A. Zanaz1, S. Yotte2, F. Fouchal2, and A. Chateauneuf3
1)  Military Center of Engineering and Infrastructure Development
Hussein Day, Algiers, Algeria
2)  Laboratory of Heterogeneous Material Research Group, Civil Engineering and Durability Team
Boulevard Jacques Derche, 19300, Egletons, France
{sylvie.yotte, fazia.fouchal}@unilim.fr
3)  Clermont University, Blaise Pascal University, Institute Pascal
BP 10448, F-63000 Clermont-Ferrand, France

Keywords: Reliability, Variability, Alteration, Masonry, Vault, Bridge, Bayesian updating.

Abstract. The present paper deals with the case of generalized alteration of masonry vault bridges (stones and joints) to develop a reliability-based approach for masonry bridge management. The alteration is modeled as a Young’s modulus variability throughout the segments of the vault. The results have highlighted the influence of the Young’s modulus variability of the segments on the vault bearing capacity. At the date of construction of the structure, this natural variability is not problematic but can become so. Indeed, the Young’s modulus variability is increased over time, due to environmental and loading conditions. It is a very discrete form of pathology that can be completely invisible, making it dangerous. The objective of this study is to evaluate the influence of this change in Young’s modulus variability on the instantaneous
and time-dependent reliability of the masonry vault, and to present a model for predicting its performance over time.
The proposed methodology is applied to simulate five situations. The first two situations consist in determining the evolution of the probability of failure along the lifetime of the structure with and without taking into account the traffic history. The third situation takes into account the new measurements that have become available following an inspection using Bayesian updating. The last two cases consider a temporary and a permanent increase in traffic respectively. The updating of the probability of failure make it possible to estimate, according to the duration of traffic increase, the time the manager of the structure has to make the necessary arrangements in order to reduce the probability of failure. This methodology also makes it possible to evaluate the maximum duration of the traffic increase and the impact of any accused delay, either in relation to the start date of the traffic increase, or to its duration.