Search Results (3,221)

Earthquake-induced landslide reactivation poses a sustained hazard for years following major seismic events, yet operational prediction remains constrained by heterogeneous multi-modal data, sparse supervision, and the absence of uncertainty-aware frameworks. This paper presents PIMSEL, a physically guided multi-modal semi-supervised framework for post-seismic landslide reactivation risk assessment. PIMSEL integrates satellite-derived morphological features, precipitation time series, and seismic hazard attributes through four components: entropy-regularized optimal transport for cross-modal semantic alignment without paired supervision; causally constrained hierarchical fusion enforcing domain-consistent modal weighting; scenario-based prototype mutation for semi-supervised learning from sparse expert annotations; and prototype-anchored variational graph clustering that simultaneously stratifies landslides into HIGH, MEDIUM, and LOW risk tiers and produces decomposed aleatoric and epistemic uncertainty estimates for operational triage. The HIGH risk tier operationally corresponds to predicted reactivation, validated against 598 documented reactivation events across 7482 co-seismic landslides from three Sichuan Province earthquake sequences: the 2013 Lushan (Mw 7.0), 2017 Jiuzhaigou (Mw 7.0), and 2022 Luding (Mw 6.8) events. PIMSEL achieves 82.5% reactivation recall and 66.4% precision, outperforming twelve baselines across clustering quality, classification, and uncertainty calibration metrics. Ablation studies confirm that optimal transport alignment contributes the largest individual performance gain. Current limitations include quarterly assessment frequency and dependence on optical imagery under cloud cover, which future integration of real-time meteorological triggers and SAR data should address. Full article

To investigate the influence of ambient temperature variations on the natural vibration characteristics and seismic responses of suspen-dome structures, a 1:20 geometric similarity dynamic scale model was designed using the symmetric suspen-dome roof of the Lanzhou Olympic Sports Center Gymnasium as the prototype. First, white noise excitation tests and seismic simulation tests were performed on the model, and the indoor ambient temperature was measured simultaneously. Subsequently, a corresponding numerical scaled model was developed using the ABAQUS 2024 finite element software, and its temperature was set according to the shaking table test measurements. Modal analysis and seismic time–history analysis were then performed, and the model’s natural frequencies and seismic responses (such as acceleration, displacement, and internal force) were compared with the shaking table test results, thereby validating the accuracy of the numerical model and confirming that the modeling approach reliably reproduces the natural frequencies and seismic responses measured in the tests. Finally, the ambient temperature of the numerical model was set according to the historical temperature data for Lanzhou. A comparative analysis was performed to examine the variations in the natural vibration characteristics and seismic responses of the suspen-dome structure under different temperature conditions. The result shows that, as the ambient temperature increases from −30 °C to 60 °C, the natural frequencies of the suspen-dome structure decrease by up to 21.8% (e.g., the third-order frequency drops from 9.423 Hz to 7.734 Hz), with low-order natural frequencies being the most significantly affected. Furthermore, under both unidirectional and three-dimensional earthquake excitations, the peak seismic responses increase markedly: acceleration increases by up to 35.5%, displacement increases by up to 88.3%, and internal force in critical members increases by up to 68.9%. Notably, structural members experiencing higher internal force responses demonstrate greater sensitivity to ambient temperature changes. These findings indicate that ambient temperature variation significantly reduces structural stiffness and amplifies seismic responses, providing a valuable reference for the seismic performance evaluation and safety design of suspen-dome structures in regions with large annual temperature fluctuations. Full article

One-way joist slab floor systems are commonly favored in modern residential building applications due to their efficiency in architectural and structural design processes. However, a significant number of such buildings experienced heavy damage or collapse mechanisms during the catastrophic earthquakes in Türkiye since they are more vulnerable due to some uncertainties in the design and construction stages. In this regard, although well-known seismic codes such as Eurocode, IBC, and ASCE do not impose additional requirements for the design of structural systems with joist slabs, the seismic codes of some Mediterranean basin countries regulate the ductility levels, use of shear walls, and member/system-based specific requirements. In the present study, the impact of shear wall quantity on the seismic behavior of reinforced concrete buildings with one-way joist slabs was investigated in five-story structural systems, which were basically similar in terms of the slab properties and layout but have different overturning moment ratios (α_M = 0.75, 0.60, 0.45, 0). In this context, a total of 88 bi-directional nonlinear time history analyses were conducted on four structural systems, which were highly representative of buildings in the earthquake zones of Türkiye, under real earthquake ground motions. Hence, the seismic behavior demands—including story displacement, inter-story drift and plastic deformations, distributions of plastic hinges, and member-based performance levels—were discussed by the overturning moment ratio that is directly associated with the shear wall quantity in the system. It can be concluded that when these buildings are jointly designed with the shear walls and frames of a high ductility level—through the capacity design principles—the stipulated performance objective can be successfully achieved. While the shear wall quantities ranging from 0.45 to 0.75 did not have a significant impact on the member-based damage across all floors, the frame-only system was found to be inadequate for controlling the lateral deformations due to insufficient stiffness under design-based seismic events. Full article

Reservoir characterization of the Abu Roash “G” (AR/G) Member in the Karama Field, Abu Gharadig Basin, Western Desert of Egypt, is complicated by structural deformation, facies variability, and lithologic heterogeneity, which introduce uncertainties in reservoir evaluation and hydrocarbon estimation. This study aims to provide a comprehensive reservoir assessment through an integrated three-dimensional (3D) static modeling workflow. Well-log data from four wells were combined with the interpretation of seventeen seismic lines to construct structural, stratigraphic, and petrophysical models of the AR/G reservoir. The results indicate that reservoir thickness ranges from 9 to 14 ft and is structurally controlled by nine normal faults forming a horst–graben configuration that significantly influences compartmentalization and hydrocarbon distribution. Petrophysical modeling reveals favorable reservoir quality, with effective porosity ranging from 14% to 20%, an average shale volume of approximately 19%, and hydrocarbon saturation averaging 56%. Two prospective zones were identified, with estimated original oil in place (OOIP) of 10.76 MMSTB and 3.23 MMSTB, respectively, representing recoverable volumes within structurally defined closures rather than the entire field volume. The model also explains the relatively poor performance of Karama-5 and Karama-11 wells due to their peripheral structural positions outside the main closures and their higher water saturation (44–53%). These findings demonstrate that integrated structural and petrophysical modeling improves reservoir understanding and helps identify optimal drilling targets in structurally complex reservoirs of the Abu Gharadig Basin and comparable North African settings. Although the estimated volumes correspond to relatively small accumulations, they are considered economically viable within mature basins such as the Abu Gharadig Basin, where existing infrastructure and optimized development strategies enable efficient exploitation of marginal reserves. Full article

In tunnel engineering, the integration of aseismic materials and structural designs has become a prevalent strategy to reduce earthquake-induced damage. However, previous studies on the seismic performance of tunnel structures predominantly employed deterministic methods, overlooking the spatial variability of the surrounding rock mass. This oversight often leads to an overestimation of structural performance, posing potential risks to the project. This study develops a probabilistic framework based on random field theory to evaluate the aseismic performance of tunnel linings incorporating a rubber–sand–concrete (RSC) constrained damping layer. The analysis systematically evaluates the aseismic performance of RSC across varying peak ground acceleration (PGA) levels and tunnel depth conditions. The findings are compared with results from traditional deterministic approaches. The probabilistic analysis indicates the following: (1) a reduction of approximately 70% in the dispersion of maximum principal stresses across various PGAs; (2) a decrease in RSC’s aseismic performance with greater burial depths, though it remains substantial overall, and (3) a reduction in the failure probability from 31.8% to 16.3% at PGA = 1.2 g. Furthermore, deterministic methods tend to produce overly optimistic estimates of tunnel aseismic performance, highlighting the need for probabilistic analysis. Full article

Dampers are key energy-dissipating components in structural seismic systems. They can effectively dissipate seismic energy, control structural dynamic responses, and mitigate damage to primary structural members. Thus, they play an important role in improving structural seismic resilience and mitigating seismic hazards. By integrating multiple units with different yield thresholds or energy-dissipating mechanisms, multi-stage energy-dissipating dampers realize sequentially activated energy dissipation under varying seismic intensities and spectral characteristics. They broaden the energy dissipation range under varying seismic intensities and enhance cyclic stability and fatigue resistance. They provide an effective technical approach to overcome the inherent limitations of traditional single-stage dampers, such as insufficient energy dissipation capacity and poor cyclic fatigue performance. This study systematically reviews the recent research progress on multi-stage energy-dissipating dampers, focusing on the structural configurations and seismic performance studies of four typical types: stage-yielding metallic dampers, stage-friction dampers, metal-friction hybrid dampers, and metal-viscoelastic hybrid dampers. Relevant numerical simulation and experimental research results are summarized, and the key issues that require further in-depth exploration in this field are prospected. Full article

Impulsive alpha (α)-stable noise, characterized by heavy tails and intense outliers, is a key ingredient in simulating financial, medical, seismic, and digital communication technologies. It poses versatile challenges to conventional machine learning (ML) algorithms in predicting noise parameters for multidisciplinary artificial intelligence (AI)-embedded devices. In this study, we adopted a two-phase methodology to investigate the complexity and performance of supervised ML algorithms while classifying impulsive noise parameters. We generated synthetic datasets of α-stable noise distributions for experimentation in a controlled environment. It was followed by experimental evaluation to derive the complexity and performance of ML classifiers—k-nearest neighbors (KNN), Support Vector Machine (SVM), Naïve Bayes (NB), Decision Tree (DT), and Random Forest (RF). Moreover, we employed a very high channel noise level of −15 dB in the test datasets to ensure that the derived analysis applies to real-world devices. The results demonstrate the high performance of DT and RF in structured binary classification of the α regime and the sign of skewness, while incurring satisfactory computational costs. However, SVM and kNN are comparatively more robust for multi-class classification, albeit with higher memory and training costs. On the contrary, NB fails to address the skewed and impulsive behavior of α-stable noise. We observed that even the most effective classifiers struggle to achieve perfect accuracy in multi-class classification. Overall, the experimental results reveal significant trade-off relationships between the complexity and performance of ML classifiers. Conclusively, simple models are well-suited for coarse-grained tasks, such as α-approximation and sign-of-skewness classification. In contrast, sophisticated models can be deployed to predict noise parameters to some extent. Our study provides a clear set of trade-offs for future applied AI devices that address adversarial and impulsive noise. Full article

This study presents an experimental investigation into the repair and seismic performance enhancement of earthquake-damaged reinforced concrete (RC) frame structures using high-strength cement mortar and viscous dampers. A 1/4-scale, four-story RC frame model—designed according to a seismic fortification intensity of 8 degrees (corresponding to 0.2 g PGA in China’s seismic code)—was subjected to shaking table tests under increasing levels of artificial seismic excitation. Following the first round of loading, the damaged structure was repaired using high-strength mortar infill, and 12 viscous dampers were installed for seismic upgrade. The second round of identical seismic loading was applied to evaluate the effectiveness of the repair strategy. Comparative analysis of structural responses before and after repair reveals that the combination of high-strength mortar and viscous dampers improved damping capacity. The initial natural frequencies of the repaired structure increased by 6% (X) and 24% (Y), and damping ratios rose—reaching 12.75% and 10.78% under rare ground motions (1.34 g). Peak acceleration and inter-story drift ratio (IDR) were effectively reduced under moderate seismic levels, although some increase in IDR was observed at higher intensities, all drift values remained within the seismic code limits. The viscous dampers significantly altered the inter-story deformation mechanism, reducing the deformation concentration factor (DCF) of the frame structure and resulting in a more uniform distribution of story drifts. In addition, the energy dissipation capacity of the dampers increased progressively with the intensity of seismic excitation. The results validate the feasibility and efficiency of integrating viscous dampers with high-strength mortar for seismic repair and retrofitting of RC frame structure. Full article

On 6 February 2023, Türkiye was struck by two devastating earthquakes with moment magnitudes of 7.8 and 7.6, causing severe damage to numerous tall reinforced concrete buildings and emphasizing the need for improved seismic design strategies. This study investigates the seismic response of a representative high-rise reinforced concrete building by systematically varying the shear wall area-to-floor area ratio, a key parameter directly influencing lateral stiffness and overall stability. Utilizing a solid modeling approach and incorporating three-directional seismic records, this research provides detailed insights into displacement behavior beyond conventional frame-based analyses. Focusing on Adana, a major urban center with a significant concentration of tall buildings and notable seismic risk, three design scenarios with shear wall ratios of 1.14%, 1.54%, and 2.1% were examined. The results demonstrate that increasing the shear wall cross-sectional area compared to the building plan area significantly reduces lateral and vertical displacements, with the most pronounced improvement observed when moving from 1.14% to 1.54%. Further increase to 2.1% provides additional enhancement in seismic performance. This study suggests that adopting a minimum shear wall area-to-floor area ratio of at least 2% along each principal direction (resulting in a total combined ratio of approximately 4% for the building) can substantially improve seismic resilience and mitigate collapse risk in tall structures. Importantly, the shear wall ratios were considered separately for each principal direction, with the total combined ratio doubling, highlighting the need for balanced wall distribution in both directions. Full article

In this paper, a hidden ring beam (HRB) joint suitable for steel-tube-reinforced concrete (ST-RC) composite columns is proposed. The seismic performance was evaluated experimentally by hysteresis loading tests on reinforcement anchorage construction and reinforced concrete (RC) slabs, which was evaluated by several indices to assess the strength, ductility, stiffness degradation and energy dissipation capacity. The results showed that the HRB joints have reliable seismic safety performance. The ultimate failure of all the specimens occurred in the plastic hinge regions of the RC beams. The specimens with different reinforcement anchorage construction methods exhibited excellent anchorage performance, maintaining effective anchorage between beam longitudinal bars and ring bars under cyclic loading. The RC slab increased the joint strength and the initial stiffness, with only a reduction in the ductility coefficient, and the average equivalent viscous damping coefficient reached 0.155. In addition, a joint numerical model was established, and the accuracy was validated against the test results, with the predicted strength differing from the test results by no more than 6%. A parametric analysis using numerical simulations revealed that the ring–longitudinal ratio, bearing stirrup diameter, RC slab constraints and axial load ratio were critical factors influencing the seismic performance of the joints. On the basis of the results of the parametric analysis, a moment capacity calculation method is proposed for HRB joints, providing a practical reference for seismic design in engineering applications. Full article

Modern performance-based bridge design seeks to control damage in specific failure modes in order to balance safety and economy, particularly in high-seismic regions where inelastic and ductile deformation is expected to occur, both in the structure and soil, allowing potential reduction in seismic demand through fuse elements. In short-span bridges, abutments strongly influence longitudinal response, whereas transverse performance depends largely on seismic components such as shear keys and other energy-dissipation devices. Thus, performance assessment requires explicit representation of their hysteretic behavior. This study presents a numerical evaluation of the damping provided by common elements in typical bridge systems, using as reference damage observations from bridges affected by recent interface earthquakes in Mexico. Three-dimensional finite-difference models were developed, and nonlinear response-history analyses were performed to simulate ductile behavior and energy dissipation. The Sig3 hysteretic model available in FLAC^3D was used for abutments and foundation soils, while shear keys were represented as nonlinear springs. The results established a relationship between plastic deformation and energy dissipation, showing that incorporating the hysteretic behavior of both soil and sacrificial structural components enhanced the seismic bridge performance assessment, and led to more reliable and cost-efficient designs when inelastic deformation capacity was explicitly included in the numerical simulations. Full article

Radon has long been investigated as a potential earthquake precursor, yet its interpretation remains challenged by meteorological, hydrological, and instrumental variability that can generate apparent departures unrelated to tectonic processes. This review synthesises how artificial intelligence is being applied in radon-based earthquake precursor research, with particular emphasis on anomaly detection and the evaluation of radon seismicity associations. Following a PRISMA-guided workflow, Scopus and the Web of Science Core Collection are searched and screened for eligibility, yielding 26 journal articles, most of which are concentrated in a limited number of tectonically active regions. Across the reviewed literature, a consistent pattern emerges: AI is used primarily to model the expected radon background, while candidate precursors are identified mainly through threshold-based indices derived from residuals or concentration ratios rather than through explicit earthquake-probability outputs. Although pre-seismic departures are reported repeatedly, this review shows that the evidence base remains constrained by heterogeneous operational definitions of anomaly, strong methodological variation across studies, a predominant emphasis on background goodness-of-fit instead of alarm-level performance, and limited use of time-ordered validation. These findings highlight both the promise and the current limitations of AI-enabled radon analysis. The main contribution of the field so far is not direct earthquake prediction but a more structured framework for separating potential tectonic signals from non-seismic variability. In this sense, the review provides an important methodological synthesis for future research and shows that more reproducible and operationally useful radon monitoring will depend on clearer anomaly definitions, stronger confounder control, more rigorous temporal validation, and more standardised performance reporting. Full article

Among the most critical structural deficiencies observed in existing reinforced concrete (RC) buildings worldwide are inadequately detailed beam–column joint regions, often constructed without reinforcement. Despite extensive research, the numerical modeling of these critical components still remains a major challenge, as a robust and universally accepted modeling framework has yet to be established, especially when extensive nonlinear analyses have to be performed. This study specifically addresses how joint reinforcement detailing governs the transition between flexure-dominated and shear-dominated joint behavior in non-ductile exterior sub-assemblages, and evaluates whether and how a simplified macro-model can reliably reproduce these mechanisms at full scale. The seismic behavior of exterior RC beam–column joints without adequate transverse reinforcement was first investigated herein through a full-scale experimental program. Five sub-assemblages were tested under quasi-static cyclic loading with increasing displacement history. They mainly differ for beam and column longitudinal reinforcement amount and joint panel (light or null) reinforcement layout, with equal geometric and material properties. The experimental results are first investigated in terms of global response, damage evolution, and energy dissipation capacity, comparing their seismic performance with varying beam or joint reinforcement. Then, nonlinear analyses were carried out by using a computationally efficient macro-modeling strategy in the OpenSees platform to numerically reproduce the observed response. The joint panel behavior was idealized through an empirical quadrilinear rotational spring, whereas flexural and fixed-end-rotation contributions are mechanically defined. The simulations reproduced the global load–drift envelopes, stiffness deterioration, and post-peak softening branch with satisfactory accuracy, although some discrepancies can be observed in the pinching effect. Nevertheless, the comparison between experimental and full-scale numerical results confirms that the adopted model provides reliable predictions of the cyclic response of non-ductile RC joints, also resulting in suitable solutions for extensive analyses as required, for example, for large-scale studies. Full article

Processed parameters from sensors located on seismically isolated buildings (maximum acceleration, spectral acceleration and oscillation periods) are compared against free-field ground motion to evaluate the improvement in seismic response for these buildings. The study is carried out for three structures in Bucharest, the capital city of Romania. The data used in this research correspond to moderate magnitude earthquakes, 4.2 ≤ M_W ≤ 5.5 generated from the Vrancea-intermediate-depth seismic area, with focal depths greater than ~90 km. The methodology helps to evaluate amplification/reduction in the seismic motion, and confirmed that base-isolation devices reduce the seismic parameters’ amplitudes of the structure directly above the isolating layer. The effectiveness of the base-isolation technique is further assessed by comparing the amplitude of the seismic parameters recorded under and above the earthquake protection devices. The results show a clear decrease in the values right above the isolating system, supporting the efficiency of base-isolation systems. The outcomes provide necessary empirical data for refining seismic design and improving the resilience of critical structures. The work contributes to the mitigation of the seismic risk in the city area, thus targeting a more resilient urban community and sustainable city through implementation of modern base-isolation systems for the retrofitting of vulnerable buildings exposed to a high risk of seismic hazards. Full article

This study re-examines two geologically and geotechnically similar geosynthetic-reinforced soil walls with modular block facings (GRS-MBs) that exhibited markedly different seismic performances during the 1999 Chi-Chi earthquake (M_L = 7.3). Integrating a multi-wedge failure mechanism that captures soil–facing–reinforcement interactions with a nonlinear hyperbolic soil model representing shear stress–displacement behavior along the slip surface, the Force–equilibrium-based Finite Displacement Method (FFDM) provides consistent and robust displacement evaluations over a wide range of input seismic inertial forces. A systematic sensitivity investigation confirms that the FFDM framework responds to parameter variations in a physically meaningful manner, and that displacement predictions remain stable with respect to reasonable uncertainties in soil, reinforcement, and facing properties. The analysis clarifies why two similar GRS-MBs responded so differently during strong shaking and demonstrates the broader applicability of FFDM for displacement-based seismic assessment, including under shaking levels (e.g., k_h ≈ 0.3) that would drive conventional limit–equilibrium calculations to F_s < 1.0, a physically impossible state requiring shear resistance greater than the soil’s ultimate strength. A comparative evaluation of seismic displacement predictions using the Newmark method and FFDM shows that FFDM successfully generates displacement-based seismic resisting curves and reproduces field-observed displacements. In contrast, the Newmark method yields order-of-magnitude variability in predicted movements and may be unsuitable for displacement-sensitive engineered slopes where deformations on the order of several 10⁻³–10⁻² m are practically significant. For interaction-rich GRS-MBs with high values of k_hc, beyond the predictive capability of Newmark’s equation, FFDM offers a practical and physically grounded tool for seismic displacement assessment of reinforced soil structures. Full article