A casualty-estimation framework has been proposed that incorporates building-scale, time-varying occupancy data (considering factors such as size, use, and time of day) into earthquake loss modeling. Information from Seumter building records is combined with KOSIS population data, and HAZUS modules are used to estimate both the baseline population and dynamic occupancy at the building level. Case studies have shown a close alignment with observed data, with no significant model flaws, indicating the framework’s operational readiness. This approach moves beyond broad administrative totals to provide micro-spatial resolution suitable for Korea’s rapid seismic attenuation and localized damage patterns. It enables accurate, time-sensitive casualty estimates. The framework is designed to be scalable to include additional data sources, such as mobility, transportation, and activity patterns. It supports effective evacuation and shelter planning, surge capacity management, and prioritization of retrofitting, leading to more efficient resource allocation. Furthermore, the framework provides a consistent method to integrate future data streams and quantify uncertainty without disrupting the core workflow.

Non-seismic-designed reinforced concrete (RC) pier walls often include lap splices in potential plastic hinge regions. This study develops an analytical model to capture the post-yield load–deformation response of lap-spliced RC pier walls subjected to earthquake loading. The parameters of the model were calibrated using experimental results, and linear regression was conducted to propose predictive equations for these parameters. The accuracy of the model was validated by comparing it to the load–deformation responses of specimens not included in the calibration database. Subsequently, the developed model was applied to probabilistic bridge models supported by RC pier walls. A multi-parameter seismic demand model was constructed, taking into account geometric, material, and structural uncertainties, using Lasso regression. This model achieved R² values of 0.73 for in-plane loading and 0.75 for out-of-plane loading. The improvements in performance metrics and the results of the sensitivity analysis emphasize the need to develop a multi-parameter seismic demand model to ensure more reliable seismic demand predictions.

Earthquakes can damage transmission system components, leading to extensive blackouts and disrupting essential societal functions. In urban areas, interruptions in power supply critically impact sectors such as industry, healthcare, and telecommunications, highlighting the need for quantitative and systematic analysis. Most existing research has focused on assessing seismic fragility at the individual facility level, with insufficient probabilistic safety evaluations that consider the connectivity of entire transmission systems. This study aims to quantify the connectivity-based seismic fragility and risk associated with transmission systems in Busan and its neighboring regions, Ulsan and Gyeongnam. To achieve this, a network model of Busan’s transmission system was developed using OpenStreetMap data. Damage probabilities were calculated using seismic fragility curves from HAZUS and reports from the Ministry of the Interior and Safety. Damage state-specific risks were then quantitatively assessed by combining these fragility values with Busan’s seismic hazard curves. The results showed High Confidence and Low Probability of Failure values ranging from 0.049 g (Slight) to 0.273 g (Complete), with median fragility values ranging from 0.143 g (Slight) to 0.605 g (Complete). The annual risk for each damage state was determined to be 4.151×10-4/yr, 1.177×10-4/yr, 3.667×10-5/yr, and 9.391×10-6/yr. This research quantitatively assesses the seismic fragility of Busan’s transmission system, providing a practical basis for disaster response strategies and risk-informed decision-making related to regional electric power infrastructure.

대부분의 원전 설비의 내진 해석에는 해석이 비교적 간편하고, 설계에 보수성을 적절히 반영할 수 있어 대부분 기기가 설치된 위치에서의 층응답스펙트럼 혹은 In-structure response spectrum을 이용한 응답스펙트럼 해석을 주로 이용하고 있다. 설비 공급자 는 설계 시방서에 층응답스펙트럼 선도의 형태로 입력 지진파 자료를 받게 되는데, 필요시 이를 바탕으로 인공 지진파을 만들어 해석 혹은 시험을 수행한다. 설계지반응답스펙트럼의 경우 RG 1.60에 주어지고 SRP 3.7.1의 요건에 따라 인공 지진파 시간 이력을 생성하 나, 층응답스펙트럼의 경우 명확은 기준이 없어 이를 따르고 있다. 층응답스펙트럼은 구조물의 동특성이 반영되기 때문에 지반응답스 펙트럼에 비해 형태가 복잡하여 기존의 P-CARES 등의 인공 지진파 생성 프로그램을 이용할 경우 SRP 3.7.1의 요건에 맞는 시간 이력 인공 지진파를 얻기 위해서는 상당한 노력이 필요하다. 본 연구에서는 수치 최적화를 이용하여 복잡한 형태의 층응답스펙트럼이 라도 SRP 3.7.1의 요건 내에서 그 형태를 따르는 인공 지진파 시간 이력을 효율적으로 생성할 수 있는 절차를 개발하였다.

본 연구에서는 TMD 설계 방법에 따른 배관의 지진응답 감소효과를 분석하였다. 구체적으로, 실제 원전 배관에 대한 진동대 시험 결과를 바탕으로 수치 배관 모델을 수립하고 검증하였다. 검증된 배관 모델을 바탕으로 TMD 설치 위치를 결정하고, 여러 가지 방법을 사용하여 TMD 설계값을 도출하였다. 더불어, 본 연구에서는 기존 설계식들을 기하평균한 값을 TMD 설계값으로 활용하였다. 최종적으로, 기존 배관을 기반으로 설계된 TMD가 지진의 무작위성과 지진 및 대상물질의 불확실성 아래에서도 효용성을 검증하였다. 또한, 연구에서 제안한 기하평균 모델을 기반으로 설계된 TMD의 작동성을 확인하였다. 결과적으로, TMD 설계 공식 및 방법에 따른 성능 차이를 비교한 결과, 기하평균 모델의 경우, 기존 설계식들의 특징을 포괄하는 양상이 보였다. 이러한 기하평균 모델은 추후 반복 적인 수치해석을 수행할 때 초기값으로 사용될 수 있을 것으로 보인다. 더불어, 이러한 분석 결과는 향후 원전 배관 계통의 TMD 설계 를 통해 내진 성능을 개선하는 데 유용한 자료로 활용될 것으로 기대된다.

The 2024 Noto Peninsula Earthquake in Japan caused significant damage to wooden structures due to strong ground motion and widespread liquefaction. This study examines the damage patterns observed in wooden houses and analyzes the underlying structural vulnerabilities that contribute to these patterns. Key findings include standard failure modes such as foundation settlement, soft-story collapse, torsional deformation, and joint failure. The evolution of Japan’s seismic design standards has been reviewed, highlighting the importance of balanced wall distribution, reinforced connections, and lightweight roofing systems. Based on field investigations, this study systematically classifies the types of seismic damage in wood structures. It develops a qualitative performance curve that visually illustrates structural behavior in terms of inclination, seismic damage patterns, and repairability. Furthermore, a seismic damage taxonomy is proposed to infer the causes of damage through logical links between observed failure patterns and structural vulnerabilities. This research establishes a practical foundation for the seismic design and retrofit strategies of wood structures, ultimately contributing to the advancement of earthquake-resilient construction practices.

The concept of resilience has gained increasing attention amid growing urbanization and rising vulnerability to infrastructure. While various methodologies exist for evaluating the resilience of lifeline systems, few address the distinct structural features and failure modes of railway networks. This study refines existing approaches by incorporating characteristics unique to high-speed railways, with a focus on two key aspects. First, we define the structure of railway networks by identifying nodes and links, and deriving link-specific resilience criteria based on the fragility characteristics and recovery profiles of their structural components. Second, we utilize real data from the Korean railway system to quantify the performance degradation caused by component failures during seismic events. To assess the framework’s applicability, we use a simplified network and a more complex one integrating Korea’s Honam Line and Honam High-Speed Line. The framework effectively identifies critical scenarios and provides a valuable tool for decision-makers in assessing seismic risk and planning recovery for railway infrastructure.

Seismic design and risk assessment require input ground motions that accurately reflect both the seismic intensity associated with the target hazard level and the regional seismic characteristics of Korea. In this study, a scenario earthquake was defined through seismic hazard deaggregation. Due to the lack of recorded ground motions in Korea for this particular scenario, a finite fault was modeled. Seed ground motions related to the scenario earthquake were generated using the empirical Green’s function method, based on the 912 Gyeongju earthquake. During the spectral matching process, the convergence of the spectrum used for ground motion selection and the target Uniform Hazard Spectrum (UHS) was analyzed. This analysis led to the proposal of specific spectral conditions for selecting ground motions. The final set of input ground motions was then applied in time-history analyses of a nuclear power plant containment structure to assess its seismic response characteristics. The analysis results demonstrate that the proposed ground motion generation procedure applies to the development of ground motions in regions with moderate seismicity.

Existing reinforced concrete building structures have seismically-deficient details on columns and beam–column joints; therefore, accurate modeling of structural behavior is required for reliable seismic performance assessment. This study aims to investigate the differences in dynamic responses resulting from modeling variations through developing four distinct numerical models. Separate models were established to simulate flexural and shear failures of columns and beam–column joints. Using these component-level models, a structural analysis model of the target building was constructed, and nonlinear time-history analyses were performed to evaluate seismic performance. Based on the simulated dynamic behavior of the target building, soft-story mechanisms were identified, and it was identified and confirmed that column behavior plays a dominant role in governing the overall structural response.

This study was intended to compare with seismic fragility assessments for a low-rise RC piloti structure using the Capacity Spectrum Method (CSM) and the Incremental Dynamic Analysis (IDA). Distribution-parameters were estimated using the Method of Moments (MoM) and the Maximum Likelihood Estimation (MLE). For given limit states defined by FEMA 356, two seismic fragility assessments yielded different medians and dispersions: the CSM produced steeper in the slopes of fragility curves with smaller dispersions, whereas the IDA captured wider response scatters and broader dispersions. When fitting the fragility curves, the MLE scheme provided to well match with the empirical cumulative distribution function(CDF) than the MoM scheme, which understated dispersions.

Machine learning (ML) techniques have been increasingly applied to the field of structural engineering for the prediction of complex dynamic responses of safety-critical infrastructures such as nuclear power plant (NPP) structures. However, the development of ML-based prediction models requires a large amount of training data, which is computationally expensive to generate using traditional finite element method (FEM) time history analysis, especially for aging NPP structures. To address this issue, this study investigates the effectiveness of synthetic data generated using Conditional Tabular GAN (CTGAN) in training ML models for seismic response prediction of an NPP auxiliary building. To overcome the high computational cost of data generation, synthetic tabular data was generated using CTGAN and its quality was evaluated in terms of distribution similarity (Shape) and feature relationship consistency (Pair Trends) with the original FEM data. Four training datasets with varying proportions of synthetic data were constructed and used to train neural network models. The predictive accuracy of the models was assessed using a separate test set composed only of original FEM data. The results showed that models trained with up to 50% synthetic data maintained high prediction accuracy, comparable to those trained with only original data. These findings indicate that CTGAN-generated data can effectively supplement training datasets and reduce the computational burden in ML model development for seismic response prediction of NPP structures.

In the United States, seismic design standards are crucial in classifying buildings into Risk Categories I to IV. These categories are based on the buildings' occupancy type and the potential risk they pose to public safety, the protection of human life, and the socioeconomic consequences of structural collapse in the event of an earthquake. As the risk category increases, a higher seismic importance factor and more stringent drift limits are imposed on the respective building. This results in enhanced lateral strength and stiffness of the seismic force-resisting system. This study, which compares the seismic demands of special moment frame buildings assigned to high-risk categories, focusing on static system overstrength, ductility, and collapse risk, provides practical insights for structural engineers and architects. For this purpose, nonlinear static and dynamic analyses are performed to quantify the seismic demands of 18 steel frame buildings assigned to Risk Categories II, III, and IV. The findings indicate that buildings in Risk Category II do not meet the target collapse risk of 1% in 50 years, as specified in ASCE/SEI 7. For buildings in higher risk categories, the equivalent lateral force method for estimating seismic base shear is deemed more effective in ensuring adequate seismic performance.

펄스형 지진이 비펄스형 지진보다 구조물에 보다 큰 손상을 유발하는 것으로 알려져 있다. 펄스형 지진으로부터 속도펄스를 추출 하면 펄스주기를 평가할 수 있는데, 55개의 펄스형 지진기록을 선정하여 펄스 주기를 평가하고 펄스 주기에 따라서 세 그룹으로 구분 하였다. 펄스 주기를 달리하는 따른 세 개의 지진그룹에 대하여 가속도, 속도, 변위에 대한 평균 응답스펙트럼을 비교한 결과, 펄스 주 기와 펄스주기에 대응하는 주기영역에서의 응답스펙트럼은 밀접한 연관성이 있음을 알 수 있었다. 펄스형 지진의 펄스주기가 교량 의 지진취약도에 미치는 영향을 분석하기 위하여, 세 가지 지진그룹의 펄스주기와 유사한 고유주기를 가지는 세 가지 교량모델을 작 성하여 지진취약도 해석을 수행하였다. 교량의 고유 주기와 펄스형 지진의 펄스 주기가 서로 유사할수록, 교량의지진취약도가 증가 함을 알 수 있다. 즉, 두 주기 간의 유사성이 증가할수록, 교량의 비탄성 응답이 증가하며 이에 따른 구조적 손상이 크게 증가한다고 할 수 있다.

The 3T irregular shape structure is used for designing wind loads in high-rise buildings. Among them, the Tapered shape is a shape with a cross-section that changes throughout the entire floor. Recently, various advanced Tapered shapes have been applied, such as having a cross-section that varies only in part of the height or combining different shapes. In this study, an analysis model was selected by applying three types of Tapered part locations(Bottom, Middle, Top) and angles as design variables. Equivalent static seismic loads and historical earthquake records were applied to compare and analyze the seismic response of the Tapered models with regular-shaped models. As a result of the analysis, positioning the partial taper in the middle shows the lowest seismic response. Additionally, a larger taper angle decreased the story drift ratio, top-story displacement, shear wall shear force, and column bending moment, while increasing absolute acceleration and column axial force.

Our study develops a finite element analysis (FEA) model to evaluate the seismic performance of a two-story reinforced concrete (RC) school building and validates it through experiments. We developed a methodology that reflects failure modes from past experiments and validated it by comparing results at both the member (columns) and system (beam-column joints) levels. We created an FEA model for seismic-vulnerable RC moment frames using this methodology. This model incorporates bond-slip effects using three methods: Merged Nodes, Constrained Beam in Solid Penalty (CBISP), and Constrained Beam in Solid Friction (CBISF), which model the interaction between reinforcement and concrete. The approach provides a reliable tool for evaluating seismic performance and improves the accuracy of reinforced concrete frame evaluations.

Most reinforced concrete (RC) school buildings constructed in the 1980s have seismic vulnerabilities due to low transverse reinforcement ratios in columns and beam-column joints. In addition, the building structures designed for only gravity loads have the weak-columnstrong- beam (WCSB) system, resulting in low lateral resistance capacity. This study aims to investigate the lateral resistance capacities of a two-story, full-scale school building specimen through cyclic loading tests. Based on the experimental responses, load-displacement hysteresis behavior and story drift-strain relationship were mainly investigated by comparing the responses to code-defined story drift limits. The test specimen experienced stress concentration at the bottom of the first story columns and shear failure at the beam-column joints with strength degradation and bond failure observed at the life safety level specified in the code-defined drift limits for RC moment frames with seismic details. This indicates that the seismically vulnerable school building test specimen does not meet the minimum performance requirements under a 1,400-year return period earthquake, suggesting that seismic retrofitting is necessary.

A seismic intensity map, which describes ground motion distribution due to an earthquake, is crucial for disaster evaluation after the event. The ShakeMap system, developed and disseminated by the USGS, is widely used to generate intensity maps in many countries. The system utilizes a semi-variogram model to interpolate the measured intensities at seismic stations spatially. However, the default semi-variogram model embedded in ShakeMap is based on data from high seismic regions, which may not be suitable for the Korean Peninsula, categorized as a low-to-moderate seismic region. To address this discrepancy, this study aims to develop the region-specific semi-variogram model using local records and a region-specific ground motion model (GMM). To achieve this, we followed these steps: 1) collected records from significant earthquake events in South Korea, 2) calculated residuals between the observed intensities and predictions by the GMM, and 3) created semi-variogram models using weighted least squares regression to better fit short separation distances for PGA, PGV, SA0.2, and SA1.0. We compared the developed semi-variogram models with conventional models embedded in ShakeMap. Validation tests showed that the region-specific semi-variogram model reduced the mean squared error of intensity predictions by approximately 3.5% compared to the conventional model.

Reinforced concrete (RC) columns exhibit cyclic damage, such as strength degradation, under cyclic lateral loading, such as earthquakes. Considering the cyclic damage, the nonlinear load-deformation response of RC columns can be simulated using a lumped plasticity model. Based on an experimental database, this study calibrates lumped plasticity model parameters for 371 rectangular and 290 circular RC columns. The model parameters for adequate flexural rigidity, plastic rotation capacity, post-capping rotation capacity, moment strength, and cyclic strength degradation parameter are adjusted to match each experimentally observed load-deformation response. We have developed predictive equations that accurately relate the model parameters to the design characteristics of RC columns through regression analyses, providing a reliable tool for engineers and researchers. To demonstrate their application, the proposed and existing models numerically simulate the earthquake response of a bridge pier in a metropolitan railway bridge. The pier is subjected to several ground motions, increasing intensity until collapse occurs. The proposed lumped plasticity model showed about 41% less vulnerable to collapse.