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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 in...

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 objectives simultaneously and to rationally select a well-balanced solution. However, as the number of objectives increases, additional computational efforts are required to obtain the Pareto solutions, for decision-making to select well-balanced solutions, and for visualisation of the solutions. This paper presents a novel approach to multi-objective optimisation process of probabilistic service life management with four objectives: minimising the damage detection delay, minimising the probability of failure, maximising the extended service life and minimising the expected total life-cycle cost. With these four objectives, the single, bi-, tri- and quad...

We consider the problem of full information maximum likelihood (FIML) estimation in factor analysis when a majority of the data values are missing. The expectation–maximization (EM) algorithm is often used to find the FIML estimates, in which the missing values on manifest variables are included in complete data. However, the ordinary EM algorithm has an extremely high computational cost. In this paper, we propose a new algorithm that is based on the EM algorithm but that efficiently computes the FIML estimates. A significant improvement in the computational speed is realized by not treating the missing values on manifest variables as a part of complete data. When there are many missing data values, it is not clear if the FIML procedure can achieve good estimation accuracy. In order to investigate this, we conduct Monte Carlo simulations under a wide variety of sample sizes.

Seismic isolation system (SIS) of building structures can lead to reduction of the structural response to earthquake ground motion and improvement of structural safety. This paper introduces a sliding seismic isolator with mass energy regulator springs (SSIM) as a SIS type, and presents the application procedure of the SSIM to an existing building structure considering the probability that the SIS application leads to cost–benefit, the seismic performance evaluation of the building structure and the efficient SIS inspection after earthquakes. Based on a decision tree considering the probability of earthquake occurrence during the service of a building structure and functionality of the SIS against earthquakes, cost–benefit from installing a SIS is formulated, and, probability that the SIS application leads to cost–benefit is estimated. In the seismic performance evaluation, the fundamental period and structural response acceleration to the horizontal ground motion of the building with the SSIM are assesse...

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 presents a probabilistic approach for combined inspection/monitoring planning for fatigue-sensitive structures considering uncertainties associated with fatigue crack initiation, propagation and damage detection. This combined inspection/monitoring planning is the solution of an optimisation formulation, where the objective is minimising theexpected damage detection delay. Furthermore, this formulation is extended to a bicriterion optimisation considering the conflicting relation between expected damage detection delay and cost. A set of Pareto solutions is obtained by solving this bicriterion optimisation problem. From this set, a solution can be selected balanci...

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 loading on naval high-speed vessels is still a challenge. Potential lifetime load effects including low frequency wave-induced and high frequency slam-induced whipping loadings are investigated in this article by using a probabilistic approach. Clearly, integration of probabilistic sea loads into structural reliability assessment and service life prediction will provide a more reliable estimation of the long-term structural performance. Accordingly, this article presents an approach for fatigue reliability evaluation of ship structures based on the estimated lifetime sea loads. Loading information associated with sea states, ship speeds and relative wave heading...