• Earthquakes and Structures
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• v.7 no.3
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• pp.251-269
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• 2014

To investigate the seismic performance and to obtain quantitative parameters for the requirement of performance-based bridge seismic design approach, 12 reinforced concrete (RC) hollow rectangular bridge column specimens were tested under constant axial load and cyclic bending. Parametric study is carried out on axial load ratio, aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. The damage states of these column specimens were related to engineering limit states to determine the quantitative criteria of performance-based bridge seismic design. The hysteretic behavior of bridge column specimens was simulated based on the fiber model in OpenSees program and the results of the force-displacement hysteretic curves were well agreed with the experimental results. The damage states of residual cracking, cover spalling, and core crushing could be well related to engineering limit states, such as longitudinal tensile strains of reinforcement or compressive strains of concrete, etc. using cumulative probability curves. The ductility coefficient varying from 3.71 to 8.29, and the equivalent viscous damping ratio varying from 0.19 to 0.31 could meet the requirements of seismic design.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.61-65
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• 2008

Urban flooding with surcharges in sewer system was investigated because of unexpected torrential storm events these days, causing significant amounts of human and economic damages. Although there are limitations in forecasting and preventing natural disasters, integrated urban flooding management system using the SWMM engine and Web technology will be an effective tool in securing safety in operating Bi-modal transportation system. In addition, the integrated urban flooding management system can be linked with general and transportation-related disaster management system in the future. In this study, With simulated values by the SWMM, which is a core engine of the Bi-modal disaster management system, flash flooding area estimation module was developed. Thus, the SWMM system codes were modified and new module was developed and integrated with the existing SWMM interface using the Delphi programming language. The flash flooding area estimation module is fully integrated with the SWMM interface, thus the area is estimated on-the-fly inside the system.

• Structural Engineering and Mechanics
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• v.71 no.6
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• pp.683-697
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• 2019

The reinforced concrete (RC) structures usually suffer large residual displacements under strong motions. The large residual displacements may substantially reduce the anti-seismic capacity of structures during the aftershock and increase the difficulty and cost of structural repair after an earthquake. To reduce the adverse residual displacement, several self-centering energy dissipation braces (SCEBs) have been proposed to be installed to the RC structures. To investigate the seismic responses of the RC structures with SCEBs under the earthquake excitation, an extended Bouc-Wen model with degradation and self-centering effects is developed in this study. The extended model realized by MATLAB/Simulink program is able to capture the hysteretic characteristics of the RC structures with SCEBs, such as the energy dissipation and the degradation, especially the self-centering effect. The predicted hysteretic behavior of the RC structures with SCEBs based on the extended model, which used the unscented Kalman filter (UKF) for parameter identification, is compared with the experimental results. Comparison results show that the predicted hysteretic curves can be in good agreement with the experimental results. The nonlinear dynamic analyses using the extended model are then carried out to explore the seismic performance of the RC structures with SCEBs. The analysis results demonstrate that the SCEB can effectively reduce the residual displacements of the RC structures, but slightly increase the acceleration.

• Earthquakes and Structures
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• v.16 no.6
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• pp.641-654
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• 2019

This paper investigates the seismic response of a typical non-navigable continuous girder bridge isolated with friction sliding bearings of the Hong Kong-Zhuhai-Macao link projects in China. The effectiveness of the friction pendulum system (FPS) and accuracy of the numerical model were evaluated by a 1/20 scaled bridge model using shaking table tests. Based on the hysteretic properties of friction pendulum system (FPS), double concave friction pendulum (DCFP), and triple friction pendulum system (TFPS), seismic response analyses of isolated bridges with the three sliding-type bearings are systematically carried out considering soil-pile interaction under offshore soft clay conditions. The fast nonlinear analysis (FNA) method and response spectrum are employed to investigate the seismic response of isolated offshore bridge structures. The numerical results show that the implementation of the three sliding-type bearings effectively reduce the base shear and bending moment of the reinforced concrete pier, at the cost of increasing the absolute displacement of the bridge superstructure. Furthermore, the TFPS and DCFP bearings show better isolation effect than FPS bearing for the example continuous girder bridge.

• Geomechanics and Engineering
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• v.37 no.1
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• pp.1-8
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• 2024

Buckling failure is one of the classical types of catastrophic landslides developing on inclination-paralleled rock slopes, which is mainly governed by its self-weight, earthquake and ground water. However, nearly none of the existing studies fully consider the influence of slope self-weight, earthquake and ground water on the mechanical model of buckling failure. In this paper, based on energy equilibrium principle and elastoplastic slab theory, a thorough mechanical analysis on bucking slopes has been carried out. Furthermore, an analytical solution for slip bucking failure of rock slopes has been proposed, which fully considers the effect of slope self-weight, seismic force and hydrostatic pressure. Finally, the methodology is used to conduct comparative analysis with other analytical solutions for three practical buckling studies. The results show that the proposed approach is capable of providing a more accurate and reasonable evaluation for stability of rock slopes with potential buckling failure.

• Journal of Korea Water Resources Association
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• v.52 no.12
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• pp.963-973
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• 2019

This study reviews a urban flooding risk criteria estimation model to predict risk criteria in areas where flood risk criteria are not precalculated by using watershed characteristic data and limit rainfall based on damage history. The risk criteria estimation model was designed using Support Vector Machine, one of the machine learning algorithms. The learning data consisted of regional limit rainfall and watershed characteristic. The learning data were applied to the SVM algorithm after normalization. We calculated the mean absolute error and standard deviation using Leave-One-Out and K-fold cross-validation algorithms and evaluated the performance of the model. In Leave-One-Out, models with small standard deviation were selected as the optimal model, and models with less folds were selected in the K-fold. The average accuracy of the selected models by rainfall duration is over 80%, suggesting that SVM can be used to estimate flooding risk criteria.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.413-421
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• 2017

This study intends to conduct a thorough research and analysis on the designated temporary residential facilities for the disaster victims in order to bridge the gap between the temporary residential facilities for the disaster victims in country and city, and understand the current status of the designated temporary residential facilities for the disaster victims in rural and urban areas. As a result, the designated temporary residential facilities for the disaster victims in urban areas are bigger and have higher capacity, implying the necessity to designate facilities in rural areas that can accommodate larger number of people. As to the analysis of the representative temporary residential facilities for the disaster victims in rural areas, different regions had different types of designated facilities and the number of facilities also showed big difference depending on regions. So it is believed that local governments should improve the process and system of designating temporary residential facilities for the disaster victims.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.599-608
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• 2018

As natural disasters are increasing due to the unusual weather and the modern society is getting complicated, the rapid change of the urban environment has increased human disasters. Thus, citizens are becoming more anxious about social safety. The importance of preparation for safety has been suggested by providing the disaster safety services such as regional safety index, life safety map, and disaster safety portal application. In this paper, we propose an application framework to predict the urban safety index based on user's location with realtime weather/atmosphere data after creating a predication model based on the machine learning using number of occurrence cases and weather/atmosphere history data. Also, we implement an application to provide traffic safety index with executing preprocessing occurrence cases of traffic and weather/atmosphere data. The existing regional safety index, which is displayed on the Si-gun-gu area, has been mainly utilized to establish safety plans for districts vulnerable to national policies on safety. The proposed system has an advantage to service useful information to citizens by providing urban safety index based on location of interests and current position with realtime related data.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.1-11
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• 2010

In this study, we studied strategic directions of urban management through evaluation the value of the investment with the consideration of the development plan, the condition of the location, the potential of the site, green and disaster prevention infrastructure, focused on Gugal-dong(Gugal Station area) and the region of Bora, Jung-dong, in Yongin city. In terms of the methodology, we tried to decide using Analytic Network Process which can consider the relation between the evaluation items. In conclusion, for the development plan, the order of evaluation items is development purpose, key tenant, fund raising and marketing, and for the condition of the location, the order of evaluation items is land use, surrounding environment, and traffic environment, and for the development potential, the order is marketability, identity, and historic character, and for the green and disaster prevention infrastructure, the order is prevention of human, natural, social disaster. The significance of the conclusion of this study is that it can be utilized in pre-evaluation in planning the urban development.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1209-1213
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• 2005

It reflects well feature of slope that is characteristic of city river basin of Pusan local. Process various hydrological datas and basin details datas which is collected through basin basis data. weather satellite equipment(EMS-DEU) and automatic water level equipment(AWS-DEU) and use as basin input data of ILLUDAS model, SWMM model and HEC-HMS model In order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS model. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS model and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed imagination reservoir(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.