Search Results (1,091)

The Hisayamada Dam (22.5 m high, 75.4 m long), constructed in 1924 as a water supply facility, is a masonry arch–gravity concrete dam with a slender arch shape. Although it was the first theoretically designed arch-type dam in Japan, seismic forces were not considered at the time of construction. This study evaluates its seismic performance using a three-dimensional (3D) dynamic Finite Element Method (FEM) in accordance with current Japanese governmental guidelines. A detailed 3D model incorporating the dam body, surrounding topography, foundation, and reservoir was developed, and expected earthquake motions in three directions were applied simultaneously. The analysis showed that localized tensile stress exceeding the tensile strength occurred near the upstream heel of the dam base. However, these stress concentrations were limited to small regions and did not form continuous damage paths across the dam body. Based on the linear dynamic analysis and engineering judgment, the overall structural integrity and water storage function of the dam are considered to be maintained. Additional analyses were conducted by varying the elastic modulus of the foundation rock and dam concrete to clarify the influence of material stiffness on seismic response and stability. Full article

The Xiannüshan Fault Zone, located in the southwestern part of the Huangling Anticline within the Three Gorges Reservoir area of Hubei Province, is one of the largest and most complex faults in the region. The geological structures of its different segments vary significantly. Previous studies have primarily focused on the northern segment and often relied on single geophysical methods, which are insufficient for detailed characterization of the entire fault zone. Based on existing geological data, field reconnaissance results, and the geological characteristics of different segments of the fault zone, we employed multiple geophysical methods for a varied investigation: shallow seismic reflection in the northern segment; a combination of waterborne seismic exploration and microtremor survey in the middle segment; and high-density resistivity in the southern segment. The integrated approach revealed the spatial extent, fault geometry, and activity characteristics of each segment, confirming that the Xiannüshan Fault Zone is a pre-Quaternary structure dominated by thrusting. The findings provide a critical scientific basis for regional seismic hazard assessment and disaster mitigation planning, while also establishing a technical framework with significant practical application value for detailed fault characterization in geologically complex environments. Full article

In the field of earthquake-resistant design, there is an increasing emphasis on evaluating buildings as integrated systems rather than as assemblies of independent components. Hybrid wall systems based on structural steel and reinforced concrete offer a promising alternative to existing approaches by combining the stiffness and toughness of concrete with the ductility and flexibility of steel, which enhances resilience and seismic performance. The objective of this scientific study is to obtain preliminary analytical estimates of the earthquake response of a prototype hybrid steel RC coupled wall building that is being developed as part of a joint research program between the National Center for Research on Earthquake Engineering (NCREE) and New Zealand’s Centre for Earthquake Resilience (QuakeCoRE). Nonlinear response history analyses were carried out on the prototype building, using scaled ground motions and nonlinear hinge properties assigned to the primary lateral force resisting elements to replicate the expected inelastic behavior of the hybrid system. The results were used to evaluate story drift demands, deformation patterns, coupling beam behavior, and buckling restrained brace behavior, providing a system-level perspective on the expected earthquake performance of the proposed hybrid wall system. To deepen the current experimental understanding of the seismic behavior of the proposed hybrid structural system, a large-scale shaking table test is planned at NCREE as the next stage of this collaborative research. Full article

Soil liquefaction remains a critical geotechnical hazard during earthquakes, posing significant risks to infrastructure and urban resilience. Traditional empirical methods, while practical, often fall short in capturing complex parameter interactions and providing interpretable outputs. This study presents an interpretable machine learning (IML) framework for soil liquefaction assessment using Rough Set Theory (RST) to generate a transparent, rule-based predictive model. Leveraging a standardized SPT-based case history database, the model induces IF–THEN rules that relate seismic and geotechnical parameters to liquefaction occurrence. The resulting 25-rule set demonstrated an accuracy of 86.2% and strong alignment (93.8%) with the widely used stress-based semi-empirical model. Beyond predictive performance, the model introduces scenario maps and parameter interaction diagrams that elucidate key thresholds and interdependencies, enhancing its utility for engineers, planners, and policymakers. Notably, the model reveals that soils with high fines content can still be susceptible to liquefaction under strong shaking, and that epicentral distance plays a more direct role than previously emphasized. By balancing interpretability and predictive strength, this rule-based approach advances site-adaptive, explainable, and technically grounded liquefaction assessment—bridging the gap between traditional methods and intelligent decision support in geotechnical engineering. Full article

Accelerographs are essential instruments for quantifying strong ground motion, serving as the foundation of modern earthquake engineering. In Peru, the first accelerographic station was installed in Lima in 1944; since then, various institutions have promoted the expansion of the national network. However, this network’s spatial coverage and instrumentation remain insufficient to properly characterize strong motion and support seismic risk reduction policies. In this context, the KUYUY accelerograph is presented as a low-cost, low-noise device equipped with real-time telemetry and high-performance MEMS sensors. Its interoperability with the Intelligent Automatic Processing System (SIPA) enables real-time monitoring and automated signal analysis for seismic microzonation studies and rapid damage assessment, contributing to seismic risk reduction in Peru. The validation process included static gravity calibration, field comparison with a reference accelerograph, and an initial deployment in Lima and Yurimaguas. The results demonstrate the proposed accelerograph’s linear response, temporal stability, and amplitude consistency with respect to high-end instruments, with differences below 5–10%. Full article

This paper presents the outcomes of an extensive experimental investigation on the seismic performance of an innovative exoskeleton retrofitting system, developed as part of the ERIES-RESUME project. The proposed system integrates laminated timber and aluminium components to enhance the structural resilience of existing reinforced concrete (RC) buildings, while also offering the potential for thermal upgrading. Two identical 1:3 scale RC models, representing typical non-ductile structures, were tested on a shaking table at the IZIIS Laboratory of the Institute of Earthquake Engineering and Engineering Seismology in Skopje. The first model, initially unstrengthened, was subjected to seismic loads until significant structural and infill-wall damage was reached. Following appropriate repairs, the exoskeleton was applied, and the model was retested. The second model was equipped with an exoskeleton from the outset. Test results demonstrate significant improvements in seismic performance, including increased stiffness, reduced interstory drifts, reduced acceleration amplification, and reduced infill wall damage. The study confirms the feasibility and effectiveness of the proposed exoskeleton system as a practical solution for retrofitting vulnerable reinforced concrete buildings. Full article

To investigate the performance of horizontally reinforced composite foundations in resisting surface rupture of normal faults, this study designed and conducted a series of physical model tests. A systematic comparative analysis was performed on the fracture resistance of sites with three-layer sand, five-layer sand, and three-layer clay geogrid horizontally reinforced composite foundations under 70° normal fault dislocation. The results indicate that significant changes in earth pressure serve as a precursor indicator of fault rupture, and their evolution process reveals the internal energy accumulation and release mechanism. Increasing the number of geogrid layers significantly enhances the lateral confinement of the foundation, resulting in a narrower macro-rupture zone located farther from the structure in sand sites, and promotes the formation of a step-fault scarp deformation mode at the surface, which is more conducive to structural safety. Under identical reinforcement conditions, the clay site exhibited comprehensively superior fracture resistance compared to the sand site due to the soil cohesion and stronger interfacial interaction with the geogrids, manifested as more significant deviation of the rupture path, and lower microseismic accelerations and structural strains transmitted to the building. Comprehensive analysis confirms that employing geogrid-reinforced composite foundations can effectively guide the surface rupture path and improve the deformation pattern, representing an effective engineering measure for mitigating disaster risk for buildings spanning active faults. Full article

Tsunamis and submarine earthquakes pose severe risks to coastal regions, demanding rapid and reliable monitoring systems. While the Deep-ocean Assessment and Reporting of Tsunamis (DART) system has been globally deployed, its dependence on pressure sensors and one-to-one communication limits its applicability to the Korean East Sea. This paper introduces the Korean Tsunami and Earthquake Monitoring System, which integrates seafloor seismometers and proposes a dedicated Medium Access Control (MAC) protocol optimized for multi-node underwater acoustic communication. The study performs a comprehensive analytical derivation of closed-form expressions for channel utilization and energy consumption under diverse node configurations and acoustic conditions. The analytical results confirm that the proposed MAC protocol maintains stable performance, supports multi-node operation, and enables long-term monitoring within the limited energy budget of underwater devices. The derived results also provide practical design implications for underwater network planning, including guidelines on node placement, frame duration, and control packet timing for efficient data delivery. Although empirical validation remains as future work, the findings establish theoretical benchmarks and engineering insights for the design of next-generation underwater monitoring systems tailored to Korean coastal environments. Full article

This study presents a framework for assessing the resilience of steel special moment-resisting frame (SMRF) buildings under sequential earthquake–flood hazards. Surrogate models, including a stacked attention-based LSTM network (Stack-AttenLSTM) and CatBoost, are developed to predict key engineering demand parameters (EDPs), particularly maximum inter-storey drift ratios (MIDRs), avoiding the need for computationally expensive nonlinear time history analysis (NLTHA). The predicted EDPs are integrated with the FEMA P-58 methodology to estimate repair costs and durations, while the REDi framework is used to capture recovery delays and functionality loss. A two-storey code-compliant SMRF building is evaluated under a design-basis earthquake (DBE) with and without a subsequent 4.0 m flood. Results show that the combined hazard nearly doubles repair costs (from 0.33 to 0.77 of replacement value), increases downtime from 194 to over 411 days, and reduces the resilience index (R_i) from 0.873 to 0.265. These findings highlight the severe impacts of cascading multi-hazard events and the need to extend performance-based design toward resilience-focused strategies. The proposed surrogate-based framework provides a practical tool for evaluating multi-hazard risks and guiding the design of more resilient structures. Full article

L-shaped concrete-filled steel tubular (CFST) columns have attracted increasing attention in recent years due to their favorable seismic performance and their ability to reduce column protrusions into interior wall surfaces. Existing studies on L-shaped CFST columns have mainly focused on a specific cross-section form, and the mechanical behavior of L-shaped CFST columns with different limb length ratios and inter-limb angles has not yet been sufficiently investigated. To further examine the axial compressive performance of L-shaped CFST columns, this study designed and tested eight L-shaped CFST columns by considering the cross-section form, limb-length ratio, and inter-limb angle as key parameters. In addition, a simplified formula for predicting the axial load capacity of L-shaped CFST columns was proposed based on the unified theory. The test results indicated that the cross-section form significantly affects both load-carrying capacity and ductility. For the equal-limb specimens, the peak load of the C-type specimen was 8% and 9% higher than that of the A-type and B-type specimens, respectively, whereas the displacement ductility coefficient of the A-type specimen was 48% and 47% higher than that of the B-type and C-type specimens, respectively. Compared with the unequal limb specimens, the equal limb specimens exhibited an increase in peak load of more than 20%; moreover, the displacement ductility coefficients of the A-type and B-type specimens increased by 48% and 61%, respectively. Increasing the inter-limb angle enhanced the peak load but reduced the ductility, and it led to a gradual shift in the failure mode from local buckling of the steel tube to overall bending. The findings of this study contribute to a more comprehensive understanding of the mechanical behavior of L-shaped CFST columns and can provide reference for their design and optimization. Full article

Bridge Health Monitoring (BHM) systems generate nonstationary time-series data that pose challenges for accurate structural state prediction. This study proposes a novel neural network-based method for predicting bridge states, the Temporal Multi-Scale Convolutional Neural Network (T-MSCNN) to enhance the prediction of dynamic strain parameters, which directly reflect structural stress states. The T-MSCNN integrates multi-scale convolutional layers for local feature extraction and gated recurrent units (GRUs), by using the Convolutional Neural Network (CNN) model and the Gated Recurrent Unit (GRU) model to address the intricacies of the nonstationary BHM data. Validated with real strain data from the Qijiang River Bridge in China, the model demonstrated superior performance over traditional models (HA, ARIMA, SVR) and standalone deep learning models (CNN, GRU), achieving reductions in prediction error by Root Mean Square Error (RMSE) method—up to 77.7%, compared to the ARIMA model and consistently improving even over the strong GRU baseline. The perturbation analysis confirms its robustness under noise interference. The T-MSCNN provides a reliable data-driven framework for structural health diagnostics, with potential applicability to other fields involving nonlinear spatiotemporal data analysis. Full article

The long-term safety of concrete shaft walls in deep mines faces severe challenges from the coupled effects of stress, chemical erosion, and dynamic disturbances. This study conducted coupled loading and sulfate erosion tests on concrete and investigated its dynamic response using drop-weight impact tests. The failure modes, impact force time-history curves, and strain time-history curves of concrete under different erosion ages and load levels were analyzed. The SEM observations revealed the microstructure of the concrete. Results indicate that increasing drop height exacerbates specimen failure and elevates peak impact force and strain, while simultaneously shortening the impact duration. Compared to SL20, SL40 exhibited lower peak impact force and higher peak strain under long-term combined loading and sulfate erosion. This reveals that larger loads accelerate internal damage within concrete under erosive conditions. This study provides theoretical and experimental bases for the long-term safety and impact resistance of well wall concrete. Full article

The purpose of this study is to determine the effect of the angle of seismic incidence on the fragility of regular pile-supported wharves. The investigation is performed by selecting the displacement demand at the deck level of critical piles located at the segment ends as the engineering demand parameter, in accordance with the current seismic design practices. Then, probabilistic seismic demand analyses are conducted on nine pile-supported wharf structures with 80 pairs of bi-directional earthquake ground motion records to determine the optimal probabilistic seismic demand models. During demand analyses, both the accurate procedure for addressing the effect of bi-directional earthquake loading and the correspondingly simplified procedures in current design practices are included. Thus, seismic fragility curves of wharves are developed with respect to both the optimal intensity measure (IM) and incident angles. The results highlight that the directivity of ground motion excitation may have a minor impact on the fragility of wharves subjected to bi-directional ground motions. Consequently, probabilistic seismic demand analyses can be performed by simultaneously applying bi-directional ground motions only along the principal axes of the wharves. Meanwhile, the resultant displacement demand under simultaneous seismic excitation can be approximately determined by combining the displacement demand resulting from 100% of the loading in one direction with the corresponding displacement demand from 30% of the loading in the perpendicular direction. This simplified procedure for demand analyses can also yield satisfactory results in fragility analysis. Full article

Although the dynamic response of orthotropic materials under uniaxial impact loading has been extensively studied, their behavior under multiaxial stress states, which more accurately represent real-world blast and impact scenarios, has received limited attention. To address this gap, this study employed a self-developed biaxial impact testing apparatus to systematically investigate the dynamic mechanical behavior of beech wood, a typical orthotropic material, under three biaxial loading configurations: radial-tangential, radial-longitudinal, and tangential-longitudinal. By combining theoretical derivation with experimental data, it systematically examines stress wave propagation characteristics, strain rate effects, and anisotropy evolution under different loading paths. The results reveal that beech wood exhibits significantly distinct dynamic responses along different material orientations, with a consistent strength hierarchy: longitudinal > radial > tangential. Biaxial loading notably enhances the equivalent stress–strain response and alters the deformation mechanisms and energy absorption behavior. Furthermore, lateral confinement and multiaxial stress coupling are identified as critical factors influencing the dynamic performance. This study provides the first systematic revelation of the strain rate strengthening mechanisms and wave propagation characteristics of orthotropic materials from the perspective of multiaxial dynamic loading, thereby offering theoretical and experimental foundations for developing advanced dynamic constitutive models suitable for complex impact conditions. These findings provide important guidance for the design and evaluation of lightweight impact-resistant structures in fields such as aerospace and protective engineering. Full article

The 17 November 2023 M_W 6.8 earthquake located offshore of Southern Mindanao, Philippines, triggered soil liquefaction along the lowlands of the Sarangani Peninsula. Detailed mapping, geomorphological interpretations, geophysical surveys, comparison with predictive models, and grain size analysis were conducted to obtain a comprehensive understanding of the earthquake parameters and subsurface conditions that permitted liquefaction. Soil liquefaction manifested as sediment and water vents, fissures, lateral spreads, and ground deformation, mainly along landforms with shallow groundwater levels such as river deltas, fills, floodplains, and beaches. In populated areas, ground failure due to liquefaction also damaged some buildings. All these impacts fall within the boundaries of the available liquefaction hazard maps for Sarangani Peninsula and the predictive empirical equations generated by various authors. Simulated peak ground acceleration values also indicate that sufficient ground shaking was generated for the soil to liquefy. Refraction microtremor (ReMi) surveys reveal shear wave velocities ranging from 121 to 215 m/s, which infer the presence of soft and stiff soils beneath the surface, promoting the sites’ potential to liquefy. Grain size analyses of sediment ejecta confirm the presence of these liquefiable sediments from the subsurface, with grain sizes ranging from silt to medium sand. The results of three-component microtremor (3CMt) surveys also show varying sediment thicknesses, which are consistent with the thickness of soft sediment layers inferred by ReMi surveys. The information resulting from this study may be useful for researchers, planners, and engineers for liquefaction hazard assessment and mitigation, especially in the Sarangani Peninsula. Full article