penetration tests and seismic down hole tests have been conducted at four locations namely IITK, Nankari village, Mandhana and Bithoor at 1.5m interval up to a depth of 30m below the ground surface to find the variation of penetration blows and the shear wave velocity along the depth. From the selected sites undisturbed as well as representative soil samples have been collected for detailed soil classification. The soil profiles from four sites have been considered for 1D and 2D ground response analysis by applying the free field motions of three Himalayan earthquakes namely Chamba earthquake (M w—5.1), Chamoli earthquake (M w—6.4) and Uttarkashi earthquake (M w—6.5). An average value of Peak Ground Acceleration (PGA) obtained from 1D and 2D analysis is considered for liquefaction analysis and post-liquefaction settlement. The excess pore water pressure ratio is greater than 0.8 at a depth of 24m from ground surface for IITK, Nankari village, Bithoor sites. More than 50% of post liquefaction settlement is contributed by layers from 21–30m for all sites. In general, the soil deposits in Kanpur region have silty sand and sand deposits and are prone to liquefaction hazards due to drastic decrease of cyclic resistance ratio (CRR) at four chosen sites in Kanpur. [Copyright &y& Elsevier]

Fault rupture is a complex phenomenon and substantial secondary ruptures have been observed. Such ruptures may cause damage to pipelines laying in the vicinity of main faults without intersecting them. The current study investigates numerically the response of buried steel pipelines crossing secondary faults, following a decoupled approach. Initially, a 3D numerical model is used to calculate soil displacements, which subsequently are applied to another numerical model for the calculation of pipe distress. Sandy soil response is realistically simulated by adopting an elastoplastic Mohr-Coulomb constitutive model with isotropic strain softening. Both models are compared with experimental results for singe fault rupture. The impact of several parameters is examined, such as fault type, soil layer properties and thickness, and different pipe routes with respect to the faults. Useful conclusions are drawn regarding the applicability of the proposed numerical approach as well as the severity of pipe distress under secondary faulting. [Display omitted] • Pipelines are usually designed to avoid intersections with active seismic faults. • Rupture of an active fault may lead to the rupture of secondary faults. • Secondary faults may have severe impact on pipelines in the vicinity of main faults. • The numerical parametric study shows that this impact can be detrimental. • Soil and seismotectonic conditions play a crucial role on the pipeline distress. [ABSTRACT FROM AUTHOR]

The 2020 M7.0 Samos earthquake had occurred on the north of Samos Island; however, structural damage was observed in İzmir-Bayraklı, which is located approximately 65 km away from the epicenter. Strong ground motions recorded in İzmir Bay showed unique site amplifications, mostly due to the interaction between the basin and deep alluvial deposit response. The objective of this study is to evaluate the predictive performance of current ground motion models (GMMs) for estimating the recorded strong motions, especially the recordings over or near the Bayraklı-Bornova basin. 66 strong motion stations from Turkey with rupture distance (R RUP) < 200 km are used in the residual analysis, considering the ambiguities in the magnitude and depth to the top of the rupture estimations. Event terms of the earthquake for tested GMMs are found to be small and lie within the expected scatter, except for T = 0.5–1.5 s spectral accelerations. Event-specific distance attenuation for R RUP <100 km is consistent with the median predictions of current GMMs; however, the distance scaling for 100 km

The influence of soil inhomogeneity on earthquake surface fault rupture is analyzed using the discrete element method (DEM). Particle assemblages are produced with layers having contrasting relative density. Similar to that observed in homogenous soil simulations, loose layers tend to absorb the localized shear deformation from underlying dense layers and disperse it over a broader area. However, the rupture can re-localize as it moves into an overlying dense layer. The ground surface deformations produced by fault rupture through layered soils are bounded by the ground surface deformation produced in homogeneous soil. The presence of a thin layer does not significantly alter the path of fault rupture propagation of a steeply dipping dip-slip fault. Conversely, a loose thin layer within dense soil can divert the path of fault rupture propagation during shallow reverse fault rupture by providing a kinematically compatible path of low shear resistance. Stresses are homogenized within the simulations to highlight the capability of DEM to capture the response of granular materials in scenarios that are difficult to achieve physically in the laboratory. • Soil layers are produced with different relative densities using DEM in 3D. • The dependence of fault rupture path on relative density is captured in each layer. • Ruptures absorbed in loose layers can re-localize in overlying dense layers. • Fault rupture is affected strongly by layer thickness and number of layers. • Deformations in homogeneous soils bound those produced in layered soils. [ABSTRACT FROM AUTHOR]

To mitigate the seismic damage of the fault-crossing tunnel, this paper researches the scope influenced by the fault and proposes a setting method of the segmental lining. It is concluded that the segmental lining has a significant effect on reducing the shear stresses and compressive stresses, and the shorter the segment, the more obvious the effect. Furthermore, the normalized parametric analyses show that the seismic damage degree of fault-crossing tunnel increases with the decrease of the value of D / t (D is the tunnel diameter and t is the wall thickness), and the arch springing with the smallest D / t is the most critical position to be damaged. The middle section of fault rupture zone is the most dangerous and the seismic effect of the tunnel structure on the hanging wall is more severe than the seismic effect on the footwall. The proposed influenced scope of tunnel structure and the setting method of the lining segment can provide a reference for the aseismic design of the fault-crossing tunnel. • The influenced scopes of fault-crossing tunnel with varying fault widths were determined. • The design concept of the segmental lining that used to counter the fault was proposed. • The seismic response of tunnel lining was researched based on non-dimensional groups. [ABSTRACT FROM AUTHOR]

Directivity is a phenomenon perceived during fault ruptures wherein the ground motion and spectral response in the direction of the rupture is more significant than in any other direction. The objective of this study is to evaluate the variability in characteristics of near-fault ground motions as well as the ductility demand on structures due to directivity based on simulations of strike-slip earthquake events by employing SPECFEM3D, a physics-based ground motion simulation code. To understand the finite fault propagation effect, a source effect, the vertical strike-slip fault is considered to be embedded in an elastic half-space, to prevent the influence of path and site effects. Two scenarios are designed based on the positioning of nucleation asperity (NA): (1) in the middle of the fault face to simulate bilateral (BL) rupture and (2) shifted to one end for the case of unilateral (UL) rupture. The ground motions at near-fault stations, located in a racetrack configuration around the surface trace of the fault, are analyzed. In addition to a high spectral content in the forward directivity stations as a result of UL rupture, directivity velocity pulses identified in the fault-normal components are higher than the fling step velocity pulses in the fault-parallel component for the racetrack stations considered. Furthermore, the study examines the correlation between ductility demands computed based on elastoplastic rheology with direct point parameter and ground motion intensity measures for directivity and fling step stations. • Rupture dynamics based simulations were performed for directivity and non-directivity ground motions. • A unilateral scenario (hypocenter to one side of the fault) and a bilateral rupture (hypocenter at the middle along strike. • Influence of Nucleation Asperity (NA) on pulse period is shown for five locations arranged around the fault on a racetrack. • The effect of NA on ductility demand of structures displaying low, moderate, and high natural periods was highlighted. • Correlation of inelastic response with directivity correction factors in literature, and intensity measures discussed. [ABSTRACT FROM AUTHOR]

Abstract: An extensive investigation has been made into the interaction between topographic amplification and soil layer amplification of seismic ground motion. This interaction is suggested in the literature as a possible cause for the differences between topographic amplification magnitudes observed in field studies and those obtained from numerical analysis. To investigate this issue a numerical finite element (FE) parametric study was performed for a slope in a homogeneous linear elastic soil layer over rigid bedrock subjected to vertically propagating in-plane shear waves (Sv waves). Analyses were carried out using two types of artificial time history as input excitation, one mimicking the build-up and decay of shaking in the time histories of real earthquake events, and the other to investigate the steady-state response. The study identified topographic effects as seen in previous numerical studies such as modification of the free-field horizontal motion, generation of parasitic vertical motion, zones of alternating amplification and de-amplification on the ground surface, and dependence of topographic amplification on the frequency of the input motion. For the considered cases, topographic amplification and soil layer amplification effects were found to interact, suggesting that in order to accurately predict topographic effects, the two effects should not be always handled separately. [Copyright &y& Elsevier]

Abstract: In this work a parametric study of the (overturning) rocking instability of a free-standing rectangular rigid block under a ground harmonic pulse is thoroughly discussed assuming that the friction between the rigid block and ground surface is sufficiently large to exclude sliding. Attention is focused on the minimum amplitude ground acceleration which yields (overturning) rocking instability. The individual and coupling effects on overturning instability of the stockiness parameter of the block (width to height ratio) in connection with the height of the rigid block and its initial conditions (imperfections) are examined in detail. Two modes of rocking instability with or without impact under a one-sine and a one-cosine pulse with different ground excitation periods are discussed. With the aid of phase-plane portraits rocking instability criteria which lead to closed form solutions for establishing the minimum amplitude ground acceleration, are properly assessed. [Copyright &y& Elsevier]

Abstract: In this study, we use a stochastic finite-fault technique based on a dynamic corner frequency to investigate how the fault and slip models affect the high frequency simulations of the 1999 Izmit (Turkey) earthquake. Seven different rupture models, one of them generated using common fault parameters and random slip distribution are tried to obtain the best matching with the observations. The synthetic seismograms computed in the frequency band 0.1–25Hz are compared with the observations both in time and frequency domain. Six accelerometric stations located close to the observed surface rupture are chosen for the comparisons considering the fact that the slip contributions are visible at these station records better than the other stations. We also estimated average H/V spectral ratios using the available accelerometric recordings to take into account site amplification at each site. We also acquired ambient noise data at some stations that lack sufficient earthquake records. The results show that none of the rupture models fully simulate the observations at all the stations. Most of the rupture models underestimate the Fourier amplitudes at frequencies lower than 0.4Hz, whereas overestimate them at higher frequencies. The underestimation may result from a directivity effect which likely causes higher amplitudes on the observed ground motions in low frequency band. While all the rupture models display similar average bias functions, the minimum average error for spectral amplitudes is obtained for the rupture model of Bouchon et al. (2002). The achievement of the random slip distribution model also yields satisfactory results. After we have optimized the rupture model, we have simulated the strong ground motions on a regular grid (0.2°×0.2°) covering the study area for bedrock conditions. In total, we have estimated peak accelerations and peak velocities at 135 points. The results show that the maximum acceleration values during the Izmit earthquake reached 785cm/s2, and the largest velocity values were around 75cm/s. The peak ground accelerations are still smaller than those predicted by the empirical relations but are well above the observed ones. The low accelerations might be attributed to the low stress drop that might be due to the large rupture length. [Copyright &y& Elsevier]