• Earthquakes and Structures
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• 제4권5호
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• pp.527-555
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• 2013

This paper proposes probabilistic models for estimating the seismic demands on reinforced concrete (RC) bridges with base isolation. The models consider the shear and deformation demands on the bridge columns and the deformation demand on the isolation devices. An experimental design is used to generate a population of bridges based on the AASHTO LRFD Bridge Design Specifications (AASHTO 2007) and the Caltrans' Seismic Design Criteria (Caltrans 1999). Ground motion records are used for time history analysis of each bridge to develop probabilistic models that are practical and are able to account for the uncertainties and biases in the current, common deterministic model. As application of the developed probabilistic models, a simple method is provided to determine the fragility of bridges. This work facilitates the reliability-based design for this type of bridges and contributes to the transition from limit state design to performance-based design.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.235-246
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• 2014

The automatic seismic trip system (ASTS) continuously monitors PGA (peak ground acceleration) from the seismic wave, and automatically generates a trip signal. This work presents how the system can be designed by using a systems engineering approach under the given regulatory criteria. Overall design stages, from the needs analysis to design verification, have been executed under the defined processes and activities. Moreover, this work contributes two significant design areas for digitalized ASTS. These are firstly, how to categorize the ASTS if the ASTS has a backed up function of the manual reactor trip, and secondly, how to set the requirements using the given design practices either in overseas ASTS design or similar design. In addition, the methodology for determining the setpoint can be applied to the I&C design and development project which needs to justify the error sources correctly. The systematic approach that has been developed and realized in this work can be utilized in designing new I&C (instrument and control system) as well.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.792-799
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• 2023

Non-reactor nuclear facilities are increasing remarkably in Korea combined with advanced technologies such as life and space engineering, and the diversification of the nuclear industry. However, the absence of a basic classification guideline related to the design of non-reactor nuclear facilities has created confusion whenever related projects are carried out. In this paper, related domestic and international technical guidelines are reviewed to present the classification criteria of non-reactor nuclear facilities in Korea. Based on these criteria, the classification of structures, systems and components (SSCs) for safety controls is presented. Using the presented classification criteria, classification of a hot cell facility, a representative non-reactor nuclear facility, was performed. As a result of the classification, the hot cell facility is classified as the hazard category 3, accordingly, the safety class was classified as non-nuclear safety, the seismic category as non-seismic (RW-IIb), and the quality class as manufacturers' standards (S).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.305-312
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• 1999

This study is intended to propose a systematic and practical life cycle cost(LCC) model for the development of the reliability-based seismic safety and cost-effective performance criteria for design and upgrading of long-span PC bridges. The LCC models consist of five cost functions such as initial cost, repair/replacement cost, human losses, road user cost, and indirect losses of regional economy. The proposed model Is successfully expressed in temrs of Park-Ang damage indices and life cycle damage probability obtained from SMART-DRAIN-2DX which is an existing algorithm for nonlinear time history analysis. The proposed LCC model is successfully applied to a viaduct constructed by PSM, in Seoul. Based on the observations, the proposed systematic procedure for the formulation of LCC model may be useful for the development of the reliability-based seismic safety and cost-effective performance criteria for design and upgrading of long-span PC bridges.

• Steel and Composite Structures
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• 제14권2호
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• pp.155-171
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• 2013

This study analytically evaluated the seismic performance of wind-designed diagrid tall steel buildings in regions of moderate/low seismicity and strong winds. To this end, diagrid tall steel buildings with varying wind exposure and slenderness ratio (building height-to-width ratio) conditions were designed to satisfy the wind serviceability criteria specified in the Korean Building Code and the National Building Code of Canada. A series of seismic analyses were then performed for earthquakes having 43- and 2475- year return periods utilizing the design guidelines of tall buildings. The analyses demonstrated the good seismic performance of these wind-designed diagrid tall steel buildings, which arises because significant overstrength of the diagrid system occurs in the wind design procedure. Also, analysis showed that the elastic seismic design process of diagrid tall steel buildings might be accepted based on some wind exposures and slenderness ratios.

• Earthquakes and Structures
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• 제23권3호
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• pp.315-328
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• 2022

Structures designed for wind have an opposite design approach to those designed for earthquakes. These structures are usually reliable if they are constructed in an area where there is almost no or less severe earthquake. However, as seismic activity is unpredictable and it can occur anytime and anywhere, the seismic safety of structures designed for wind must be assessed. Moreover, the design approaches of wind and earthquake systems are opposite where wind design considers higher stiffness but earthquake designs demand a more flexible structure. For this reason, a novel Machine learning framework is proposed that is used to assess and classify the seismic safety of the structures designed for wind load. Moreover, suitable criteria is defined for the design of wind resistance structures considering seismic behavior. Furthermore, the structural behavior as a result of dynamic interaction between superstructure and substructure during seismic events is also studied. The proposed framework achieved an accuracy of more than 90% for classification and prediction as well, when applied to new structures and unknown ground motions.

• 한국지진공학회논문집
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• 제26권5호
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• pp.211-217
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• 2022

New buildings have been designed using different seismic design standards that have been revised. However, the seismic performance of existing buildings is evaluated through the same performance evaluation guidelines. Existing buildings may not satisfy the performance targets suggested in the current guidelines, but there are practical limitations to discriminating the existing buildings with poor seismic performance through a full investigation. In this regard, to classify buildings with poor seismic performance according to the applied standard, this study aimed to evaluate performance-based investigation of the seismic design proposals of buildings with different design standards. The target buildings were set as RC ordinary moment frames for office occupancy. Changes in seismic design criteria by period were analyzed, and the design spectrum changes of reinforced concrete ordinary moment resisting frames were compared to analyze the seismic load acting on the building during design. The seismic design plan was derived through structural analysis of the target model, compared the member force and cross-sectional performance, and a preliminary evaluation of the seismic performance was performed to analyze the performance level through DCR. As a result of the seismic performance analysis through the derived design, the reinforced concrete ordinary moment frame design based on AIK 2000 has an insufficient seismic performance level, so buildings built before 2005 are likely to need seismic reinforcement.

• 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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.194-201
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• 2000

In this study the modified seismic coefficient method for seismic analysis of buried box structures is developed for practical purpose. The loading coefficient in the modified seismic coefficient method is determined from the results of the response displacement analysis. In the developed method adequate velocity response spectrum in accordance with soil condition is also needed to seismic design of buried box structures, In order to investigate applicability of the modified seismic coefficient method various analyses are performed with different parameters such as depth of base rock height and width of box buried depth and value of standard penetration test. Results from the modified seismic coefficient method are compared with those of the response displacement method in terms of the maximum bending moment and the location of it. From the comparison it is shown that the feasibility of the modified seismic coefficient method for seismic analysis of buried box structures.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.250-255
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• 2017

지진 발생시 지반조건에 의하여 지반운동에 영향을 받으며 내진설계시 지반특성을 고려한 부지응답특성 평가를 수행해야한다. 국내 내진설계기준의 설계지진력을 결정하는 부분은 미국내진설계기준(UBC-1997)을 차용하여 사용하고 있다. 국내 지반특성과 다른 미국의 지반특성에 적합하게 만들어진 기준을 그대로 사용하는 경우 과다 또는 과소 설계의 원인이 될 수 있다. 따라서 국내지반특성에 적합한 설계응답스펙트럼의 개선이 중요하다. 그래서 본 연구에서는 국내 도시지역의 158개 지반을 선정하여 미국 서부지역의 지반 특성과 비교하고 부지응답을 수행하였다. 158개의 지반을 내진설계기준에서 제시하는 분류방법을 이용하여 분류하였을 때 $S_B$에 해당하는 지반이 37개, $S_C$은 107개, 지반 $S_D$은 14개로 분류되었다. 각 분류된 지반과 7개의 입력지진파를 토대로 해석을 수행하였으며, 내진설계기준과 비교 분석 결과, 국내 설계응답스펙트럼은 국내의 도시지역의 지반특성에 비하여 단주기 영역의 증폭을 과소평가하고 장주기 영역의 증폭을 과대평가하는 것으로 나타났다. 158개의 해석대상부지 중에서 77%정도를 차지하는 지반 $S_C$, $S_D$의 결과에서 설계응답스펙트럼과 큰 차이가 발생한다는 것은 국내 내진설계기준에 제시되어있는 증폭계수를 국내 지반특성에 적합하도록 재산정 할 필요성이 있다는 것을 보여준다.