Non-destructive testing strategies for post-tensioned bridges: a framework for selecting investigation methods

Post-tensioned reinforced concrete bridges are inherently vulnerable structures, primarily due to the hidden and complex configuration of their internal tendons, which makes deterioration difficult to detect through conventional inspection or visual assessment methods. However, the evaluation of existing bridges cannot follow a one-size-fits-all approach. The assessment process is inherently complex, shaped by the unique features and specific vulnerabilities of each structural typology. Among these, post-tensioned (PT) concrete bridges have drawn particular attention from the scientific community in recent years due to their pronounced susceptibility to hidden tendon corrosion, which has led to notable failures. For such structures, an accurate measure of structural reliability must consider the probability of failure as influenced by ongoing material deterioration and evolving traffic demands. This forms the foundation of a risk-based decision-making approach to guide maintenance planning and intervention strategies, aligned with available financial resources. In this context, the paper presents a structured and practical evaluation framework that ranks these techniques based on four essential criteria: measurement accuracy, ease of implementation, cost-effectiveness, and the level of disruption to bridge operations. The goal is to provide bridge owners and managers with a reliable tool to support the selection of the most appropriate ND method for detecting specific defects. To demonstrate the applicability and relevance of the proposed methodology, a case study bridge is presented, simulating different working scenarios. This practical example validates the framework and highlights its potential in real-world decision-making contexts.