Seismic Deformation Research Articles

Investigation of the Effective Numerical Model for Seismic Response Analysis of Concrete-Faced Rockfill Dam on Deep Overburden

The construction of high rockfill dams on deep overburden in seismically active regions poses significant challenges. Currently, there are no standardized guidelines for defining the computational domain range in seismic analysis, necessitating the establishment of a universally applicable computational domain range that optimizes the balance between computational accuracy and efficiency. This has critical engineering implications for the seismic analysis of rockfill dams on deep overburden. This study employed the seismic wave input method to consider the dynamic interaction between the dam, overburden, and infinite domain. A systematic investigation was conducted on a concrete-faced rockfill dam (CFRD) constructed on deep overburden, considering the influences of overburden thickness, dam height, overburden properties, soil layer configuration, ground motion intensity, and the frequency content of the seismic waves. The acceleration response and seismic deformation of the dam were analyzed. Subsequently, the computational domain range corresponding to various levels of acceptable engineering precision was established. The results indicated that the lateral boundary length should extend a minimum distance equal to the sum of 3 times the overburden depth and 1.2 times the maximum dam height. Additionally, the depth below the overburden–bedrock interface should extend at least 1.2 times the maximum dam height. This study provides a crucial foundation for determining the optimal computational domain range in the seismic analysis of rockfill dams constructed on deep overburden.

Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests

Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.

Spatiotemporal evolution of post-seismic deformation caused by large earthquakes around the Pacific and its impact on plate movement

SUMMARY The fully relaxed deformation caused by an earthquake refers to the total deformation of the earth caused by the earthquake, including the coseismic deformation and the total effect of post-seismic stress relaxation in the mantle on crustal deformation. An in-depth investigation into post-seismic and fully relaxed deformation resulting from large earthquakes is conducive to comprehending the feedback effect of earthquakes on plate motion. In this paper, we first calculated theoretically the coseimic, post-seicmic and fully relaxed deformations caused by the Tohoku-Oki Mw9.0 earthquake using the spherical dislocation theory. The post-seismic displacement caused by the great earthquake leads to the continuous convergence of plates on both sides of the seismogenic fault, which will certainly facilitate the downward insertion of the subduction plate. As time goes by the influence range of seismic deformations becomes larger and larger. The Tohoku-Oki Mw9.0 earthquake can produce >5 cm of cumulative post-seismic horizontal displacement at a far place like the East Pacific Rise over 100 millenniums. Then, we built slip models of 375 earthquakes with Mw7.0 and above in the circum-Pacific seismic belt, calculated the cumulative post-seismic deformations of them, and found that significant post-seismic horizontal displacements covered the entire Pacific Ocean. The post-seismic deformation field caused by the 2011 Tohoku-Oki Mw9.0 earthquake, the 2010 Chile Mw8.8 earthquake, the 1964 Prince William Sound Mw9.1 earthquake and the 1960 Chile Mw(9.3–9.4) earthquake determines the overall distribution pattern of the deformation field in the Pacific region. Those large earthquakes around the Pacific make the total Pacific Plate present a tension strain in the northwest–southeast direction. The one at the East Pacific Rise reaches 300–400 nstr, with orientation of principle strain approximately perpendicular to the Rise. This tensile strain is bound to encourage transverse expansion of the mid-ocean ridge. By a logical extension, the post-seismic stress relaxation in the mantle caused by past earthquakes should be an important driving force for the current plate movement, in addition to the classic driving force like negative buoyancy and plate material phase transition. This study proves theoretically that there is a two-way relationship between great earthquakes and plate movement, and the viscous structure of mantle plays a key role in the relationship.

Effect of geometry on the natural frequency and seismic response characteristics of slopes subjected to pulse-like ground motions

Near-fault regions are particularly vulnerable to seismic-induced landslides due to the intense energy pulses in near-fault ground motions (NFGMs). These pulses, shaped by terrain geometry and material properties, significantly influence seismic response and slope stability. This study investigates the impact of slope geometry on natural frequency and seismic response characteristics under both pulse-like ground motions (PLGMs) and non-pulse ground motions (non-PGMs). The results show that increasing slope height lowers natural frequency, making the slope more susceptible to resonance with seismic waves, thus amplifying ground motion and increasing instability. Similarly, steeper slopes also reduces the natural frequency, heightening instability by up to 0.17%. PLGMs generate seismic responses approximately 7% stronger than those induced by non-PLGMs. Furthermore, as the frequency of PLGMs rises, so does their destructive potential. Material analysis reveals that Rock Class A has a natural frequency 68% higher than Rock Class D, making it significantly resistant to seismic deformation. These insights are essential for designing more resilient slopes in seismic-prone regions.

Seismic Deformation Analysis of Precast Concrete Pipe Hybrid Based on 3D LiDAR and Unmanned Aerial Vehicle Photogrammetry

Seismic Deformation Analysis of Precast Concrete Pipe Hybrid Based on 3D LiDAR and Unmanned Aerial Vehicle Photogrammetry

Correlating the seismic acceleration of reinforced concrete moment-resisting-frames with structural and earthquake characteristics

Nonstructural components (NSCs) are elements within the building unrelated to the lateral load-carrying system. Failure of NSCs during earthquakes can result in casualties, significant economic losses, disabled critical infrastructures, and loss of building functionality. The NSCs can be categorized into two primary groups: deformation-sensitive and acceleration-sensitive. Thanks to well-established seismic design guidelines and standards, buildings may suffer minor seismic deformations – resulting in lesser damage to deformation-sensitive components. However, planning under the peak floor response or peak floor acceleration (PFA) is getting much less attention – exposing the acceleration-sensitive components to greater risk. This manuscript develops equations for moment-resisting reinforced concrete frames (MRRCFs) that estimate the total floor acceleration. The data is gathered based on 984 inelastic response simulations, elaborated to create an idealized equation based on the earthquake characteristics. The developed equation offers engineers a quantitative approach to understanding the inertial forces applied to the NSCs within the building during earthquakes, allowing them to plan for potential risks due to earthquakes.

Geological and hydrogeological drivers of seismic deformation in L’Aquila, Italy: insights from InSAR analysis

Historical and recent earthquakes have struck the city of L'Aquila, located in the axial zone of the Central Apennines, Italy, causing severe damage to the historic centre. Recent studies have shown that higher intensity of damage to buildings in L’Aquila downtown, both in the case of the 2009 earthquake (Mw: 6.29) and the 1703 earthquake (Mw: 6.7), is associated with higher post-seismic subsidence rates, detected through A-DInSAR maps, in the time range 2010–2021. This finding suggests the existence of geological factors that drive deformation (and building damage). The availability of long time series of InSAR data acquired from the Cosmo-SkyMed and Sentinel-1 missions, has enabled us to analyze the relationships between ground deformations and geological, hydrogeological, and geomorphological factors that may affect them. The correlation analysis between predisposing factors and SAR deformation has highlighted an increase in subsidence strongly conditioned by the outcropping lithology, showing how compositional variations within lithology can significantly influence ground deformations. Furthermore, hydrogeology has been recognized as playing an important role in determining deformation processes: the water table depth locally influences long-term subsidence, while seasonal fluctuations in the water table may be responsible for secondary areal variations in ground deformations.

Deformation of solid earth by surface pressure: equivalence between Ben-Menahem and Singh’s formula and Sorrells’ formula

SUMMARY Atmospheric pressure changes on Earth’s surface can deform the solid Earth. Sorrells derived analytical formulae for displacement in a homogeneous, elastic half-space, generated by a moving surface pressure source with speed $c$. Ben-Menahem and Singh derived formulae when an atmospheric P wave impinges on Earth’s surface. For a P wave with an incident angle close to the grazing angle, which essentially meant a slow apparent velocity $c_a$ in comparison to P- ($\alpha ^{\prime }$) and S-wave velocities ($\beta ^{\prime }$) in the Earth ($c_a \ll \beta ^{\prime } \lt \alpha ^{\prime }$), they showed that their formulae for solid-Earth deformations become identical with Sorrells’ formulae if $c_a$ is replaced by $c$. But this agreement was only for the asymptotic cases ($c_a \ll \beta ^{\prime }$). The first point of this paper is that the agreement of the two solutions extends to non-asymptotic cases, or when $c_a /\beta ^{\prime }$ is not small. The second point is that the angle of incidence in Ben-Menahem and Singh’s problem does not have to be the grazing angle. As long as the incident angle exceeds the critical angle of refraction from the P wave in the atmosphere to the S wave in the solid Earth, the formulae for Ben-Menahem and Singh’s solution become identical to Sorrell’s formulae. The third point is that this solution has two different domains depending on the speed $c$ (or $c_a$) on the surface. When $c/\beta ^{\prime }$ is small, deformations consist of the evanescent waves. When $c$ approaches Rayleigh-wave phase velocity, the driven oscillation in the solid Earth turns into a free oscillation due to resonance and dominates the wavefield. The non-asymptotic analytical solutions may be useful for the initial modelling of seismic deformations by fast-moving sources, such as those generated by shock waves from meteoroids and volcanic eruptions because the condition $c / \beta ^{\prime } \ll 1$ may be violated for such fast-moving sources.

A ductile seismic design strategy for the cross-aisle direction of racking systems

Due to their lightness and simple connectivity, steel racking systems are typically considered as “low-dissipative” structures, which is reflected in the modern seismic codes by the absence of capacity design and the adoption of low behaviour factors. This limited capability of stress redistribution significantly increases the vulnerability of racks under beyond-design seismic hazards and raises the demand for more resilient designs. Along these lines, the proposed Plastic Ovalization Strategy (POS) attempts to increase the ductility of the individual upright frames comprising the cross-aisle direction of racks, and at the same time to preserve their low-cost and easy-to-assemble nature. This is achieved by tasking the bearing failure mechanism of the diagonal bolt hole to absorb seismic deformations, while capacity design is employed to keep the rest of the structure in the elastic zone. Following a detailed discussion on the motives and basic principles of the strategy, two high-rise racking systems are designed twice by professional engineers, once using standard approaches and then by additionally employing the proposed POS rules. Finally, the two design solutions are compared by conducting a comprehensive seismic assessment, which employs a phenomenological macro-model comprising elastic elements and nonlinear springs to simulate the bearing failure mechanism.

The strain demand of reinforced concrete bridge columns under seismic loading

The steel in reinforced concrete (RC) members that form plastic hinges must possess sufficient strain capacity to dissipate seismic deformation demands. Unfortunately, there is limited information on the seismic strain demands of bridge column plastic hinges. Instead, designers rely on a perception of cyclic strain capacity that is an approximate rule of thumb. A standard methodology needs to be established for quantifying the strain demand on these structural members as a function of the expected seismic hazard. To develop this methodology, 1944 columns were analyzed with nonlinear time-history analyses (NLTHAs) using ground motions from a range of earthquakes. This study evaluates the strain demand on RC bridge columns by defining the relationship between the strain demand and earthquake intensity. The results of the model are defined in terms of the peak tensile strain of the reinforcing bar, [Formula: see text]. The earthquake intensity with the highest correlation to the [Formula: see text] was determined to be the elastic spectral displacement at the optimal period ([Formula: see text]), which is defined as 75% of the effective period. The relationship between [Formula: see text] and [Formula: see text] can be used to predict the strain demand for an RC bridge column at a given geographic location. Results are presented as a probability density function (PDF), representing strain demand, compared to a PDF of the column capacity. The intersection of the capacity curve and demand curve represents the maximum acceptable strain given as a function of [Formula: see text]. This methodology can help understand the demand placed on a structural system given a region’s seismicity.

Seismic Deformation Analysis of the 28th September 2018 Palu Earthquake (7.5 Mw) Using InaCORS Station Data and Okada Model

This study employs the Okada Method to analyze the horizontal seismic deformation of the Palu earthquake on September 28, 2018, with a magnitude of 7.5 Mw. Data from InaCORS stations (WATP, CPRE, CPAL, TOBP, and CMLI) strategically positioned near the earthquake epicenter were processed using Gfortran software, and deformation was mapped using GMT software. The analysis focuses on the 100 Days of Year (DOY) period from August 6 to November 28, 2018. Results indicate that during the co-seismic phase (DOY 272), InaCORS stations experienced deformations ranging from 477.130 mm to 7.7852 mm. The magnitude of deformation varied based on station proximity to the epicenter, with the largest displacement observed at TOBP and the smallest at CPRE. Station movements were divergent, with northern stations shifting northward and southern stations moving southward. Subsurface slip reached 1449.23 mm, affecting an area measuring 145 km by 76 km at a depth of 8 km, dip of 65˚, strike of 351˚, and rake of -46˚. These findings contribute valuable insights into the seismic impact on the Earth's crust, aiding seismic hazard assessments in the region

DEFORMATION INTERACTION OF STRONG EARTHQUAKES OF 2010–2016 IN THE ZONE OF INFLUENCE OF THE HIKURANGA SUPERPLUME (NEW ZEALAND) ACCORDING TO GPS OBSERVATIONS

Between 2010 and 2016, a series of 11 strong M>6 earthquakes occurred in New Zealand. In the area covering the epicentral zones of these seismic events, the spatiotemporal characteristics of movements and deformations of the Earth’s crust were obtained based on the processing of continuous satellite GPS observations at 64 points of the geodetic network. Using these data, we have studied the evolution of horizontal movements and deformations in order to reveal the possible relationship between the observed deformational and seismic processes. Analysis has been made on the total shear deformation, since the main tectonic structures of the region are faults with a shear mechanism of displacement of their sides. The presence of a giant mantle superplume in the area was the reason for the study of the behavior of horizontal dilatation deformation, and horizontal and vertical crustal motions. Based on the obtained digital deformation models, there were created kinematic visualizations, which are synoptic animations providing direct observations of the seismic deformation process and their heuristic analysis. The study revealed that a series of the strongest earthquakes may be interconnected by a long-term single deformation process, which is caused by the occurrence of an anomalous total shear deformation. The general maximum of shear deformation, dilatation deformation, and horizontal and vertical displacements are concentrated in the center of mantle superplume activity. Prior to strong seismic events, there occur zones of deficit (minimum) displacements of the Earth’s crust in the area of future epicenters, which is of research interest in terms of predicting their locations.

The crypt complex «city of the dead» in the Dargavs village (North Ossetia) is a witness to the late medieval earthquake in the Caucasus

During the study of the crypt complex near the Dargavs village in North Ossetia, seismic deformations were detected in some burial structures. The presence of only a few damaged crypts among the many relatively wellpreserved burial structures indicates that a significant earthquake took place at the very beginning of the functioning of the burial ground. Its local seismic intensity was VII-VIII points. The age of the earthquake is the XVI century. The data obtained will help to supplement the catalog of strong earthquakes in the Caucasus and clarify the assessment of its seismic hazard based on longterm seismic data.

Seismic fragility analysis of isolated bridges considering landslide-induced differential settlements

The structural safety of bridges and viaducts can be affected by the combination of different hazardous sources. This paper presents a study on the seismic fragility of continuous-deck bridges isolated through elastomeric bearings subjected to ground settlements induced by slow-moving landslides. In the investigated bridge typology, the relative differential displacement of bridge substructure components can involve significant strains of the bearing devices reducing their seismic deformation capacity and determining the increase of bridge fragility. Based on observations on a real case-study bridge, a parametric analysis is carried out to investigate the sensitivity of bridge fragility considering several realistic landslide-induced differential settlement scenarios and variable characteristics of the elastomeric bearings. Seismic fragility curves considering specific settlement scenarios are computed and compared to the undeformed condition to estimate the influence on fragility curves. Results show that a significant increase in fragility is registered for settlement scenarios inducing localized settlements of substructure components and for high-damping nonlinear seismic response.

Seismic Deformation Response Analysis of Shallow Buried Section at the Entrance and Exit of River Crossing Tunnel

Ensuring the safety of tunnel structures in unique underwater environments is of paramount importance. This study focuses on the entrance section of a river-crossing tunnel, characterized by shallow burial depths with significant variations. The tunnel structure faces challenges related to structural weakening, and its deformation response exhibits specific characteristics under seismic loads. Numerical simulation software was employed to model and calculate the deformation response of the shallowly buried entrance section under seismic load conditions, assessing the impact of changes in tunnel structural strength and burial depth. The results reveal the following key findings: (1) As the tunnel structure weakens, structures of varying strengths primarily experience vertical deformation under seismic loads, followed by horizontal deformation. Furthermore, as the tunnel structure’s strength decreases, it exhibits an increasing trend in deformation. Routine maintenance should prioritize locations where the tunnel structure weakens, implementing timely reinforcement measures to ensure adequate load-bearing capacity. (2) Considering the influence of tunnel structural burial depth, lateral deformation values rank in descending order from largest to smallest, including the tunnel bottom, middle carriageway, middle of the tunnel, and tunnel vault, while the overall lateral deformation of the tunnel is not significant, it decreases as the structural burial depth increases. (3) In relation to tunnel structural burial depth, vertical deformation values generally exceed horizontal deformation values. Sections with the highest to lowest deformation values are the tunnel bottom, middle lane of the tunnel, middle of the tunnel, and position of the tunnel vault. With increasing burial depth, the vertical deformation values decrease at a slower rate than horizontal deformation. The tunnel structure demonstrates a higher sensitivity of lateral deformation to changes in burial depth factors.

Deformation behavior of rectangular underground structures in liquefiable deposits correlated to ground motion intensity measures

Rectangular underground structures in liquefiable deposits are susceptible to larger deformation during earthquake events. The intensity of earthquake motions, as one of the critical factors that would induce large deformation of underground structures in liquefiable deposits, however, was not received enough recognitions. In this paper, nonlinear dynamic analyses with a probabilistic seismic demand model (PSDM) were conducted for a two-dimensional liquefied soil-structure system, considering a variable thickness of liquefiable layer below the structure. The nonlinear soil behavior was simulated by the nonlinear constitutive model PDMY02. The constitutive parameters of saturated sand were calibrated by a slope model in the centrifuge test from LEAP-2017. Interstory drift ratio (IDR) and uplift ratio (UR) of underground structures were selected as engineering demand parameters (EDP). There were totally 18 recorded earthquake motions and 8 intensity measures (IMs) included for the PSDM. Numerical results show that the uplift behavior of underground structures is more sensitive to the variable thickness of liquefiable deposits compared to the horizontal drift of the structure. According to the performance of correlation, efficiency, practicality and proficiency, the velocity-related IMs are more appropriate than the acceleration-related IMs for the evaluation of seismic deformation behavior of underground structures. The deformation response as well as the adaptability of velocity-related IMs are further discussed and evaluated by considering more general cases including different buried depths and height-width ratios for rectangular underground structures.

Co- and Pre-Seismic Crustal Deformations Related to Large Earthquakes Between Years of 2009 and 2023 Using Continuous CORS-TR GNSS Observations in the Anatolian Diagonal (Turkey)

Synoptic animations of internal displacements and deformations of the earth's crust were obtained based on the results of continuous GNSS observations in Eastern Anatolia from 2009 to 2023. The spatiotemporal patterns of the seismic deformation process in connection with the tectonics of the region have been identified. It is shown that dilatation and total shear strains evolve in concert with the migration of the strongest earthquakes Elazig, Elazig-Malatya and devastate Karamanmaraş series. Two years before the occurrence of the devastating earthquakes of 2023, a deficit of internal displacements of GNSS stations developed in the area of their epicenters. The conducted research suggests that the strongest events of 2009-2023 are connected by a unitary seismic deformation process. The most important action in this case is the SW movement of the Anatolian block as monolithic element. In the development of movements and deformations, a flow of increasing stresses is observed in the direction from Karliova Triple Junction to the SW to the area of the strongest seismic events on 02.2023. It originates east of the Karliova Triple Junction where the Arabian Plate encounters an obstacle. The role of mantle flows in the seismic process is assessed

Cyclic behavior of dual-steel beam-to-column welded flange-bolted web connections

Cyclic loading tests on dual-steel beam-to-column welded flange-bolted web connections were conducted to quantify their moment resistance, plastic deformation and energy dissipation capacities. The test program consisted of five one-sided connection specimens, where Q355 grade beams and Q690 grade columns were used, to study the effects of beam-to-column welded flange connection details and panel zone shear strength on the connection seismic performance. Two types of welded connection details were considered; one was the traditional complete-joint-penetration (CJP) welded connections by use of backing bars, and the other type was those with the bottom backing bar further reinforced by a fillet weld. Three column web thicknesses were designed to arrive at strong, intermediate and weak panel zones, respectively. It was found that the CJP weld with the backing bar reinforced only under the bottom beam flange produced satisfactory performance and accommodated plastic rotations larger than 0.03 rad, while a maximum plastic rotation of 0.04 rad could be developed in the high-strength steel panel zone before fracture occurred. These results evidenced that those dual-steel connections could still sustain high seismic deformation demands.

Seismic Deformations at the Ancient Settlement of Raevskoe and Seismotectonics of the Northwestern Caucasus

Seismic Deformations at the Ancient Settlement of Raevskoe and Seismotectonics of the Northwestern Caucasus

Seismic Deformations in Khudoyar Khan Palace, Kokand, Fergana Valley

Seismic Deformations in Khudoyar Khan Palace, Kokand, Fergana Valley