• Structural Monitoring and Maintenance
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• 제9권4호
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• pp.337-357
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• 2022

The objective of this study is to present a data-driven machine learning (ML) framework for predicting ultimate shear strength and failure modes of reinforced concrete ledge beams. Experimental tests were collected on these beams with different loading, geometric and material properties. The database was analyzed using different ML algorithms including decision trees, discriminant analysis, support vector machine, logistic regression, nearest neighbors, naïve bayes, ensemble and artificial neural networks to identify the governing and critical parameters of reinforced concrete ledge beams. The results showed that ML framework can effectively identify the failure mode of these beams either web shear failure, flexural failure or ledge failure. ML framework can also derive equations for predicting the ultimate shear strength for each failure mode. A comparison of the ultimate shear strength of ledge failure was conducted between the experimental results and the results from the proposed equations and the design equations used by international codes. These comparisons indicated that the proposed ML equations predict the ultimate shear strength of reinforced concrete ledge beams better than the design equations of AASHTO LRFD-2020 or PCI-2020.

• Industrial Engineering and Management Systems
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• 제4권2호
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• pp.207-217
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• 2005

Business mergers are a direct result of rapid changes in the current corporate environment. They are occurring in many industries, including financial institutions. As information systems prove increasingly indispensable in the integration of companies’ business systems, information system integration is becoming increasingly necessary. However, in many cases such integration does not work well. Therefore, this paper proposes a new framework using both IS integration model and IS integration phases to analyze systems failure in IS integration.

• 한국건설관리학회논문집
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• 제13권3호
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• pp.78-88
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• 2012

국내의 건설실패 관련 연구는 체계화된 실패정보 분류체계 및 실패정보의 활용을 위한 방안을 제시하는 것에 초점을 맞추고 있다. 그러나, 건설현장의 한정된 관리자가 건설실패를 유발하는 다양한 원인에 대한 예방대책을 수립하는 것은 한계가 있다. 따라서, 효율적인 건설실패 예방활동이 이루지기 위해서는 많은 실패원인에 대한 정량적 평가를 통해 우선순위를 정하여 효율적인 예방대책이 수립되어야 한다. 이에 본 연구는 정량적인 평가를 통해 실패를 유발하는 핵심관리요인을 도출 할 수 있도록 FMEA(Failure Mode and Effect Analysis) 기법을 활용한 건설실패 핵심관리요인 선정방법을 제시하고, 공동주택 골조공사를 대상으로 핵심관리요인을 분석하는 것을 목적으로 하였다. 이를 위해 FMEA 기법의 위험도를 실패 위험성과 예방성으로 구분하여 평가할 수 있도록 하였다. 본 연구에서 제시한 핵심관리요인 평가방법은 건설실패의 사전예방대책을 효율적으로 수립하는데 활용될 수 있으며, 향후 유사한 연구를 통해 프로젝트 수행 단계별 혹은 다양한 시설 및 공종에 대한 핵심관리요인을 도출하는데 활용될 수 있을 것으로 기대된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.135-142
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• 2000

A framework alternative to that of classical slope stability analysis is developed, wherein the soil mass is treated as a continuum and in situ soil stresses and strengths are computed accurately using inelastic finite element methods with general constitutive models. Within this framework, two alternative methods of stability analysis are presented. In the first, the strength characteristics of the soil mass are held constant, and the gravitational loading on the slope system is increased until failure is initiated by well-defined mechanisms. In the second approach, the gravity loading on the slope system is held constant, while the strength parameters of the slope mass are gradually decreased until well-defined failure mechanisms developed. Details on the applying both of the proposed methods, and comparisons of their characteristics on a number of solved example problems are presented.

• 한국안전학회지
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• 제31권5호
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• pp.95-101
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• 2016

This study proposes a multi-scale dynamic system reliability analysis of control system as a method of quantitative evaluation of its performance in probabilistic terms. In this second paper, we discuss the control effect of the viscous damper on the seismic performance of the structure-level failure. Since the failure of one structural member does not necessarily cause the collapse of the structural system, we need to consider a set of failure scenarios of the structural system and compute the sum of the failure probabilities of the failure scenarios where the statistical dependence between the failure scenarios should be taken into account. Therefore, this computation requires additional system reliability analysis. As a result, the proposed approach takes a hierarchial framework where the failure probability of a structural member is computed using a lower-scale system reliability with the union set of time-sequential member failures and their statistical dependence, and the failure probability of the structural system is again computed using a higher-scale system reliability with the member failure probabilities obtained by the lower-scale system reliability and their statistical dependence. Numerical results demonstrate that the proposed approach can provide an accurate and stable reliability assessment of the control performance of the viscous damper system on the system failure. Also, the parametric study of damper capacity on the seismic performance has been performed to demonstrate the applicability of the proposed approach through the probabilistic assessment of the seismic performance improvement of the damper system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.358-361
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• 1996

In this paper, we discuss decentralized optimal fault tolerant supervisory control issues on the basis of failure analysis and diagnosis from the angle of discrete event dynamic system. We address the detectability and the observability problems, and develope fault tolerant supervisory control system upon the failure analysis and diagnosis schemes. A complete min-cut is introduced and the procedure for finding the achievable or nonachievable layered optimal legal sublanguages is suggested for a preferential option among the reachable states in the controlled plant. A layered optimal supervisory control framework is proposed upon these. We extend the concept of decentralized supervisory control by considering the problem of combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable pair and present a hybrid decentralized supervisory control framework. Finally, we propose the analytical framework for a decentralized optimal fault tolerant supervisory control systems.

• Structural Engineering and Mechanics
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• 제35권5호
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• pp.571-592
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• 2010

An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial, bending and shear fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In the first part of this study, energy expressions that construct the constitutive law are equated in the form of total strain energy and the distortion energy dissipated in a fatigue cycle. The resulting equation is further evaluated to acquire the equivalent stress per cycle using energy based methodologies. The equivalent stress expressions are developed both for biaxial and multiaxial fatigue loads and are used to predict the number of cycles to failure based on previously developed prediction criterion. The equivalent stress expressions developed in this study are further used in a new finite element procedure to predict the fatigue life for two and three dimensional structures. In the second part of this study, a new Quadrilateral fatigue finite element is developed through integration of constitutive law into minimum potential energy formulation. This new QUAD-4 element is capable of simulating biaxial fatigue problems. The final output of this finite element analysis both using equivalent stress approach and using the new QUAD-4 fatigue element, is in the form of number of cycles to failure for each element on a scale in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure at each location in gas turbine engine structural components. In order to obtain experimental data for comparison, an Al6061-T6 plate is tested using a previously developed vibration based testing framework. The finite element analysis is performed for Al6061-T6 aluminum and the results are compared with experimental results.

• Geomechanics and Engineering
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• 제11권6호
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• pp.867-877
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• 2016

Collapse shape of tunnel roof in layered Hoek-Brown rock media is investigated within the framework of upper bound theorem. The traditional collapse mechanism for homogeneous stratum is no longer suitable for the present analysis of roof stability, and it would be necessary to propose a curve failure mode to describe the velocity discontinuity surface in layered media. What is discussed in the paper is that the failure mechanism of tunnel roofs, consisting of two different functions, is proposed for layered rock media. Then it is employed to investigate the impending roof failure. Based on the nonlinear Hoek-Brown failure criterion, the collapse volume of roof blocks are derived with the upper bound theorem and variational principle. Numerical calculations and parametric analysis are carried out to illustrate the effects of different parameters on the shape of failure mechanism, which is of overriding significance to the stability analysis of tunnel roof in layered rock media.

• Journal of Electrical Engineering and Technology
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• 제1권4호
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• pp.414-422
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• 2006

Deterministic techniques have been applied in power system planning for many years and there is a growing interest in combining these techniques with probabilistic considerations to assess the increased system stress due to the restructured electricity environment. The overall reliability framework proposed in this paper incorporates the deterministic N-1 criterion in a probabilistic framework, and results in the joint inclusion of both adequacy and security considerations in system planning. The combined framework is achieved using system well-being analysis and traditional adequacy assessment. System well-being analysis is used to quantify the degree of N-1 security and N-1 insecurity in terms of probabilities and frequencies. Traditional adequacy assessment is Incorporated to quantify the magnitude of the severity and consequences associated with system failure. The concepts are illustrated by application to two test systems. The results based on the overall reliability analysis framework indicate that adequacy indices are adversely affected by a generation deficient environment and security indices are adversely affected by a transmission deficient environment. The combined adequacy and security framework presented in this paper can assist system planners to realize the overall benefits associated with system modifications based on the degree of adequacy and security, and therefore facilitate the decision making process.

• Structural Engineering and Mechanics
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• 제35권6호
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• pp.659-676
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• 2010

An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial and bending fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In this study, the energy expressions that construct the new constitutive law are integrated into minimum potential energy formulation to develop new finite elements for uniaxial and bending fatigue life prediction. The comparison of finite element method (FEM) results to existing experimental fatigue data, verifies the new finite elements for fatigue life prediction. The final output of this finite element analysis is in the form of number of cycles to failure for each element in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure for each element in structural components. The performance of the fatigue finite elements is demonstrated by the fatigue life predictions from Al6061-T6 aluminum and Ti-6Al-4V. Results are compared with experimental results and analytical predictions.