• 대한안전경영과학회지
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• 제25권2호
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• pp.187-192
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• 2023

In piping systems, trapeze hangers are subjected to vertical and horizontal seismic loads and stiffeners are used. In this study, monotonic compression tests were conducted with the removable stiffeners using three variables: stiffener clamp fixing position, section length, and installation direction. The maximum load reinforced with stiffeners could withstand a compressive load of 11kN by applying a safety factor of 10%. It could be estimated that the fixing clamp spacing or the length of shape and load had a proportional relationship. And the stiffener must be fixed in the direction of the strong axis on hinge parts. Also the stiffener buckiling load design proposes to use a method of calculate the flexural buckling compressive strength of and unreinforced full threaded bolt.

• 한국안전학회지
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• 제33권1호
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• pp.81-87
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• 2018

The seismic response, the natural frequencies and the mode shapes of an offshore wind turbine with twisted tripod substructure subject to various pile-ground interactions are discussed in this paper. The acceleration responses of the tower head by four historical earthquakes are presented as the seismic response, while the other loads are assumed as ambient loads. For the pile-ground interactions, the fixed, linear and nonlinear models are employed to simulate the interactions and the p-y, t-z and Q-z curves are utilized for the linear and nonlinear models. The curves are designed for stiff, medium and soft clays, and thus, the seven types of the pile-ground interactions are used to compare the seismic response, the acceleration of the tower head. The mode shapes are similar to each other for all types of pile-ground interactions. The natural frequencies, however, are almost same for the three clay types of the linear model, while the natural frequency of the fixed support model is quite different from that of the linear interaction model. The wind turbine with the fixed support model has the biggest magnitude of acceleration. In addition, the nonlinear model is more sensitive to the stiffness of clay than the linear pile-ground interaction model.

• Structural Engineering and Mechanics
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• 제41권1호
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• pp.1-24
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• 2012

A reinforced concrete (RC) framed structure detailed according to non-seismic detailing provisions as per Indian Standard was tested on shake table under dynamic loads. The structure had 3 main storeys and an additional storey to simulate the footing to plinth level. In plan the structure was symmetric with 2 bays in each direction. In order to optimize the information obtained from the tests, tests were planned in three different stages. In the first stage, tests were done with masonry infill panels in one direction to obtain information on the stiffness increase due to addition of infill panels. In second stage, the infills were removed and tests were conducted on the structure without and with tuned liquid dampers (TLD) on the roof of the structure to investigate the effect of TLD on seismic response of the structure. In the third stage, tests were conducted on bare frame structure under biaxial time histories with gradually increasing peak ground acceleration (PGA) till failure. The simulated earthquakes represented low, moderate and severe seismic ground motions. The effects of masonry infill panels on dynamic characteristics of the structure, effectiveness of TLD in reducing the seismic response of structure and the failure patterns of non-seismically detailed structures, are clearly brought out. Details of design and similitude are also discussed.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1345-1356
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• 2021

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).

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.161-170
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• 2020

본 연구에서는 공공 시설물을 대상으로 설치된 지진가속도 계측 시스템의 운영 효율성 개선을 위하여 지진 이벤트 신호 변환 및 처리 알고리즘을 개발하였다. 더불어 처리된 지진 가속도 시간이력의 분석을 통해 건축물의 안전성을 평가할 수 있는 평가 방법과 평가 기준을 제안하였으며, 테스트베드 건축물에 적용하여 그 작동과 활용성을 검증하였다. 이를 통해 지진 이벤트 계측자료의 분석 정확성을 확보하고, 지진재해 상황에서 재난 대응의 방향과 우선순위 판단을 위한 의사결정 지원자료로 활용할 수 있을 것으로 판단된다.

• 한국공간구조학회지
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• 제20권1호
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• pp.12-17
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• 2020

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.190-202
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• 2018

Maintaining the integrity of the major equipment in nuclear power plants is critical to the safety of the structures. In particular, the soundness of the piping is a critical matter that is directly linked to the safety of nuclear power plants. Currently, the limit state of the piping design standard is plastic collapse, and the actual pipe failure is leakage due to a penetration crack. Actual pipe failure, however, cannot be applied to the analysis of seismic fragility because it is difficult to quantify. This paper proposes methods of measuring the failure strain and deformation angle, which are necessary for evaluating the quantitative failure criteria of the steel pipe elbow using an image measurement system. Furthermore, the failure strain and deformation angle, which cannot be measured using the conventional sensors, were efficiently measured using the proposed methods.

• 한국지진공학회논문집
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• 제13권4호
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• pp.57-65
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• 2009

본 연구에서는 HAZUS와 같은 지진위험도 추정을 위한 입력으로서 교량구조물에 대한 대표 지진취약도 함수를 도출하기 위하여 기존에 수행되었던 안전율 평가 결과를 이용하여 일련의 교량군에 대한 대표 지진취약도 함수를 도출하는 방법을 제안하였다. 지진응답해석 결과를 근거로 하여 제시된 교량 집단의 각 부재별 안전율을 정리하였으며 이 안전율 결과를 이용하여 각 파괴모드별 지진취약도 곡선을 도출하였다. 각 부재별로 평가된 지진취약도 함수를 이용하여 HAZUS의 입력으로 사용할 수 있는 손상단계별 지진취약도 함수를 도출하였다. 부재별 파괴모드를 이용하여 교량전체의 시스템 취약도를 도출하기 위하여 고장수목을 사용하였다. 결과적으로 본 연구에서는 기존의 안전율결과를 이용하여 취약도결과를 도출할 수 있는 방법을 제시하였다.

• Structural Engineering and Mechanics
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• 제43권4호
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• pp.545-560
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• 2012

Design codes provide the minimum requirements for the design of code-compliant structures to ensure the safety of the life and property. As for code-exceeding buildings, the requirements for design are not sufficient and the approval of such structures is vague. In mainland China in recent years, a large number of code-exceeding tall buildings, whether their heights exceed the limit for the respective structure type or the extent of irregularity is violated, have been constructed. Performance-based seismic design (PBSD) approach has been highly recommended and become necessary to demonstrate the performance of code-exceeding tall buildings at least equivalent to code intent of safety. This paper proposes the general methodologies of performance-based seismic analysis and design of code-exceeding tall buildings in Mainland China. The PBSD approach proposed here includes selection of performance objectives, determination of design philosophy, establishment of design criteria for structural components and systems consistent with the desirable and transparent performance objectives, and seismic performance analysis and evaluation through extensive numerical analysis or further experimental study if necessary. The seismic analysis and design of 101-story Shanghai World Financial Center Tower is introduced as a typical engineering example where the PBSD approach is followed. The example demonstrates that the PBSD approach is an appropriate way to control efficiently the seismic damage on the structure and ensure the predictable and safe performance.

• Earthquakes and Structures
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• 제11권6호
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• pp.1143-1164
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• 2016

Time Delay of Arrival (TDOA) estimation methods based on correlation function analysis play an important role in the micro-seismic event monitoring. It makes full use of the similarity in the recorded signals that are from the same source. However, those methods are subjected to the noise effect, particularly when the global similarity of the signals is low. This paper proposes a new approach for micro-seismic monitoring based on cross wavelet transform. The cross wavelet transform is utilized to analyse the measured signals under micro-seismic events, and the cross wavelet power spectrum is used to measure the similarity of two signals in a multi-scale dimension and subsequently identify TDOA. The offset time instant associated with the maximum cross wavelet transform spectrum power is identified as TDOA, and then the location of micro-seismic event can be identified. Individual and statistical identification tests are performed with measurement data from an in-field mine. Experimental studies demonstrate that the proposed approach significantly improves the robustness and accuracy of micro-seismic source locating in mines compared to several existing methods, such as the cross-correlation, multi-correlation, STA/LTA and Kurtosis methods.