Earticle

연구목적: 본 연구에서는 기존 소방 시설에 사용되고 있는 흔들림방지버팀대에 비하여 설치 면적을 효율적으로 감소시키고, 안정성과 내진 성능이 우수한 4방향 흔들림방지버팀대를 개발하였다. 개발된 4방향 흔들림방지버 팀대의 성능 및 신뢰성을 인장 및 압축 시험과 내진 시험을 통하여 검증하였다. 연구방법: KFI 인증 기준에 따라 정적시험으로서 수평 및 수직 배관에 4방향 흔들림방지버팀태을 설치하여 인장 및 압축 시험을 수행하였으며, 정격 하중에 최대 움직임을 측정하였다. 또한 동적시험으로서 물이 채워진 배관에 4방향 흔들림방지버팀태를 설치하고 가속도센서를 통하여 입력 가진파에 대한 시험응답스펙트럼을 측정하였다. 또한 내진 시험 후 배관 및 흔들림방지버팀대의 이탈, 파손 및 국부변형을 관찰하였다. 연구결과: 인장 및 압축 실험을 수행한 결과, 인 장 및 압축 시에 배관의 최대 움직임은 규정 기준 대비 50%~70% 이하로서 4방향 흔들림방지버팀태의 성능이 매우 우수함을 알 수 있었다. 4방향 흔들림방지버팀태의 내진 시험결과 ,시험응답스펙트럼이 요구응답스펙트 럼을 포괄하고 있음을 알 수 있었다. 시험 종료 후에 배관 및 흔들림방지버팀대의 이탈이나 파손 및 국부변형 등 은 발생하지 않았으며, 시설물의 구조적 안정성이 유지됨을 확인할 수 있었다. 결론: 본 연구에서는 정적 실험 및 동적 실험을 통하여, 개발된 4방향 흔들림방지버팀대가 KFI 인중 기준을 만족하고 있음을 알 수 있었고, 기존 흔들림방지버팀대에 비하여 효율성과 경제성 및 안정성과 내진 성능이 우수함을 확인할 수 있었다.

Purpose: In this study, we developed a 4-way sway prevention brace that efficiently reduces the installation area and has excellent stability and seismic performance compared to the conventionl sway prevention brace used in existing firefighting facilities. The performance and reliability of the developed 4-way way prevention brace were analyzed by the tensile, compression tests and seismic tests. Method: As the static test, 4-way sway prevention braces were installed on the horizontal and vertical pipes to perform the tensile and compression tests based on the KFI certification standard and the maximum movement was measured at the rated load. As a dynamic test, 4-way sway prevention braces were installed in the pipes filled with water, and the test response spectrum to the input excitation wave were measured through the acceleration sensors. After the seismic tests, separation, failure, and local deformation of the pipes, and 4-way sway prevention braces were not observed. Result: The results of the tensile and compression tests indicated that the maximum movement of the pipe during tension and compression was 50% to 70% or less compared to the certification values, indicating that the performances of the 4-way sway prevention braces were very excellent. The results of the the seismic tests indicated that the test response spectrum of the 4-way sway prevention braces is within the required response spectrum. Conclusion: In this study, it was found that the 4-way sway prevention braces satisfied the KFI certification standard and were superior compared to the existing sway prevention brace in terms of the stability, cost, and installation area.

This study developed an automated seismic acceleration sensor test equipment to improve the high measurement uncertainty of existing test equipment with the tilting method. The equipment was developed by setting the legal standards for seismic acceleration sensor test equipment and the problems of existing test equipment as performance indicators. The problems with the existing test equipment, which was manually operated, included measurement error owing to handling vibration, occurrence of angle error according to the observation field, and measurement method without considering hysteresis. The developed equipment satisfied the legal standards, and the problem of measurement error owing to handling vibration and angle error according to the observation field of view was improved by attaching a servo motor and precision level to the measurement equipment. Hysteresis control has been improved by adding the delay time control function of dedicated software (S/W). The developed automated seismic acceleration sensor test equipment can be used for the testing of seismic acceleration sensors, and the operating software reduced measurement uncertainty in the testing of seismic acceleration sensors.

시간경과 탄성파 모니터링 기법의 국내 활용 가능성을 확인하기 위하여, 슬라이프너 CCS 프로젝트의 탐사자료에 적용하고 분석하였다. 입력에 활용한 탄성파 4D 자료는 1994년 취득된 기준 자료와 2008년 취득된 모니터링 자료로 구성된다. 기준 자료와 모니터링 자료의 차이를 계산한 결과 지하에 주입된 이산화탄소의 부존 영역이 탄성파 진폭 변화로 뚜렷하게 확인되었다. 4D 처리 모듈 중시간 변화 진폭 회수와 평활화 모듈의 입력 매개변수를 시험하고 진폭 변화에 미치는 결과를 확인하였다. 진폭 회수는 전체 트레이스에 대하여 적용하여 진폭 변화의 가시성을 높일 수 있으며, 평활화 모듈은 신호 대 잡음 비를 향상시켰다. 도출된 진폭 변화를 슬라이프너 프로젝트에서 발표된 결과와 비교하여, 이산화탄소 부존 영역이 일치함을 확인하였다. 슬라이프너 CCS프로젝트의 탐사 자료처리 방법론 시험 경험은 향후 국내 이산화탄소 지중저장 연구 및 실증화 성공을 위한 탄성파 4D 모니터링 기술 정립의 기틀이 될 것으로 기대된다.

To verify the potential of time-lapse seismic monitoring for the Korean domestic CCS project, we analyzed the Sleipner project dataset. Time-lapse data used for input consists of the baseline and monitoring data that were recorded in 1994 and 2008, respectively. The difference between the baseline and the monitoring data, subsurface CO2 plume, was clearly identified as a change in the seismic amplitude. To investigate the effect of time-lapse processing, we tested input parameters of time-varying amplitude gain and lateral smoothing modules. The result shows that gain should be applied on the entire traces, and smoothing can increase the signal to noise ratio. By comparing the derived amplitude difference with the results of the previous paper in the Sleipner project, it was confirmed that the CO2 plume region was consistent. The accumulated experience of the Sleipner data will be embodied in a best framework to assist future CO2 storage project in Korea.

국내외적으로 지진의 발생이 빈번함에 따라 인명 및 재산 피해가 발생하고 추가적인 경제적 손실을 초래한다. 국내의 비내진으로 설계된 구조물의 보수 보강이 시급할 뿐만 아니라 지진에 대한 관심이 고조됨에 따라 내진보강에 대한 연구가 활발히 진행되고 있다. 최근 고연성 보강재를 사용한 내진보강기법이 소개되면서 강성보강보다는 연성보강에 대한 신뢰도가 높아지고 있다. 따라서 본 연구에서는 연성보강 재료로써 최근 각광받고 있는 폴리우레아를 이용한 내진보강공법을 소개하기 위해서, 폴리우레아로 보강한 RC 시편에 대하여 일축압축시험과 유사동적실험을 수행하였다. 일축압축시험에서 폴리우레아 보강시 강도가 증진되었을 뿐 아니라 연성거동을 확인할 수 있었으며, 실제 지진파를 적용한 유사동적실험에서는 상대변위, 주철근의 변형률, 변위연성도, 소산에너지 모두 향상된 보강성능을 확인할 수 있었다. 연성보강의 목적으로 개발한 폴리우레아 보강방법은 기둥부재의 내진보강에 유용하게 사용될 것이라고 판단된다.

As earthquakes have frequently happened all over the world, huge losses of human life and property have occurred. Therefore, retrofitting and strengthen technologies of non-seismically designed structures in Korea are urgent. Also, there has been a growing interest about seismic retrofitting, where researches on the topic have been actively pursued in Korea. The study results showed that ductility inducing retrofitting method is more superior stiffness inducing method. In Japan, Super Reinforcement with Flexibility (SRF) was introduced. Therefore, in this study, seismic performance evaluation was performed through pseudo dynamic test and uniaxial compression test for RC column retrofitted by PolyUrea for ductility inducing retrofitting material. Uniaxial compression test results showed that strength of all specimens retrofitted by PolyUrea was higher than that of RC specimens. Also, all specimens retrofitted by PolyUrea also showed ductile fracture behavior. In pseudo dynamic test, by appling real earthquake record, the seismic behavior of RC column reinforced by PolyUrea was evaluated through relative displacement, reinforcement strain, displacement ductility, and dissipation energy. The results showed that PolyUrea helped to enhance seismic performance of RC columns.

Embankment of agricultural reservoir started by four major rivers project. Most agricultural reservoirs must insure the agricultural water, they need must be ensured stability of embankment. Recently, there is a growing interest in seismic stability of structure by earthquake. Results of evaluation of the structural stability through seismic vibration test and numerical analysis, maximum displacement and the maximum acceleration is a similar trends. Appeared by increasing occurrence of the value of the displacement and acceleration of the structure with the result long period wave type in accordance with the seismic wave in the case of seismic waves, which shows the results of similar tendency as long period wave type consists of waveform seismic acceleration. Model test and numerical analysis results with in order to increase embankment agricultural reservoir, the displacement was found to ensure it is displayed within one percentage structural stability of the embankment.

Some ceiling systems were damaged by Pohang earthquake so concerns on the seismic performance of them has raised. In this study the shake table test of the ceiling system was conducted to investigate the dynamic behavior and those failure type under earthquake condition. The test specimen was a gypsum panel ceiling system with M-bar type which was used in school building. As the result of the test, minor damage such as falling of single panel around the perimeter and separation from molding was found under domestic design earthquake level. The acceleration response of the ceiling system was amplified over the input acceleration but below 2.5 times. Therefore, it seemed that it was reasonable to use a response amplification factor of 2.5 as the seismic design parameter. Its displacement response was increased as the boundary condition of perimeter was changed by increasing input acceleration. Additionally, the simple spring-mass model of the ceiling system using the lumped mass of the system supported by a hanger and flexure stiffness of the hanger was suggested, and the boundary condition between the panels and the molding part of the ceiling system was assumed as the axial springs. The seismic response analysis was performed to verify the model and to evaluate the seismic demand by the three types of the hanger length. The analysis model could predict properly the displacement response of the specimen when the stiffness of the axial spring was applied to be low. Moreover, analysis results showed that the seismic force and displacement demands affected by the length of the hanger and boundary rigidity, so it needed to be considered for the seismic design of the ceiling system.

본 논문에서는 실제 크기의 세가지 철근 콘크리트 골조 실험체를 4.0 × 4.0 m 평면, 적재하중 300kN의 진동대에 올려 동적 성능 평가를 수행하였다. 두가지 내진보강 시스템을 평가하기 위해 실험체들이 El Centro NS성분 지진파로 실험이 수행되었다. (1) 강봉으로 보강된 실험체; (2) 원형개구부가 있는 강판 전단벽 보강 실험체. 실험결과 비내진 상세로 설계된 기본 실험체는 El Centro 지진파 160% 가진 시 과도한 균열로 인해 실험이 중지되었다. 강봉으로 보강된 내진보강 실험체는 220% 가진 시 강봉의 파단으로 인해 실험이 종료되었다. 반면, 원형개구부가 있는 강판 전단벽 보강 실험체는 300%까지 가진되었다. 실험결과를 통해 두 보강 시스템의 보강효과, 변형 능력과 에너지 소산 능력이 기본 실험체와 비교 평가되었다.

This paper presents dynamic performances obtained from three full-scale reinforced concrete (RC) frames tested on shaking table which is 4.0 × 4.0 m in plane and with a payload capacity of about 300kN. The frames were subjected to the El Centro NS input ground motion and relevant to two seismic-resistance systems: (1) use of a X-bracing reinforcement; (2) infilled steel plate with circular opening installed in the boundary concrete elements. The test of a reference specimen with non-seismic design was stopped due to excessive cracks when subjected to 160% acceleration of El Centro earthquake. Shaking test on specimen with X-bracing was terminated during 220% acceleration because of the fracture in steel rod. On the other hands, a frame strengthened by infilled steel shear wall with circular opening was subjected up to 300% acceleration. The strengthening effect, deformation capacity and energy dissipation effect are evaluated for two strengthening systems compared to reference frame.

Large spatial structures can not predict the dynamic behavior due to the lack of construction and design practices. The spatial structure are generally analyzed through the numerical simulation and experimental test in order to investigate the seismic response of large spatial structures. In the case of analysis for seismic response of large spatial structure, the many studies by the numerical analysis was carried out. However, researches by the shaking table test are very rare. In this study, a shaking table test of a small-scale arch structure was conducted and the dynamic characteristics of arch structure are analyzed. And the seismic response of arch structures are investigated according to the various column cross-section and length. It is found that the horizontal seismic responses are hardly affected by the column rigidity in the tests result of the small-scale arch structure. But, vertical seismic response has been heavily influenced by the column rigidity. And, arch structures with relatively large rigidity column were significantly greater seismic response. This is because the seismic response of the roof structure are affected by the column rigidity of the spatial structure.

This research is to develop more effective seismic isolation system and to standardize a design processor for a seismic isolation structure system based on energy method by applying a isolation damper using HTS(High Toughness Steel which has been being studied) to the seismic isolation system. This research is conducted in four different stages. First, design two types of specimen for a shaking table test. One is not applied a seismic isolation system, the other is applied a seismic isolation system. Second, expect the dynamic characteristics of each specimen through analytical study using computer program Midas Gen ver.741. Third, compare analytical result with experimental result which will be obtained from a shaking table test next time. Lastly, suggest a design processor for a seismic isolation structure system based on energy method. In this study, our efforts especially focused on the first and second stage.

Many piloti-type RC buildings were damaged by Pohang earthquake. It is necessary to reflect the characteristics of domestic buildings and failure mode by an earthquake to the post-earthquake safety evaluation criteria. In this study, the behavior characteristics and failure mode of RC walls of piloti-type buildings subjected to eccentric axial load was investigated by the reversal cyclic test. The variables were the aspect ratio(height to length) of the wall and the eccentricity which was different because the axial force was applied at the same position from the center of the wall specimens. As a result of the experiment, the slender wall was dominated by the flexure behavior. On the other hand, flexure-shear cracks occurred predominantly in the wall with a small aspect ratio. The crack patterns in the positive and negative loading directions were different due to the influence of eccentricity. The number of crack increased, and the rotation of the wall increased while the maximum horizontal strength decreased when the shear moment and the eccentric moment acted in the same direction by the eccentric axial force.

This study examines the seismic behavior of a horizontal layout graphite core model for gas-cooled microreactors, with a focus on the impact of preload variations on structural dynamics and safety. A 1:1 scale partial planar model replicating the discrete graphite brick assembly was designed to respond to in-plane seismic responses. Experimental methods integrated contact-based accelerometers and non-contact digital image correlation to capture multi-point displacement and acceleration data. Three preload levels (15 kN, 10 kN, 5 kN) were applied via lateral metal restraints to evaluate their effects on stiffness, damping, and frequency characteristics. Sine-sweep tests demonstrated that lower preloads increased damping ratios (up to 27 %) and natural frequencies (5 Hz at 5 kN vs. 4 Hz at 15 kN), attributed to lateral contact with side restraints and internal friction among loosened bricks. Furthermore, finite element analysis demonstrates that larger gaps lead to lower structural frequencies, thereby confirming that structural stiffness is correlated with lateral support. Seismic tests using 0.3g zero-period acceleration inputs validated structural integrity: control rod channel displacements remained within a 1 cm radius, ensuring safe shutdown capability. This work highlights the non-linear relationship between preload, lateral constraints, and dynamic behavior, with higher preloads reducing stiffness by increasing gaps. The results advance safety assessments for microreactors and offer practical insights for mitigating risks in next-generation nuclear systems.

In this study, crosshole seismic test, donwhole seismic test, SPT uphole test, and suspension PS logging (SPS logging) were conducted and the shear wave velocities of these tests were compared. The test demonstrated the following result: Downhole tests showed similar results compared to those of crosshole tests, which is known to be relatively accurate. SPS logging showed reliable results in the case of no casing, i.e. in the rock mass, while, in the case of soil ground, its values were lower or higher than those of other tests. SPT-uphole tests showed similar results in the soil ground and upper area of rock mass compared to other methods. However, reliable results could not be obtained from these tests because SPT sampler could not penetrate into the rock mass for the tests.

In view of the prefabricated shear wall structure, this paper puts forward a prefabricated integrated shear wall structure inwhich the concrete filled wall with hydrophobic rock wool board partition is poured, produced and installed together with thesolid wall limb. Based on the quasi-static test of four concrete double-leg shear walls with the same size, wall limb andreinforcement of coupling beam, the seismic performance of shear walls without filled and integrated whole filled is explored,and the characteristics of failure form, bearing and deformation capacity, stiffness, ductility and energy dissipation capacityof the walls are summarized. The experimental results show that the flexural shear failure occurs in the prefabricatedintegrated shear wall under horizontal reciprocating load. Compared with the unfilled wall component, the lateral stiffness andshear bearing capacity are obviously improved, and the seismic performance is better at the same time. Based on the ABAQUSanalysis software, the quasi-static test results are analyzed by numerical simulation and the hysteresis curve with goodagreement is obtained. According to the test results and the numerical simulation, a reasonable filled wall structure schemefor precast integrated concrete shear wall structure is put forward.

This paper is a study on a nuclear water chiller. It presents a test-verified finite element model of a water chiller to be used at a Nuclear Power Plant. The test-verified model predicts natural frequencies within 5% for all major modes below 50 Hz. This model accurately represents the dynamic characteristics of the actual hardware and is qualified for its use in the final stress analysis for seismic verification.

To quantify the conservatism of existing ASME strain-based evaluation methods for seismic loading, this paper presents very low cycle fatigue test data of elbows under various cyclic loading conditions and comparison of evaluation results with experimental failure cycles. For strain-based evaluation methods, the method presented in ASME BPVC CC N-900 and Sec. VIII are used. Predicted failure cycles are compared with experimental failure cycle to quantify the conservatism of evaluation methods. All methods give very conservative failure cycles. The CC N-900 method is the most conservative and prediction results are only ~0.5% of experimental data. For Sec. VIII method, the use of the option using code tensile properties gives ~3% of experimental data, and the use of the material-specific reduction of area can reduce conservatism but still gives ~15% of experimental data.

Recently, studies have been actively conducted on seismic design and improvement of the seismic performance of bridges, buildings, factories, and plants. In particular, heavy items that are being manufactured or waiting to be shipped from factories (such as generators, engines, and boilers) must be equipped with seismic stoppers to prevent them from moving or falling during an earthquake. Seismic stoppers should be suitably determined by the size and weight of these heavy items; however, they have no general design standard. In this study, structural analyses and seismic tests were conducted to evaluate the performance of newly designed seismic stoppers. Structural analysis was performed on three stopper models to estimate the external load at which the yield stress of the material was not exceeded. Based on the analysis results, a seismic test of the stopper was carried out in accordance with the AC156 test method. Finally, product specifications for all three seismic stopper models were determined and their static/dynamic load performance was evaluated.

Pseudo dynamic test for seven circular RC bridge piers has been carried out to investigate their seismic performance subjected to expected artificial earthquake motions. The objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete bridge piers, which have been widely used for railway and urban transportation facilities. Important test parameters are confinement steel ratio, and input ground motion. The seismic behavior of circular RC bridge piers under artificial ground motions has been evaluated through displacement ductility, cumulative energy input, and dissipation capacity. It can be concluded that RC bridge piers designed in a limited ductile behavior provision of Eurocode 8 have been determined to show good seismic performance even under moderate artificial earthquakes.

Damage to nuclear power plants causes human casualties and environmental disasters. There are electrical facilities that control safety-related devices in nuclear power plants, and seismic performance is required for them. The 2016 Gyeongju earthquake had many high-frequency components. Therefore, there is a high possibility that an earthquake involving many high frequency components will occur in South Korea. As such, it is necessary to examine the safety of nuclear power plants against an earthquake with many high-frequency components. In this study, the shaking table test of electrical facilities was conducted against the design earthquake for nuclear power plants with a large low-frequency components and an earthquake with a large high-frequency components. The response characteristics of the earthquake with a large high-frequency components were identified by deriving the amplification factors of the response through the shaking table test. In addition, safety of electrical facility against the two aforementioned types of earthquakes with different seismic characteristics was confirmed through limit-state seismic tests. The electrical facility that was performed to the shaking table test in this study was a motor control center (MCC).