Finite element-based reliability assessment of quay walls

ABSTRACT

While reliability methods have already been widely adopted in civil engineering, the efficiency and robustness of finite element-based reliability assessments of quay walls are still fairly low. In this paper, the reliability indices of structural and geotechnical failure modes of two real-life quay walls are determined by coupling probabilistic methods with finite element models, taking into account a large number of stochastic variables. The reliability indices found are within the range of the targets suggested in the design codes presently in use. Nevertheless, neglecting model uncertainty and correlations between stochastic variables leads to an underestimation of the probability of failure. In addition, low sensitivity factors are found for time-independent variables, such as material properties and model uncertainty. Furthermore, the results are used to reflect on the partial factors used in the original design. Important variables, such as the angle of internal friction, are subjected to a sensitivity analysis in order to illuminate their influence on the reliability index. Port authorities and terminal operators might be able to use the findings of this paper to derive more insight into the reliability of their structures and to optimise their service life and functionality, for example by deepening berths or increasing operational loads.

KEYWORDS:

• Quay wall
• reliability
• finite elements
• partial factors

Acknowledgements

On behalf of Delft University of Technology, Deltares, Plaxis, TNO and the Port of Rotterdam Authority, the authors would like to thank all the companies and organisations involved in this study – and SmartPort in particular – for their support, funding and hospitality. Special thanks go to Mr H. Brassinga, who reviewed the finite element models used. Prof. A. C. W. M. Vrouwenvelder, Dr J. G. de Gijt and Mr A. van Seters are gratefully acknowledged for sharing their knowledge and for reviewing the methods used to determine partial factors of safety on behalf of TNO, Delft University of Technology and Fugro respectively. The support and review of Dr R. Lebrun of the OpenTURNS community was of great help during our interpretation of the Abdo-Rackwitz algorithm. Finally, Ms A. Laera and Mr. M. van der Sloot of the Plaxis company are gratefully acknowledged for their contribution to the development of the ProbAna^® reliability interface.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

On behalf of Delft University of Technology, Deltares, Plaxis, TNO and the Port of Rotterdam Authority, the authors would like to thank all the companies and organisations involved in this study – and SmartPort in particular – for their support, funding and hospitality.