Sunyong Kim

• Ph.D.
• Wonkwang University

This paper presents a novel probabilistic approach for optimum combined inspection and monitoring planning (CIMP) with updating. This optimum planning is based on five objectives considering life-cycle cost, extended service life, maintenance delay, damage detection delay, and time-based probability of failure. The five-objective optimization provi...

Structural health monitoring (SHM) provides relevant information on structural health prognosis for existing structures. This information can be used to improve the accuracy associated with structural performance prediction, and lead to more rational life-cycle management of civil infrastructure systems under uncertainty. This chapter presents the...

The performance and remaining service life of deteriorating reinforced concrete (RC) structures decrease with time due to increased critical damage propagation based on coupled corrosion and fatigue. Since damage propagation prediction is highly uncertain, an updating process after each inspection and monitoring is required to improve the accuracy...

In order to ensure structural safety, deteriorating bridges should be maintained above their target reliability level. This level affects the optimum maintenance interventions during the service life of a bridge. Therefore, it is necessary to determine the target reliability level of an individual bridge in a rational way. This paper introduces a n...

Effective life-cycle management of deteriorating structures should be based on an accurate and reliable damage propagation prediction model under uncertainty. Appropriate updating with inspected information can decrease errors between the detected and predicted damage and finally improve the accuracy and reliability of life-cycle management of a de...

Over the past decades, significant advances have been accomplished in developing SHM techniques to detect the existing damages in deteriorating structures and maintenance techniques to extend the service life of these structures. The application of SHM can lead to more accurate damage detection. By using the information obtained from SHM, the uncer...

Optimum inspection and maintenance planning is essential for the successful management of deteriorating structures. The reliability and accuracy of inspection and maintenance planning can be significantly improved by integrating new information obtained from inspections. For this reason, the inspection and maintenance planning should include an upd...

Probabilistic service life management of a deteriorating structure subjected to fatigue is a systemic process of assessing and predicting its structural performance, and establishing the optimum inspection and repair plans under uncertainty. In order to consider multiple objectives for optimum inspection and repair planning simultaneously, it is ne...

Effective and efficient service life management is essential for a deteriorating structure to ensure its structural safety and extend its service life. The difficulties encountered in the service life management are due to the uncertainties associated with detecting and identifying structural damages, and assessing and predicting the structural per...

The inspection and maintenance plans to ensure the structural safety and extend the service life of deteriorating structures can be established effectively through an optimisation process. When several objectives are required for inspection and maintenance strategies, a multi-objective optimisation process needs to be used in order to consider all...

Engineering structures including civil infrastructures require a life-cycle cost and benefit during their service lives. The service life of a structure can be extended through appropriate inspection and maintenance actions. In general, this service life extension requires more life-cycle cost and cumulative benefit. For this reason, structure mana...

The assessment and prediction of service life of a structure are usually under uncertainty so that rational probabilistic concepts and methods have to be applied. Based on these rational assessment and prediction, optimum maintenance strategies to minimize the life-cycle cost and/or maximize the structural safety can be established. The service lif...

Efficient prognosis based on structural health monitoring (SHM) information can improve the accuracy associated with structural performance assessment and prediction, and lead to more rational life-cycle management of civil infrastructure systems. This chapter deals with the statistical and probabilistic aspects for efficient prognosis using SHM da...

Inspection planning of fatigue sensitive bridges is a complex process. This, in part, is due to various uncertainties associated with the damage propagation and the detection technique used to perform inspections. The planning process starts with identifying the most critical locations of fatigue damage occurrence. In this context, non-destructive...

This paper proposes a generalized probabilistic framework for optimum inspection and maintenance planning of deteriorating structures. The proposed framework covers (1) the damage occurrence and propagation and service life prediction under uncertainty, (2) the relation between degree of damage and probability of damage detection of an inspection m...

Initiation and propagation of fatigue cracks in steel structures induced by repetitive actions are highly random due to both aleatory and epistemic uncertainties related to material properties, loads, damage, modelling and other factors. For this reason, a probabilistic approach is necessary to predict the fatigue crack growth damage. This study pr...

This paper presents an approach for optimum structural damage detection planning under uncertainty. The uncertainties associated with damage occurrence, propagation and inspection are considered in the proposed approach. Optimum damage detection plan is a solution of a bi-objective optimization under uncertainty consisting in simultaneously minimiz...

The optimal decisions to maintain or improve the reliability and functionality of structures and infrastructure systems can only be achieved through proper integrated management planning in a life-cycle comprehensive framework. Structure and Infrastructure Engineering (SIE) is an international journal dedicated to recent advances inmaintenance, man...

In the field of Naval Engineering, the use of life-cycle analyses associated with the concept of aging and time-dependent reliability has gained momentum lately. In this regard, the U.S. Office of Naval Research supports a pro-ject at Lehigh University focused on the development of an integrated life-cycle framework for ship reliability as-sessment...

Timely maintenance actions on deteriorating structures depend on the quality of the non-destructive testing (NDT) method. Damage detection with less delay can lead to less maintenance delay. The efforts to detect existing fatigue cracks and predict fatigue crack propagation reliably will contribute to reduce the damage detection delay, and furtherm...

Repair actions are generally used to prevent failures and to maintain or extend the lifetime of deteriorating structures. To establish optimum inspection/repair planning for a structure, its performance under uncertainty should be assessed and predicted using probabilistic concepts and methods. This paper presents such an approach applied to deteri...

Inspection and monitoring of deteriorating structures are generally performed to assess structural integrity and predict the remaining service life. For deteriorating structures, a reliable prediction of damage occurrence and the time-dependent damage evaluation depend on the accuracy of deterioration models under uncertainty. A probabilistic appro...

The deterioration mechanism of reinforced concrete (RC) structures under corrosion is highly dependent on environment and material properties. Uncertainties in structural damage occurrence and propagation due to corrosion should be considered in a rational way using a probabilistic approach. In this study, such an approach is proposed to establish...

Fatigue is one of the main factors which can produce cracks, and lead to failure of ships. For these structures, damage occurrence and propagation due to fatigue are affected by the action of sea water waves and the sea environment as well as operation, fabrication, and modeling of ship structures under uncertainties. In order to efficiently mainta...

The present paper collects a body of scientific results obtained at Lehigh University, under the sponsorship of the U.S. Office of Naval Research. The aim of the entire research project was to build a general framework for the probabilistic analysis of ship structures in terms of reliability, redundancy, fatigue, material deterioration, damage dete...

Application of maintenance to extend the service life of civil structures is an important issue for civil structure managers. In order to establish an optimal maintenance strategy under uncertainty, it is essential to understand the concept of service life based on reliability of structures. In this chapter, concepts and applications of structural...

This article focuses on estimating probabilistic lifetime sea loads for high-speed ship structures with the aim of assessing fatigue performance and predicting service life from available data. Performance assessment and service life prediction for naval ship structures are extremely important issues. In particular, understanding the effect of sea...

Visual inspections, diagnostic instrumentation and monitoring of bridges are essential for determination of intervention planning. Nowadays, a great challenge is to use bridge monitoring to determine optimal maintenance strategies. Indeed, monitoring data allow updating the knowledge on the structural performance and can significantly affect the in...

Recently, the effective use of information from structural health monitoring (SHM) has been considered as a significant tool for rational maintenance planning of deteriorating structures. Since a realistic maintenance plan for civil infrastructure has to include uncertainty, reliable information from SHM should be used systematically. Continuous mo...

The state of a structural system subjected to deterioration processes is changing continuously. This state cannot be reliably predicted without considering both aleatory and epistemic uncertainties. To reduce the epistemic uncertainty, inspection and structural health monitoring (SHM) should be performed, and the performance prediction model should...

This paper presents two approaches to implement cost-effective structural health monitoring. The first approach is based on the relation between monitoring cost and time-dependent reliability importance of a structural component. The monitoring cost is allocated to individual components according to their reliability importance factors. This alloca...

A novel approach to evaluating safety of existing bridges based on monitored structural responses and component conditions is presented in this paper. A limit state equation is developed for the measured strain data from structural health monitoring (SHM). The new concepts of the condition function, (s,t), and prediction function, (s,t), are introd...

Based on the long-term monitored strain data induced by heavy vehicle traffic on an existing bridge, this paper presents an efficient approach to assessing the bridge system performance through a series-parallel system model consisting of bridge component reliabilities. The correlations among the bridge component safety margins are obtained by usin...

The reliability and performance assessment of engineering structures by monitoring systems in its nature is a complex challenge, since not only a couple of physical quantities, such as material strength properties, environmental conditions, and local stresses but the comprehensive time dependent behavior of structures are of interest. This behavior...

Engineering structures are subjected to time-dependent loading and strength degradation processes. The main purpose of both designer and owner is to keep these processes under control. Several numerical approaches based on mechanical, physical, chemical or combined models have been recently proposed to describe time-dependent processes of engineeri...

Sensors of modern monitoring systems used in structural engineering provide data used for reliability assessment and maintenance planning. The storage and evaluation of sensor information are space and time-consuming activities. Therefore, it is necessary to process only the monitored data indicating a violation of defined performance thresholds. H...

During the past decade, monitoring concepts for structural systems have been subjected to a rapid development process. They have become more and more important in the intervention planning (e.g., maintenance, repair, rehabilitation, replacement) on new and existing structures. Nevertheless, there is still a strong need for the efficient use of stru...