ABSTRACT

The present study reports a probabilistic finite element modeling and analysis procedure that is useful for the assessment of structural integrity and reliability. This procedure is efficient, accurate, and simultaneously accounts for the variabilities and uncertainties in the governing parameters as well as the nonlinear nature of the physical failure mechanisms. In the approach, nonlinear finite element methods are employed to model the physical response characteristics while an integrated stochastic finite element formulation that employs a FORM-based adaptive response strategy is used for probability calculations. Uncertainties in loads, material properties and structural properties are considered, and reliability levels for selected stiffened-panel configurations, with reference to some strain-based failure criteria, are determined. Probabilistic sensitivity studies are also conducted to study the importance of the influencing parameters as well as the uncertainty in these parameters. Results are compared to those obtained using approximate analytical models, and it is shown that the simplified models may predict reliability and sensitivity values that have significant errors. Finally, the paper suggests a strategy by which this methodology can be employed to improve the design of stiffened-plated structures.

INTRODUCTION

Stiffened-plated structures have found wide applications in engineering construction. They have constituted the preferred mode of construction for ships, offshore structures as well as aircraft, for example. Thus, the assessment of the structural integrity and the residual strength of these structures require a thorough understanding of the behaviour of the basic structural elements which are essentially the main building blocks for the larger structural system. Traditionally, the assessment of structural integrity has been carried out via the application of simplified analytical models that are defined for various modes of failure for the stiffened panel configurations. Later on, sophisticated analytical techniques such as the finite element method were introduced to permit more realistic assessments of structural integrity.

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