• 한국안전학회지
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• 제28권5호
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• pp.41-48
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• 2013

This paper is intended to provide the background information and justification for Korean highway bridge design code(limit state design)(2012). Limit state design method calculates reliability index and probability of failure through the analysis of the reliability of the experimental database. It has become possible to perform the economical and consistent design by evaluating the safety of a structure quantitatively. In this paper, we used the design specifications of RC slab bridge of superstructure form of Road Design Manual in Part 5 bridge built in highway bridge. This study conducted structural analysis using the method of frame structure theory, design and analysis of bridge by limit state design method, the design code including various standards and Load model applied Korean highway bridge design code limit state design(KHBDC;2012). As a result, it analyzed the effect of safety through comparison. Showing effect of improvement the safety factor and comparing the value of the result, it is determined to be capable of economical design and safety. Furthermore, limit state design method was able to determine many redundant force of cross-section compared with existing design method. It is determined that it can reduce the overall amount because of the reduction of the cross-section and girder depth.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.28-35
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• 2005

It is now well recognized that the ultimate limit state approach is a much better basis for design and strength assessment of ships and offshore structures since it is difficult to determine the realistic margin of safety using the traditional allowable working stress approach on the basis of linear elastic method solutions together with buckling strengthchecks adjusted by a simple plasticity correction. This paper outlines ALPS theory for ultimate limit state assessment of ship structures. ALPS is a computer software which stands for nonlinear Analysis of Large Plated Structures. Application examples of ALPS program to ultimate limit state assessment of plates, stiffened panels and ship hull girders are presented. A benchmark study is made by a comparison with the ALPS solutions with other methods including class rule formulae, nonlinear finite element methods and experimental results. Future trends on ultimate limit state assessment of ship structures are addresse[1]

• Structural Engineering and Mechanics
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• 제71권2호
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• pp.165-173
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• 2019

This paper investigates the probability of failure of reinforced concrete beams for limit state of collapse for flexure and shear. The influence of randomness of the variables on the failure probability is also examined. The Indian standard code for plain and reinforced concrete IS456:2000 is used for the design of beams. Probabilistic models are developed for flexure and shear according to IS456:2000. The loads considered acting on the beam are live load and dead load only. Random variables associated with the limit state equation such as grade of concrete, grade of steel, live load and dead load are identified. Probability of failure is evaluated based on the limit state equation using First Order Reliability Method (FORM). Importance of the random variables on the limit state equations are observed and the variables are accordingly reduced. The effect of the reduced parameters is checked on the probability of failure. The results show the role of each parameter on the design of beam. Thus, the Indian standard guidelines for plain and reinforced concrete IS456:2000 is investigated with the probabilistic and risk-based analysis and design for a simple beam. The results obtained are also compared with the literature and accordingly some suggestions are made.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.213-223
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• 2017

Bridges are lifeline and integral components of transportation system that are susceptible to seismic actions, their vulnerability assessment is essential for seismic risk assessment and mitigation. The vulnerability assessment of bridges common in Pakistan is very important as it is seismically very active region and the available code for the seismic design of bridges is obsolete. This research presents seismic vulnerability assessment of three real case simply supported multi-span reinforced concrete bridges commonly found in northern Pakistan, having one, two and three bents with circular piers. The vulnerability assessment is carried through the non-linear dynamic time history analyses for the derivation of fragility curves. Finite element based numerical models of the bridges were developed in MIDAS CIVIL (2015) and analyzed through with non-linear dynamic and incremental dynamic analyses, using a suite of bridge-specific natural spectrum compatible ground motion records. Seismic responses of shear key, bearing pad, expansion joint and pier components of each bridges were recorded during analysis and retrieved for performance based analysis. Fragility curves were developed for the bearing pads, shear key, expansion joint and pier of the bridges that first reach ultimate limit state. Dynamic analysis and the derived fragility curves show that ultimate limit state of bearing pads, shear keys and expansion joints of the bridges exceed first, followed by the piers ultimate limit state for all the three bridges. Mean collapse capacities computed for all the components indicated that bearing pads, expansion joints, and shear keys exceed the ultimate limit state at lowest seismic intensities.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.146-153
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• 2004

The goals of this study are to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential for characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve are verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.193-200
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• 1999

Since Broms and Bennermark(1967) suggested the face stability criterion based on laboratory extrusion tests and field observations, the face stability of a tunnel driven in cohesive material has been studied by several authors. And recently, more general solution for the tunnel front is given by Leca and Panet(1988). They adopted a limit state design concept to evaluate the face stability of a shallow tunnel driven into cohesionless material and showed that the calculated upper bound solution represented the actual behavior reasonably well. In this study, two factors are simultaneously considered for assessing tunnel face stability: One is the effective stress acting on the tunnel front calculated by upper bound solution; and the other is the seepage force calculated by numerical analysis under the condition of steady state ground water flow. The model tests were performed to evaluate the seepage force acting on the tunnel front and these results were compared with results of numerical analysis. Consequently, the methodology to evaluate the stability of a tunnel face including limit analysis and seepage analysis is suggested under the condition of steady state ground water flow.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.267-273
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• 2003

Steel fiber may be used to raise the effectiveness and safety of reinforced concrete structure and to relax its brittle-fracture behavior. However it is to be clearly stated that the uncertainty for the strength of fiber reinforced concrete(SFRC) is rather increased. Therefore, it is necessary to evaluate the safety of SFRC beam using reliability analysis incorporating realistic uncertainty. This study presents the statistical data and proposes the limit state model to analyze the reliability of SFRC bear In order to verify the efficiency of the proposed limit state model, its numerical application and sensitivity analysis were performed for a continuous SFRC beam. From the results of the numerical analysis, it is founded that the reliability of SFRC beam is significantly difficult from the conventional RC beams and proposed limit state model (or SFRC beam is more rational compared with that for conventional RC beams. Then it may be stated that the reliability analysis of SFRC beams must be carried out for the development of design criteria and the safety assessment.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.67-82
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• 2010

The beam string structure (BSS) has been widely applied in large span roof structures, while no analytical solutions of BSS were derived for it in the existing literature. In the first part of this paper, calculation formulas of displacement and internal forces were obtained by the Ritz-method for the most commonly used arc-shaped BSS under the vertical uniformly distributed load and the prestressing force. Then, the failure mode of BSS was proposed based on the static equilibrium. On condition the structural stability was reliable, BSS under the uniformly distributed load would fail by tensile strength failure of the string, and the beam remained in the elastic or semi-plastic range. On this basis, the limit load of BSS was given in virtue of the elastic solutions. In order to verify the linear elastic and limit state solutions proposed in this paper, three BSS modal were tested and the corresponding elastoplastic large deformation analysis was performed by the ANSYS program. The proposed failure mode of BSS was proved to be correct, and the analytical results for the linear elastic and limit state were in good agreement with the experimental and FEM results.

• Structural Engineering and Mechanics
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• 제38권5호
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• pp.651-674
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• 2011

This paper presents a novel method for predicting the failure probability of structural or mechanical systems subjected to random loads and material properties involving multiple design points. The method involves Multicut High Dimensional Model Representation (Multicut-HDMR) technique in conjunction with moving least squares to approximate the original implicit limit state/performance function with an explicit function. Depending on the order chosen sometimes truncated Cut-HDMR expansion is unable to approximate the original implicit limit state/performance function when multiple design points exist on the limit state/performance function or when the problem domain is large. Multicut-HDMR addresses this problem by using multiple reference points to improve accuracy of the approximate limit state/performance function. Numerical examples show the accuracy and efficiency of the proposed approach in estimating the failure probability.

• 한국터널지하공간학회 논문집
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• 제20권1호
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• pp.99-118
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• 2018

최근 토목구조물의 설계에 있어 한계상태설계법 적용이 세계적인 추세이나, 국내에서는 소수의 구조물에 국한되어 사용되고 있다. 주요 지중구조물인 터널에 대해서는 한계상태설계법의 도입이 근래에 시도되고 있으므로, 최신의 한계상태 설계법에 대한 이해가 반드시 필요하다. 본 연구는 최근 발간된 AASHTO LRFD Road Tunnel Design and Construction Guide Specification (2017)을 토대로 세그먼트 터널라이닝 설계 시 구조물 하중계수, 하중조합 등을 고찰하고 이외에 구조 검토 시 반영되어야 할 다양한 영향인자에 대해 분석하였다. 본 연구에서는 국내에 적용되고 있는 전력구, 지하철 터널 단면을 대상으로 한 세그먼트 라이닝의 구조해석을 통하여, 지반조건과 하중수정계수, 이음부 강성조건 등 다양한 영향인자들이 부재력에 미치는 영향을 분석 평가하였다.