• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.53-64
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• 2018

In this study, the evaluation to probability of failure for risk assessment of port structures on DCM reinforced soils, where stability and risk assessment are increasing in importance, was performed. As a random variables affecting the risk of DCM improved ground, the design strength, superposition (overlap) of construction, strength of the natural ground, internal friction angle and unit weight of the modified ground were selected and applied to the risk assessment. In addition, the failure probability for the entire system under ordinary conditions and under earthquake conditions were analyzed. As a result, it was found that the highest coefficient of variation in the random variable for the risk assessment of the DCM improved ground is the design strength, but this does not have a great influence on the safety factor, ie, the risk of the system. The main risk factor for the failure probability of the system for the DCM reinforced soils was evaluated as horizontal sliding in case of external stability and compression failure in case of internal stability both at ordinary condition and earthquake condition. In addition, the failure probability for ordinary horizontal sliding is higher than that for earthquake failure, and the failure probability for ordinary compression failure is lower than that for earthquake failure. The ordinary failure probability of the entire system is similar to the failure probability on earthquake condition, but in this case, the risk of earthquake is somewhat higher.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.93-102
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• 2011

In spite of being unable to take into the effect of intermediate principal stress, Mohr-Coulomb and Hoek-Brown criteria are very popular as rock failure criteria. The recent researches reveal that the influence of intermediate principal stress on the failure strength of rock is substantial, so that 3-D failure criteria in which the intermediate principal stress could be considered is necessary for the safe design of the important rock structures. In this study, the likely application of the 3-D failure criterion proposed by Jiang & Pietruszczak (1988) to the prediction of the true triaxial strength of rock materials is discussed. The failure condition is linear in the meridian plane of principal stress space and it is represented by the smooth surface contacting the corners of the Mohr-Coulomb surface. The performance of the Jiang & Pietruszczak's criterion is demonstrated by simulating the actual true triaxial tests on the rock samples of three different rock types.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.108-115
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• 2003

Bridges are rated at two levels by either Load Factor Design (LFD) or Allowable Stress Design (ASD). The lower level rating is called Inventory Rating and the upper level rating is called Operating Rating. To maintain bridges effectively, there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life from a system reliability viewpoint. The lifetime functions are introduced and explained to predict the time-dependent failure probability. The bridge studied in this paper was built 30 years ago in rural area. For this bridge, the load test and rehabilitation were conducted. The time-dependent system failure probability is predicted with or without rehabilitation. As a case study, an optional rehabilitation is suggested, and fir this rehabilitation, load rating is computed and the time-dependent system failure probability is predicted. Based on rehabilitation costs and extended service lifes, the optimal rehabilitation is suggested.

• Geotechnical Engineering
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• v.7 no.3
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• pp.21-32
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• 1991

The purpose of this paper is to develop a reliability model for slope stability of Earth-rockfill dams which accounts for all uncertainties encountered. The uncertain factors of the design variables include the cohesion, the angle of internal friction, and the porewater Pressure in each zone. More specifically, the model errors in estimating those variables are studied in depth. To reduce the uncertainties due to model errors, updated design variables are obtained using Bayesian Theory. For stability analysis, both the two-dimesional stability analysis and the three-dimensional stability analysis where the end effects and the system reliability concept are considered are used for the reliability calculations. The deterministic safety factor by the three-dimensional analysis is lager than that by the two-dimensional anlysis. However, the probability of failure by the three-dimensional analysis is about 3.5 times larger that by the two-dimensional analysis. It is because the system reliability concept is used in the three-dimensional analysis. The sensitivity analysis shows that the probability of failure is more sensitive to the uncertainty of the cohesion than that of the angle of internal friction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.145-151
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• 2009

The span deflection among the monitoring items of bridge measurement system in real time is representative behaviour and important index of superstructure condition. the limit of span deflection in Standard Specifications for Highway Bridge in Korea has been applied to the method that is making the management-criteria for span deflection in bridge measurement system. But the limit concern mainly serviceability of divers. So it is difficult to find the safety factor of the limit from the viewpoint of bridge safety. This study estimated the safety factor of the limit of span-deflection in Standard Specifications for Highway Bridge in Korea from the viewpoint of bridge safety by the indoor structural test.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.355-362
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• 2008

A reliability model of Level II AFDA is proposed to analyze the wave run-up occurring by the interaction of incident waves and sloped coastal structures. The reliability model may be satisfactorily calibrated by Level III Monte-Carlo simulation. Additionally, the partial safety factors of random variables related to wave run-up can be straightforwardly evaluated by the inverse-reliability method that use influence coefficients and uncertainties of random variables, and target probability of failure. In particular, a design equation for wave run-up is derived in the same form as that of deterministic design method so that the reliability-based design method of Level I may be applied easily. Finally, it is confirmed that results redesigned by the reliability-based design method of Level I with partial safety factors suggested in this paper are satisfactorily compared with results of CEM(2006) as well as those of Level II AFDA.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.117-120
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• 2008

The bridge bearings are devices absorbing the displacements of the superstructure. KS F 4420 relative to the design of elastomeric bearings in Korea allows shear deformation up to 70% of total rubber height. For the elastomeric bearings to fulfill their shear function required in the design, the stability of allowable shear strain of elastomeric bearings relative to the shear failure should be guaranteed. Moreover considering the possibility that elastomeric bearings are applied to the seismic design together with isolation devices, elastomeric bearings is supposed to display higher shear performance. In this paper ultimate shear performance tests were performed. The measured ultimate shear strains were over 200%. Therefore an allowable shear strain provision becomes safe. But elastomeric bearings expected to show their performance in one united body reveled the separation of components near 200% shear strain. These separation in elastomeric bearing can cause unexpected impact or concentrated stress to bridge system considering to application of seismic design. Therefore provision relevant to separation problem is necessary.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.657-671
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• 2023

As large-scale earthquakes have occurred in Korea and their aftermath continues to be felt, laws and regulations on seismic design have been emphasized, and in Korea, the seismic design standards have been newly revised after the Gyeongju earthquake. In the revised seismic design standards, a stability review for the destruction of the support activity of the breakwater was newly added. Therefore, in this study, we conducted a stability analysis on the seismic reinforcement method for the study site, and checked the ground acceleration of the subgrade and the displacement of the structure over time. As a result of the stability analysis, the safety factor increased by at least 0.5 and up to 1.7. As a result of the time history analysis, the displacement of the superstructure decreased by up to 290 mm and down to 12 mm in both the shallow and deep sections before and after reinforcement, and the ground acceleration decreased by up to 5.33 m/s and down to 0.31 m/s after reinforcement.

• Journal of Korean Association for Spatial Structures
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• v.10 no.1
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• pp.85-93
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• 2010

This paper suggests a vibration control method long span structures with trussed roof. Basic concept of this method is based on the energy absorption through hysteresis loop of an elasto-plastic element. This element is attached on the top of the column supporting the roof. Two different types of roofs and three of earthquake waves are used in the investigation. It shows that this is very efficient method to reduce the seismic energy of roof member transferred from the column.

• Proceedings of the KIEE Conference
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• summer
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• pp.971-973
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• 2004

본 논문에서는, 초고압 GIS(Gas Insulated Switchgear)용 GCB(Gas Circuit Breaker)의 3상 배치구조 설계를 위한 상간, 극간, 대지간의 절연성능을 평가하였다. 뇌임펄스 전압과 상용주파 전압인가 시 상간, 극간, 대지간의 절연설계 기준을 근거로 절연설계 안전율을 고려하여 설계에 적용하였다. 수치적 전계 해석법으로 3차원 전계 해석법과 2차원 축대칭 해석법을 이용하였으며 절연설계 여유율과 현장에서의 절연파괴 시험을 통한 데이타와 비교 분석하였으며, 분석한 결과 절연설계 기준에 적합한 상배치 구조 설계임을 확인하였다.