Bayesian networks for system reliability reassessment Sankaran Mahadevan*, Ruoxue Zhang, Natasha Smith Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, Tennessee, 37235, USA Accepted 7 September 2001 Abstract This paper proposes a methodology to apply Bayesian networks to structural system reliability reassess- ment, with the incorporation of two important features of large structures: (1) multiple failure sequences, and (2) correlations between component-level limit states. The proposed method is validated by analytical comparison with the traditional reliability analysis methods for series and parallel systems. The Bayesian network approach is combined with the branch-and-bound method to improve its efficiency and to facilitate its application to large structures. A framed structure with multiple potential locations of plastic hinges and multiple failure sequences is analyzed to illustrate the proposed method. # 2001 Published by Elsevier Science Ltd. All rights reserved. Keywords: Bayesian network; Reliability reassessment; System reliability; Failure sequence 1. Introduction Reliability-based design and in-service inspection (or development testing) are two com- plementary approaches for ensuring the safe performance of structures. Physics-based computa- tional reliabilitymethodsaremuchmorecost-efficientforlargeandcomplexstructures,andaretools that could be used when experimental data are difficult to obtain. However, due to the approxima- tionsinthecomputationalmodelandthelimitedstatisticaldataontheinputvariables, there may be uncertainty or error in this computation. Therefore, when inspection/test information is available, the results of the two approaches should be combined for a robust re-estimation of the structural reliability. Bayes’ theorem, which is used for probabilistic updating, provides an appropriate frame- work for this purpose. Several important studies have been reported to incorporate the information from inspection for fatigue reliability reassessment using Bayes’ theorem [1–4]. All these studies are based on component level reliability analysis and individual limit states. 0167-4730/01/$ - see front matter # 2001 Published by Elsevier Science Ltd. All rights reserved. PII: S0167-4730(01)00017-0 Structural Safety 23 (2001) 231–251 www.elsevier.com/locate/strusafe * Corresponding author. Tel.: +1-615-322-3040; fax; +1-615-322-3365. E-mail address: sankaran.mahadevan@vanderbilt.edu (S. Mahadevan).