A model for the evaluation of intervention strategies for bridges affected by manifest and latent deterioration processes

Abstract

Markov models are often used in bridge management systems to evaluate intervention strategies (ISs) for bridges affected by manifest deterioration processes (MnDPs). These models do not directly take into consideration the effect of latent deterioration processes (LtDPs) on the object, i.e. the deterioration that might occur due to natural hazards (e.g. earthquakes and floods). In cases where there is a negligible probability of the occurrence of natural hazards, this is justified, otherwise it is not. In this paper, a model is proposed that can be used to evaluate ISs for bridge elements and bridges considering both MnDPs and LtDPs. The model is an extension of the Markov models, and includes condition states (CSs) that can occur due to both MnDPs and LtDPs, as well as the probabilities of transition (p.o.ts) between them. The contributions to the p.o.ts due to MnDPs are initially estimated using well-established methods and adjusted for the contributions to the p.o.ts due to LtDPs, which are estimated using fragility curves and adjusted considering element dependencies, i.e. how the elements of a bridge work together. The use of the model is demonstrated by predicting the future CSs of a bridge affected by both MnDPs and LtDPs.

Keywords::

• Markov models
• infrastructure management
• bridge management
• hazard risks
• optimal intervention strategy
• fragility curves

Notes

^1. Email: [email protected]

^2. Email: [email protected]

^3. Manifest deterioration processes: Processes that result in changes in the condition of an object so that there is sufficient warning so that an intervention can be executed so that there is a negligible probability that an inadequate level of service is provided. An example of a typical MnDP is chloride-induced corrosion of reinforced concrete. MnDPs considered in this paper are limited to those that can be modelled as Markov chain processes.

^4. Latent deterioration processes: Processes whose progression over time is not followed in a way that a condition of the object triggers the execution of an intervention early enough so that it can be assumed that the probability object will provide an unexpected inadequate level of service is negligible. An example of a typical LtDP is ground accelerations due to an earthquake.