Reliability assessment of structures using interval uncertainty analysis

OWT (Offshore Wind Turbine) support structures are exposed to harsh ocean environment with significant uncertainties in soil properties and environmental loads. Reliability assessment of OWT support structures taking into account those uncertainties is crucial in the development of more cost-effective OWT support structures. This paper presents a state-of-the-art reliability assessment of OWT support structures, providing a comprehensive review on the structural reliability, reliability-based calibration of codes, fatigue reliability and the implementation of reliability assessment. The current and future developments of reliability assessment of OWT support structures, such as reliability-based design optimisation, multi-hazard reliability analysis and risk-based inspection, are also presented. This paper has been written for both 1) researchers new to this research area through providing a comprehensive review on the latest research and summarising underlying theory; and 2) experts in this research area through presenting a comprehensive list of relevant references where the details of analysis methods can be acquired.

Dynamic reliability assessment of nonlinear structures using extreme value distribution based on L-moments

Reliability assessment and performance improvement of long-span roof structure subjected to coupled wind-snow multi-hazard

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An improved steel sheet pile (SSP) inspection procedure is proposed in this paper, which couples the field inspection condition-index methodology previously developed by the U.S. Army Corps of Engineers with reliability assessments to quantify the life-cycle costs and environmental impacts associated with various maintenance and repair (M&R) scenarios. Maintenance and repair strategies over the analysis period (from present to the end of the structure’s lifetime) are determined through reliability assessment for structures with relatively low condition indices. The level of maintenance activity is then to be determined by the life-cycle cost analysis and environmental life-cycle assessment of M&R alternatives. The optimal M&R alternative is the one with the lowest cost combined with minimal environmental impact. Using these methodologies, the SSP structure owners will gain improved capabilities to monitor present-day conditions of SSP infrastructure and prioritize structures that will require sust...

Reliability assessment of structural systems with interval uncertainties under spectrum-compatible seismic excitations

The statistical inference of structural resistance includes not only the analysis to the structural reliability, but also the important contents in assessment of the degree of structural reliability. At present, the analysis to resistance basically belongs to the method of indirect inference, which is influenced by various factors such as computational model, statistical sample, the size of space and so on so as to limit the precise degree of inference results. Proof load method is a method to directly infer structural resistance, while the method of indirect inference has the advantage on theory. In this paper, the information of resistance offered by proof load is adopted directly to make analysis and inference so as to search for the application of proof load in the assessment of structural reliability.

In this paper, the Monte Carlo simulation is applied to reliability assessment of frame structures. Importance sampling technique is used to reduce the sample size that is necessarily large for small failure probability problems, and Neumann expansion method is adopted to decrease the computational effort in finite element analysis. Based on the analyses of numerical results, it is discussed how to select and check importance sampling distributions. Numerical examples show that the Monte Carlo simulation combined with importance sampling and Neumann expansion is much more advantageous than direct Monte Carlo simulation.

Seismic reliability assessment of RC structures including soil–structure interaction using wavelet weighted least squares support vector machine

WS3a1 - Simulation of Probabilistic Fatigue Crack Growth

ABSTRACTEngineering projects and designs are commonly developed in a systems framework that includes different types of uncertainty. In general, uncertainty can be of either the ambiguity or vagueness type. The theory of probability and statistics has been extensively used in engineering to deal with the ambiguity type of uncertainty. The theory of fuzzy sets and systems has been used to model the vagueness type of uncertainty in many engineering applications. In this paper, the role of fuzzy sets in engineering systems is described using a selected example area that deals with vagueness in failure definition as used in solving structural reliability problems. The reliability of a structure is commonly based on an explicit definition of failure, making structural reliability dependent on this definition. The vagueness in the perception of damage and failure introduces another class of uncertainty, in addition to the commonly realized and modeled class of uncertainty, i.e., ambiguity. In this study, a methodology for reliability assessment of structures based on a fuzzy definition of failure is developed. The significance of the contribution is in providing the reliability of the structure over a damage spectrum.

To reduce the runtime and ensure enough computation accuracy, this paper proposes a structural reliability assessment method by the use of sensitivity analysis (SA) and support vector machine (SVM). The sensitivity analysis is firstly applied to assess the effect of random variables on the values of performance function, while the small‐influence variables are rejected as input vectors of SVM. Then, the trained SVM is used to classify the input vectors, which are produced by sampling the residual variables based on their distributions. Finally, the reliability assessment is implemented with the aid of reliability theory. A 10‐bar planar truss is used to validate the feasibility and efficiency of the proposed method, and a performance comparison is made with other existing methods. The results show that the proposed method can largely save the runtime with less reduction of the accuracy; furthermore, the accuracy using the proposed method is the highest among the methods employed.

A study on the effect of flaw detection probability assumptions on risk reduction achieved by non-destructive inspection

The two first order reliability methods (FORM) for computing the non-probabilistic reliability index, namely the mean-value method and the design-point method, are investigated. A performance comparison is presented between these two methods. The results show that: (1) the value of the reliability index of the mean-value method depends on the specific form of the limit state function, whereas the value of the reliability index of the design-point one does not;(2) the design-point method should be preferentially used in structural reliability assessment. The conclusions are verified by a numerical example.

2008S-OS2-8 A Technical Problem with Structural Reliability Assessment