• Steel and Composite Structures
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• v.34 no.5
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• pp.625-641
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• 2020

The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA ≈ 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

• Journal of Distribution Science
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• v.14 no.4
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• pp.55-66
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• 2016

Purpose - This article aims to explore the characteristics of disaster risk distribution information in China. Also, this research attempts to analyze the findings of risk communication using case study in chronological order in terms of social amplification of risk. To achieve the purpose, the paper reviews the trends and issues of risk communication in China, with an emphasis on examining earthquakes by a chronological approach. In these regards, we hope that some relevant findings from this empirical study with cases will be able to enhance national risk communication and provide implications in Korea as well. Research design, data, and methodology - The conceptual framework of this study is theoretically based on the risk amplification model, which describes signals about risk transmitted and processed by individuals and social groups. The social amplification of risk also reflects the interactions of social groups about disaster-related risk issues, which are potential amplifiers or attenuators of communication signals. The key concept of social amplification implies that the risks pertaining to natural disasters interact with social, psychological, institutional, and cultural processes in ways that can affect public perceptions of risk. SMCRE Model is methodologically employed to examine risk communication history of China with the focus on natural disaster. Four earthquakes are selected to figure out the chronological characteristics of risk communication since 1970s. He bei Tang Shan earthquake is selected as an example disaster before 1990's, while the earthquake in Yun Nan Jiang is explored for the case study of 1990's. The earthquake in Si Chuan Wen Chuan is also examined as a example disaster of 2000's. The recent earthquake in Si Chuan Ya An Lu Shan is selected as a case of 2010s. Results - SMCRE model in this case study is operationally defined as a methodology and applied to the four earthquakes occurred in China. SMCRE model describes the exchange of risk information and is also applied to all forms of communication between stake holders. Each factor of risk communication includes source, message, channel, receiver and effect. It is notable that a big progress has been made on disaster risk communication in China for the past 40 years. We also found that highly developed information technology has enabled Chinese society to better cope with natural disaster, leading to enhanced disaster risk communication. It is mainly found from case study that the disaster risk communication of China has been involved with political situation, which derived from the change of government for the past 40 years. Conclusion - From this historical research, it can be inferred that the policies and politics of Chinese leaders have had a more critical role to play in the process of source of risk communication than those of any other countries. The results of this paper also support that the effective risk communication involves not only the improved reliability of local government as a key factor of disaster risk communication, but also is accompanied by international cooperation for substantial collaboration with stake holders.

• Geomechanics and Engineering
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• v.32 no.4
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• pp.375-385
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• 2023

There are many joint fissures distributed in the engineering rock mass. In the process of geological history, the underground rock mass undergoes strong geological processes, and undergoes complex geological processes such as fracture breeding, expansion, recementation, and re-expansion. In this paper, the damage-stick-slip process (DSSP), an analysis model used for rock mass failure slip, was established to examine the master control and time-dependent mechanical properties of the new and primary fractures of a multi-fractured rock mass under the action of stress loading. The experimental system for the recemented multi-fractured rock mass was developed to validate the above theory. First, a rock mass failure test was conducted. Then, the failure stress state was kept constant, and the fractured rock mass was grouted and cemented. A secondary loading was applied until the grouted mass reached the intended strength to investigate the bearing capacity of the recemented multi-fractured rock mass, and an acoustic emission (AE) system was used to monitor AE events and the update of damage energy. The results show that the initial fracture angle and direction had a significant effect on the re-failure process of the cement rock mass; Compared with the monitoring results of the acoustic emission (AE) measurements, the master control surface, key blocks and other control factors in the multi-fractured rock mass were obtained; The triangular shaped block in rock mass plays an important role in the stress and displacement change of multi-fracture rock mass and the long fissure and the fractures with close fracture tip are easier to activate, and the position where the longer fractures intersect with the smaller fractures is easier to generate new fractures. The results are of great significance to a multi-block structure, which affects the safety of underground coal mining.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.131-136
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• 2013

Automobile was first introduced in 1903 in South Korea, the masses of the car was carried out rapidly compared to other countries. However, many people were killed in a traffic accidents and economic loss was occurred due to the spread of the automobile. In South Korea, 2012, traffic accident occurred 223,656 times, 5,392 fatality, 344,565 injured people. In the last five years, about 224,000 accidents per year were occurring. In other words, 610 traffic accidents occur and about 15 people pass away in one day. In addition, the proportion of traffic accidents is first place in the OECD countries and it is very high in the world. Understand occurrence tendency of traffic accident, accident frequency rate of the driver who drives more than 10 years was higher than the novice driver. In addition, as a result of examining the cause of the traffic accident, breach of safe driving obligation appears highest case (125,391 times), and followed by signal violation, break safety distance. Therefore, the majority of traffic accidents occurred by the lack of safety awareness of the driver. In this study, prevent the loss of human life and property in traffic disaster, by establish disaster prevention measures that investigated by questionnaire survey and statistical data of the state of consciousness and driving posture in response to the driving history of the driver.

• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.65-73
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• 2015

Detailed finite element (FE) analyses of a full-scale four-story steel frame structure, subjected to consecutive 60% and 100% excitations from the JR Takatori records during the 1995 Hyogoken-Nanbu earthquake, are conducted using E-Simulator. The four-story frame was tested at the largest shake-table facility in the world, E-Defense, in 2007. E-Simulator is a parallel FE analysis software package developed to accurately simulate structural behavior up to collapse by using a fine mesh of solid elements. To reduce computational time in consecutive dynamic time history analyses, static analysis with gravity force is introduced to terminate the vibration of the structure during the analysis of 60% excitation. An overall sway mechanism when subjected to 60% excitation and a story mechanism resulting from local buckling of the first-story columns when subjected to 100% excitation are simulated by using E-Simulator. The story drift response to the consecutive 60% and 100% excitations is slightly smaller than that for the single 100% excitation.

• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.179-196
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• 2013

An experimentally measured single footfall trace (SFT) from a walking subject needs to be extended into a continuous force curve, which can then be used as load for floor vibration serviceability assessment, or on which further analysis like discrete Fourier transform can be conducted. This paper investigates the accuracy, applicability and parametrical sensitivity of four extension methods, Methods I to IV, which extends the SFT into a continuous time history by the walking step rate, stride time, double support proportion and the double support time, respectively. Performance of the four methods was assessed by comparing their results with the experimentally obtained reference footfall traces in the time and frequency domain, and by comparing the vibrational response of a concrete slab subjected to the extended traces to that of reference traces. The effect of the extension parameter on each method was also explored through parametrical analysis. This study finds that, in general, Method I and II perform better than Method III and IV, and all of the four methods are sensitive to their extension parameter. When reliable information of walking rate or gait period is available in the test, Methods I or II is a better choice. Otherwise, Method III, with the suggested extension parameter of double support time proportion, is recommended.

• Steel and Composite Structures
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• v.41 no.5
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• pp.713-730
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• 2021

The seismic performance of rigid steel frames is widely investigated, but that of semi-rigid (SR) steel frames are not studied extensively, especially for near-field earthquakes. In this paper, the performances of five and ten-story steel SR frames having different degrees of semi-rigidity are evaluated at four performance points in the four different deformation states, namely, the elastic, elasto-plastic, plastic, and near collapse states. The performances of the SR frames are measured by the response parameters including the maximum values of the top floor displacement, base shear, inter-story drift ratio, number of plastic hinges, and SRSS of plastic hinge rotations. These response parameters are obtained by the capacity spectrum method (CSM) using pushover analysis. The validity of the response parameters determined by the CSM is evaluated by the results of the nonlinear time history analysis (NLTHA) for both near and far-field earthquakes at different PGA levels, which are consistent with the performance points. Results of the study show that the plastic hinges of SR frame significantly increase in the range of plastic to near-collapse states for both near and far-field earthquakes. The effect of the degree of semi-rigidity is pronounced only at higher degrees of semi-rigidity. The predictions of the CSM are fairly well in comparison to the NLTHA.

• Advances in concrete construction
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• v.7 no.3
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• pp.183-189
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• 2019

In this study, it has been tried to prepare an analytical fragility curves for isolated straight continues highway bridges by considering different spectral intensity measures. A three-span concrete isolated bridge has been selected and the seismic performance of the bridge has been improved by Lead Rubber Bearing (LRB). Incremental Dynamic Analysis (IDA) is applied to the bridge in longitudinal direction. A suite of 14 earthquake ground motions from medium to sever motions are scaled and used for nonlinear time history analysis. Fragility function considers the relationship of earthquake intensity measures (IM) and probability of exceeding certain Damage State (DS). A full three dimensional finite element model of the isolated bridge has been developed and analyzed. A wide range of different intensity measures are selected and the optimal intensity measure which has the less dispersion is proposed.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.135-136
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• 2022

최근 기후변화의 영향으로 태풍 및 국지성 집중호우 등 자연재해 발생빈도가 증가함에 따라 풍수해로 인한 인명피해와 재산피해가 증가하고 있다. 국내에서는 재해연보를 통해 자연재난 피해이력 통계정보를 제공하고 있으며, 당해연도 자연재해상황을 기간별, 시도별, 수계별, 월별, 원인별 총괄통계와 인명피해, 시설피해와 관련된 피해면적, 피해액, 복구액 등 세부내용으로 구성하여 정보를 제공하고 있다. 행정안전부는 국가재난정보시스템을 통해 취합된 지자체 피해이력 통계자료를 입력하고 있는데 입력하는 과정에서 누락, 오기 등의 오류가 발생할 가능성이 있다. 경제적 손실이 증가하고 있는 풍수해 재난이 발생하게 될 경우 피해비용 집계, 피해액 산정 등 정확한 자료로서 구축되지 않으면 연구 및 분석을 수행하기 위한 통계자료로서 활용될 수 없다. 이러한 문제점을 개선하기 위해서 본 연구에서는 1985년부터 2018년까지 재해연보에 대해서 기간별-시군구별 자료분석을 통해 피해이력 데이터 오류 유형에 대해 분류하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.99-99
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• 2020

The frequency and scale of domestic flood damage continues to increase, but the criteria for responding to flood damage have not been established. To this end, research is underway to estimate the amount of rainfall in each region so that it can be used to respond to flood damage. The limit rainfall is defined as the cumulative maximum rainfall for each duration that causes flooding, and this research purpose to improve the threshold rainfall by estimating the damage based on the damage history in units of 5 years and analyzing changes over time. The limit rainfall based on the damage history was estimated by using the NDMS past damage history of the Ministry of the Interior and Safety and the rainfall minutes data of AWS and ASOS. The period for estimating the limit rainfall is 2013 ~ 2017, 2015 ~ 2019, and the limit rainfall is estimated by analyzing the relationship between the flood damage history and the rainfall event in each period. Considering changes in watershed characteristics and disaster prevention performance, the data were compared using 5-year data. As a result of the analysis, the limit rainfall based on the damage history could be estimated for less than about 10.0% of the administrative dongs nationwide. As a result of comparing the limit rainfall by period, it was confirmed that the area where the limit rainfall has increased or decreased This was analyzed as a change due to rainfall events or urbanization, and it is judged that it will be possible to improve the risk criteria of flooding.