• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.361-368
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• 2020

The authors developed a new type of steel slit shear wall (SSSW) having the function of structural condition assessment through visually inspecting the out-of-plane deformation of the designed tapered links subjected to lateral deformation. To facilitate its practical application, this paper studies how to design dimensions of the tapered links. Two parameters, the width-to-thickness ratio of the tapered links and steel yield stress, were studied. The performance of structural condition assessment was affected by both parameters with the width-to-thickness ratio being the controlling one. Through both numerical and experimental study, the designed width-to-thickness ratio of tapered links for different levels of structural condition assessment was established considering the effect of different steel grades used. In practice, the dimensions of tapered links can be determined following the design equation provided. Finally, a design procedure for the proposed SSSW system is provided.

• Wind and Structures
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• v.33 no.6
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• pp.423-435
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• 2021

Although existing algorithms can predict wind speed using historical observation data, for engineering feasibility, most use moment methods and probability density functions to estimate fitted parameters. However, extreme wind speed prediction accuracy for long-term return periods is not always dependent on how the optimized frequency distribution curves are obtained; long-term return periods emphasize general distribution effects rather than marginal distributions, which are closely related to potential extreme values. Moreover, there are different wind speed parent sample types; how to theoretically select the proper extreme value distribution is uncertain. The influence of different sampling time intervals has not been evaluated in the fitting process. To overcome these shortcomings, updated steps are introduced, involving parameter sensitivity analysis for different sampling time intervals. The extreme value prediction accuracy of unknown parent samples is also discussed. Probability analysis of mean wind is combined with estimation of the probability plot correlation coefficient and the maximum likelihood method; an iterative estimation algorithm is proposed. With the updated steps and comparison using a Monte Carlo simulation, a fitting policy suitable for different parent distributions is proposed; its feasibility is demonstrated in extreme wind speed evaluations at Longhua and Chuansha meteorological stations in Shanghai, China.

• Wind and Structures
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• v.35 no.2
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• pp.109-120
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• 2022

The force coefficients of rotating plates in the acceleration stage will vary with rotation rate from 0 to stable rotation rate w₀, which are important for quasi-steady theory of plate-like windborne debris to simulate the trajectory. In this paper, a wind tunnel experiment is carried out to study the effects of geometry and the Reynolds number on the variations of mean force coefficients of rotating plates. The rotational lift coefficients are sensitive to both geometry effect and Reynolds number effect, while the rotational drag and moment coefficients are only sensitive to geometry effect. In addition, new empirical formulas for the rotational lift coefficient and moment coefficients are proposed. Its accuracy is verified by comparing the predicted results with existing test data. Based on the experimental data of rotating plates, a new rotational force model for quasi-steady theory, which can be applied to a wider scope, is proposed to calculate the trajectory of plate-like windborne debris. The results show that the new model provides a better match with the tested trajectories than previous quasi-steady theories.

• Wind and Structures
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• v.35 no.5
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• pp.337-351
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• 2022

As central-slotted box decks usually have excellent flutter performance, studies on this type of deck mostly focus on the vortex-induced vibration (VIV) control. Yet with the increasing span lengths, cable-supported bridges may have critical wind speeds of wind-induced static instability lower than that of the flutter. This is especially likely for bridges with a central-slotted box deck. As a result, the overall aerodynamic performance of such a bridge will depend on its wind-induced static stability. Taking a 1400 m-main-span cable-stayed bridge as an example, this study investigates the influence of a series of deck shape parameters on both static and flutter instabilities. Some crucial shape parameters, like the height ratio of wind fairing and the angle of the inner-lower web, show opposite influences on the two kinds of instabilities. The aerodynamic shape optimization conducted for both static and flutter instabilities on the deck based on parameter-sensitivity studies raises the static critical wind speed by about 10%, and the overall critical wind speed by about 8%. Effective VIV countermeasures for this type of bridge deck have also been proposed.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.131-132
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• 2023

본 연구는 중대재해처벌법 시행 이후 1년 8개월이 지난 현재까지 사업장의 안전 문제에 대한 사회적 인식 부족을 확인하였다. 2023년 사업장 위험성 평가 지침 개정에도 불구하고, 안전 문화 인식과 참여율 저조가 주요 원인으로 확인되었다. 이를 해결하기 위한 방안으로, 안전 리더십의 강조와 개개인의 셀프 리더십을 통한 자기효능감 향상 방법을 제시하였다. 사업장의 안전 문화 확산을 위한 캠페인의 중요성 또한 강조하였으며, 이를 기반으로 한 안전 문화 확산 전략의 재정립이 요구된다는 결론을 도출하였다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.187-188
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• 2022

물류센터의 유형별 산업재해 발생형태를 분류하여 대책을 수립함으로써 동종 및 유사 재해를 사전에 재해를 예방코자 한다. 국내물류센터에서 발생된 6년간의 유형별 발생형태를 세부적으로 분석하여 개선책을 수립하여 물류센터에서 발생한 산업재해 분석을 통해서 재해감소 방안을 모색할 수 있었다. 물류센터의 산업재해 분석을 통해서 재해감소 방안을 제시하므로써 물류센터의 재해율 감소에 도움이 될 것으로 기대된다.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.383-397
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• 2024

To improve the vibration control performance and applicability of traditional particle tuned mass damper (PTMD) and realize the significant characteristic of lightweight design, this study proposes a novel particle tuned mass inerter system (PTMIS) by introducing inerter system (IS) to the PTMD. In the study, the motion equation of single degree of freedom (SDOF) structure attached with PTMIS is established first, then the variation law of the system's vibration reduction performance (VRP) is discussed through parameter analysis, and it is compared with the PTMD to analyze its VRP advantages. Finally, its vibration reduction (VR) mechanism from the perspective of core control force and energy analysis is explored, and its cavity relative displacement from the application perspective is analyzed. The results show that the PTMIS can remarkably improve the vibration control effectiveness of the PTMD. The reason is that the inerter can store energy and transfer the energy to the cavity and particles, which further stimulates the interaction between the two parts, thereby improving the nonlinear energy consumption effectiveness. Also, the IS can amplify the damping element's energy dissipation efficiency. In addition, the PTMIS can effectively reduce the working stroke of the PTMD, and through the analysis of the lightweight characteristics of the PTMIS, it is found that its lightweight advantage can reach nearly 100%.

• Journal of Korea Water Resources Association
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• v.39 no.11 s.172
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• pp.915-922
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• 2006

National Emergency Management Agency is planning a flood disaster mitigation system in urban area. This research is about analysis of runoff reduction efficiency of the alloted detention system which is one of flood disaster mitigation systems in urban area. The alloted detention system is composed of small to middle size detention facilities located in up and middle stream of urban basin. To analyze runoff reduction efficiency of alloted detention system, basic runoff analysis in test area has been carried out and runoff characteristics with size and locations of detention facilities has been simulated. The results of simulation are showing that alloted detention system can reduce the discharge of main stream and detention facilities' size and locations are major parameters of runoff reduction efficiency. It is concluded that alloted detention system can be a useful method in urban area's flood disaster mitigation and can secure safety against flood damages in urban areas.

• Journal of the Society of Disaster Information
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• v.18 no.2
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• pp.395-404
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• 2022

Purpose: Small-scale construction sites have insufficient systematic safety management activities, and due to the characteristics of the construction site, the production structure is complex due to external environmental factors, and the risk of construction equipment is very high. We would like to propose a checklist method among practical risk assessment techniques that can derive risk factors for disaster prevention at small construction sites and reduce disasters. Method: Risk factors were derived by analyzing literature research and disaster cases, and detailed work for a checklist of risk assessment suitable for small-scale construction sites was classified based on risk factor items. Result: Hazard factors were divided into 6 major categories, and 29 detailed types of work were classified based on actual work types, and 80 detailed works were classified accordingly. Conclusion: By arranging risk factors suitable for small-scale construction sites according to the classification system, the lack of expertise in the construction site can be supplemented, and risk factors can be derived more easily and disaster reduction can be expected through establishment of safety measures.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.246-249
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• 2007

This paper discusses the standards for disaster prevention and safety management of rail tunnel. The purpose is to establish safety management standards and methods of disaster prevention for each underground traffic spaces, after the full revision of the cause of accidents and its effects, the function and selection of safety equipment, and the efficiency and convenience of maintenance, standards based on prevention and reduction is proposed to reaction to disaster.