This study establishes a structured development procedure for a non-ergodic ground motion model (GMM) and applies it to Korean seismic records to evaluate uncertainty reduction. The proposed framework includes data screening based on signal-to-noise ratio, residual computation relative to NGA-East predictions, identification of systematic trends, and stepwise correction of site, magnitude, and distance effects. A total of 368 records from 16 earthquakes (Mw ≥ 4.0) observed at 53 stations were analyzed. The residuals exhibited clear VS30-dependent trends, particularly at short periods (–0.2 s). Period-dependent VS₃₀ correction terms were derived through linear regression, with additional corrections for magnitude and distance applied when sufficient data were available. Spectral comparisons for the 2016 Gyeongju and 2017 Pohang earthquakes demonstrated improved agreement after calibration. The stepwise corrections resulted in a consistent reduction of total standard deviation across periods, with the largest decrease observed near 0.1 s. These results indicate that the proposed development procedure provides a practical pathway for transitioning from ergodic to partially non-ergodic modeling and effectively reduces aleatory uncertainty for Korean seismic hazard applications.

This study conducted nonlinear static analyses to evaluate the effect of structural eccentricity on the seismic performance of piloti-type buildings. Analytical models reflecting the actual structural details of buildings acquired and operated by the Korea Land and Housing Corporation (LH) and the Seoul Housing and Communities Corporation (SH) were developed, and eccentricity ratios were considered as key analytical parameters. The effects of eccentricity on structural response were quantitatively assessed through the evaluation of performance points, plastic hinge distribution, axial load sharing ratio, and interstory drift ratio. The analytical results demonstrated that increasing eccentricity caused the performance point to approach the maximum load and concentrated plastic hinges at the ground story, leading to a noticeable degradation in overall seismic performance. Furthermore, when the eccentricity exceeded approximately 8%, the interstory drift ratio at the ground story tended to surpass the allowable limit specified in the national seismic performance evaluation guidelines. Accordingly, maintaining the eccentricity ratio below approximately 5% is suggested as a rational design strategy to ensure stable seismic performance. The findings provide valuable insights for improving seismic performance evaluation methods and design criteria for piloti-type structures.

External steel frame retrofitting effectively enhances the lateral resistance performance of existing reinforced concrete school buildings. However, when column shear failure occurs, ductility capacity is reduced, posing a risk of sudden collapse in high-seismic hazard areas. The purpose of this study is to propose a linear-elastic analysis-based retrofit process to reduce the likelihood of column shear failure and maximize retrofit effectiveness when applying external steel frame retrofitting. To achieve these objectives, a multiple-step process was presented and a case application was performed using quasi-static cyclic loading test results of a school building specimen retrofitted with an external steel frame system. Experimental results showed that strength, stiffness, and energy dissipation were improved by the retrofit system. However, the damage mechanism shifted from beam-column joints to column bases, resulting in reduced ductility capacity due to column shear failure. By applying the proposed process, the lateral stiffness ratio of the external steel frame columns was increased from 0.23 to 0.74, eliminating shear failure in existing reinforced concrete columns and confirming that it can contribute to improving ductility capacity.

유연한 지반 위에 놓인 비정착식 원통형 액체저장탱크의 지진응답을 바닥판의 들림을 고려하여 산정하기 위한 유한요소 해석기법 을 개발한다. 지반-구조물 상호작용력과 저장 액체 동수압력을 재료 및 기하 비선형 거동을 고려한 구조물의 비선형 유한요소 모형과 결합한다. 구조물과 지반 사이의 들림을 모사하기 위해 인장에 대해서는 강성을 무시할 수 있는 비선형 스프링 요소를 사용한다. 개발 된 비선형 유한요소 모델을 사용하여 지진지반운동이 작용하는 액체저장탱크의 지진응답을 정밀히 산정한다. 구조물의 재료 및 기 하 비선형 거동을 고려하면 구조물 벽체의 응력이 크게 증가하여 소성 응답이 증가하지만, 바닥 들림까지 고려하게 되면 구조물 바닥 이 자유롭게 들리게 됨으로써 구조물의 응력과 소성 응답이 크게 감소하게 된다. 그러므로 구조물의 재료 및 기하 비선형 거동 뿐만이 아니라 구조물과 지반 접촉면의 분리(바닥 들림)와 같은 경계 비선형 거동을 엄밀히 고려하여 비정착 유체-구조물-지반 상호작용계 의 지진응답을 정확히 산정해야 할 것이다.

This study proposes a method to improve the seismic performance of a stacked stone pagoda by applying a Ball Vibration Absorber (BVA) with a non-fixed connection. The governing equations of motion were derived by analyzing the structure's primary failure mode under seismic excitation and sliding behavior, and a numerical model was constructed. To verify the model's reliability, a shaking table experiment with a two-layer rectangular block structure was conducted, and the experimental results were compared with numerical simulations. Based on the validated numerical model, both artificial and real earthquake records were used for parametric analyses to determine the optimal design parameters that maximize the damping efficiency of the BVA system. The main findings of this study are as follows. First, when the difference between the rolling path radius and the ball radius is small, the damping performance of the BVA decreases. Still, this effect becomes negligible once the difference exceeds a certain threshold. Second, when the friction coefficient between the BVA container and the target structure is small, the non-fixed connection type exhibits superior damping performance; as the friction coefficient increases, its performance converges to that of the fixed connection type. Third, the damping performance of the BVA improves significantly as the mass of the ball increases. Fourth, the damping efficiency of the BVA is inversely proportional to the amplitude of seismic acceleration. However, its performance slightly weakens under strong ground motions; it still maintains a stable damping capacity.

The design code specifies the seismic loads for non-structural components (NSC) regardless of their planar locations. Thus, structures with irregular geometry that exhibit torsional behavior may experience greater seismic loads than those specified by the design code. This study assessed the adequacy of the code-specified equivalent static loads using nonlinear dynamic analysis results from structures intentionally designed to be eccentric, and finally proposed a formula that accounts for torsional amplification effects in buildings. The analysis results indicated that the code-specified equivalent static loads were conservative in the lower stories or near the center of mass. On the other hand, the dynamic analysis-based loads exceeded the equivalent static load in the outer perimeter of the mid- and upper stories. Accordingly, a torsional amplification factor equation was proposed, which is a function of the building's eccentricity ratio and the relative distance from the center of mass. The proposed equation applies to the NSC installed in the stories above the midpoint of the total building height. For a building with zero eccentricity or NSC at the center of mass, the function was set to unity.

To improve the seismic performance of a cabinet, a TMD was designed and its dynamic behavior was experimentally investigated as a basic study on vibration reduction. For TMD vibration test, a testing machine base, sliding base and jig were constructed. TMD and base were excited at the same frequency, and their natural frequencies showed a phase difference of approximately 90 degrees. The specifications of the experimental TMD were 20 kg mass, 10% damping ratio, and 7 L of oil. Seismic tests were conducted to investigate the dynamic behavior of the cabinet under earthquakes and the vibration characteristics of the cabinet with and without TMD. Vibration tests were conducted with the cabinet door fully closed, and the acceleration at the top of the cabinet was measured. The maximum acceleration was reduced by approximately 36% when TMD was installed compared to when it was not installed. The experimental results clearly demonstrated the effectiveness of TMD in reducing cabinet vibration.

This study investigates the seismic fragility of nuclear power plant (NPP) auxiliary structures by incorporating material aging deterioration into machine learning–based response prediction models. An artificial neural network (ANN) was developed using 17 seismic and material parameters, achieving high predictive accuracy (R2 = 0.96) while significantly reducing computational demands compared with conventional finite element analyses. By combining the ANN with Monte Carlo simulations, fragility curves for Motor Control Center (MCC) cabinet anchors were derived at resonance frequencies of 10 Hz and 15 Hz. Results indicate that equipment with higher resonance frequency (15 Hz) exhibits lower seismic vulnerability due to reduced sensitivity to dominant low-frequency seismic components. When material deterioration was introduced, fragility curves shifted toward lower ground motion intensities, reflecting increased failure probabilities and approximately 20% reduction in median seismic capacity. These findings highlight the necessity of considering aging effects in probabilistic seismic risk assessments and demonstrate the efficiency of ML-based surrogate models for quantifying long-term safety margins of NPP structures.

새만금 방조제는 세계에서 가장 긴 방조제로서, 해수 유통, 홍수 조절, 농업 및 산업용수 공급 등 다양한 기능을 수행하는 국가 핵심 인프라이다. 방조제 내 교량은 해수와 내호를 연결하는 주요 구조물로, 교각부에 대형 배수갑문이 일체화되어 일반 교량과는 구성이 상이한 복합 구조적 특성을 지닌다. 그러나 2016년에 제정된 ｢지진⋅화산재해대책법｣과 2023년에 개정된 ｢지진가속도계측 설치 및 운영기준｣에 따르면, 방조제는 지진가속도계 의무 설치 대상 시설에서 제외되어 있다. 이에 따라, 국가적으로 중요한 시설임에 도 불구하고 상시적인 지진 모니터링 체계가 구축되어 있지 않은 실정이다. 최근 대규모 지진의 발생 빈도가 증가함에 따라 주요 사회 기반시설의 내진 성능 평가에 대한 요구가 커지고 있다. 특히 방조제 교량은 배수갑문이나 인양기와 같은 대질량 부속 구조물의 존재로 인해 지진 시 큰 관성력이 발생하며, 이에 따라 특정 주요 부재에 손상이 집중될 가능성이 크다. 본 연구에서는 새만금 방조제 내 배수갑문 교량을 대상으로 상세 비선형 시간이력 해석을 수행하였다. 해석 결과를 통해 잠재적 손상 부위를 도출하였으며, 향후 구조물 의 내진 성능 평가와 구조 건전성 모니터링체계 구축을 위한 지진가속도계의 최적 설치 위치를 제안하였다.

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.

The abstract should clearly state the purpose and nature of the investigation while summarizing the key conclusions in English only. It should be a single paragraph consisting of no more than 200 words. This study presents a method to enhance the seismic performance of a stacked stone pagoda by utilizing a Ball Vibration Absorber (BVA). The governing equations of motion for sliding, the primary failure mode of the stacked stone pagoda, were derived, and a numerical model was developed. Through various numerical analyses, the optimal design parameters of the BVA were identified to maximize its seismic control effectiveness for the pagoda. The BVA device can increase the critical seismic acceleration at which the sliding mode occurs in the structure. Moreover, the seismic control performance of the BVA improves with an increase in the mass of the sphere and the coefficient of friction between the layers. Conversely, as the applied seismic acceleration rises, the effectiveness of the BVA in controlling seismic responses diminishes, although a certain level of control effect is maintained. Finally, as long as the sphere of the BVA maintains a specific range of rolling motion, the radius of the sphere or rolling radius does not significantly impacts its seismic control performance.

Current seismic design provisions prohibit the use of a weak panel zone from using special moment frame (SMF) connections due to concerns that large deformations in these zones may lead to brittle connection failures. However, several experimental studies have demonstrated that moment connections with weak panel zones can exhibit adequate ductility and energy dissipation capacity for SMF connections. This study aims to investigate the impact of weak panel zones on the seismic performance of SMFs utilizing welded unreinforced flange-welded web (WUF-W) connections, as outlined in AISC 358-22. The analysis will consider both four-story and twelve-story SMFs. Each frame will be modeled with either strong or weak panel zones. The findings indicate that SMFs with weak panel zones demonstrate greater ductility and collapse strength compared to their counterparts with strong panel zones.

In the present study, to investigate the seismic behavior of a cabinet under earthquakes, three types of mass blocks (top load, center load, and bottom load) were selected as the cabinet's internal structure, and the vibration characteristics according to the load arrangement were studied. The internal structure simulates the device modules installed inside the cabinet. The cabinet's modal characteristics and response spectrum were evaluated under the three types of loads. Six modes, displacement, and acceleration responses for each load were analyzed. The analysis results showed that mode 1 had the lowest frequency, and that the frequency increased by approximately two times as the mode increased. The change in natural frequency according to load placement was confirmed through modal analysis of the cabinet. The cabinet's displacement and acceleration were greatest in the x-axis and lowest in the y-axis. Displacement and acceleration according to the load distribution at the top, center, and bottom were within a certain range, so the vibration characteristics of the internal structure of the cabinet were limitedly affected.

지진 발생 시 지진으로 인한 피해를 최소화하기 위해서는 지진 발생 이전의 재난 대비와 발생 이후의 복구계획 수립이 중요하다. 특 히 효과적인 대응체계 마련을 위해서는 심각한 피해가 예상되는 건축물을 대상으로 지진위험도를 평가하여 건축물의 피해를 예측하 는 과정이 지역사회를 단위로 수행되어야 한다. 본 논문에서는 건축물의 취약도와 지반운동이 결합되어 결정되는 지진위험도를 평 가하기 위해서 공학적으로 정량적으로 판단할 수 있는 지진 붕괴위험도의 개념을 활용하여 지역단위 평가를 수행하였다. 평가 결과, 행정구역 내 건축물의 구조유형 분포는 해당 지역 붕괴위험도 평가에 유의미한 영향을 미침을 확인하였다. 그러나 일부 지역에서는 구조유형만으로 설명할 수 없는 양상을 보였는데, 이는 지반종류에 따른 영향이 지역단위 붕괴위험도 평가에 있어 미치는 영향이 상 대적으로 크다고 판단할 수 있으며, 합리적인 평가결과 도출을 위하여 건축물의 내진성능에 의한 붕괴위험도와 반드시 함께 고려될 필요가 있음을 설명한다.

교량 구조물은 강진 발생 시에 구성요소들간에 복잡한 비선형 거동을 보이기 때문에 내진성능평가를 위해서는 동적 비선형 거동 을 효과적으로 반영할 수 있는 증분동적해석(IDA)방법이 유리하다. 납-고무받침(LRB)과 탄성받침(RB)을 가진 두 가지 예제교량에 대하여 근거리 및 원거리 지진 각각 40개씩을 사용하여 0.01g~5.0g 범위에 지진세기에 대하여 증분동적해석을 수행하여 지진응답을 평가하였다. IDA 방법에 의해 40개의 지진세기와 교각의 변위비 사이의 관계곡선을 구하였다. 이 관계곡선에서 총 40개 지진세기의 교차점에 해당하는 지진응답들의 분포를 히스토그램으로 전환하여 손상상태 한계값의 초과확률을 구하여 지진취약도 평가하였다. 40개 점들의 지진취약도로부터 하나의 중앙값과 대수표준편차 함수로 평가하는 방법을 제시하여 최종적인 지진취약도 함수를 평가 하였다. 지진취약도 해석방법 중에서 가장 대표적으로 많이 사용되는 확률론적 지진요구도 모델(PSDM)을 이용하여 동일한 해석조 건에 대하여 지진취약도를 평가하였고, 이를 IDA방법에 의한 지진취약도 함수와 비교한 결과 유사한 경향을 나타냄을 알 수 있었다.

본 연구는 수소 저장 용기의 지진 취약도 분석 시 요구되는 막대한 계산 자원 문제를 해결하고자, 기하학적 대칭성을 활용한 1/4 대칭 유한요소 모델(Quarter Model)을 개발하고 그 타당성을 검증하였다. 표준화된 AC 156 인공지진을 이용한 비선형 시간 이력 해석을 통해 Full Model과 응답을 비교한 결과, Quarter Model의 해석 시간을 Full Model의 20%를 가지고 해석을 완료하였으 며, 이에 따른 신뢰성 확보를 위해 최상단 변위를 통해 이를 검증하였을 때 0.13%의 미미한 오차를 보이며 변위 시간 이력 양상 역시 동일한 거동을 보이며 효율성 확보라는 연구 목표를 달성했다. 또한, 고유진동수, 강재와 콘크리트 주요부의 최대 응력에서 모두 높은 수준의 일치도를 보여 정량적 신뢰도를 입증하였다. 이를 통해 제안된 모델은 해석 정확도를 유지하면서 계산 비용을 획기적으로 절감 하는 효율적인 방법론임을 확인하였다. 다만 이는 균질 등방성 재료인 강재에 한정된 대칭 모델이며, 그 외의 재료 사용 시 추가적인 연구를 통한 모델 구축이 필요할 것으로 판단된다.

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.

This study investigates the seismic performance of beam-column connections using Thin-Walled Steel Composite (TSC) beams and Prestressed Reinforced Concrete (PSRC) columns. TSC beams are constructed from U-shaped thin steel plates that are filled with concrete, allowing for composite action with slabs through the use of shear connectors. They are widely applied in industrial buildings due to excellent strength, stiffness, and constructability. However, slender web plates are prone to local buckling, which may compromise their performance during seismic events. To mitigate this issue, internal supports have been introduced to enhance web stability and concrete confinement. Cyclic loading tests on three specimens—with and without internal supports—demonstrated that the supports increased moment capacity, improved energy dissipation, and effectively reduced buckling. Even slender sections demonstrated performance comparable to that of compact sections. All specimens reached peak strength at a 2.44% rotation angle, with damage localized near the supports. A practical connection detail was also proposed, taking into account constructability and structural reliability. The results provide valuable guidance for the seismic design of composite systems in large-scale structures.

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.