This study investigates damage detection in the tendons of post-tensioned segmental box girder bridges, focusing on the vibration-based technique and its application in conjunction with the Precursor Transformation Matrix (PTM). Due to the critical role of bridge tendons in structural integrity, efficient and timely detection methods are essential. The methodology combines theoretical modeling with Finite Element Method (FEM) simulations and empirical data collection to evaluate the PTM’s effectiveness in identifying tendon damage. Key results indicate that the PTM, when paired with vibration analysis, enhances the identification and localization of damage, proving to be a robust method in structural health monitoring. This approach not only speeds up damage detection but also potentially lowers maintenance costs by pinpointing specific damage sites, thereby preventing widespread structural failures. The findings offer a promising tool for ensuring the longevity and safety of post-tensioned bridges.

Skewed supports complicate load paths in continuous steel I-girder bridges, causing secondary stresses and differential deformations. For a continuous bridge where tensile stresses are developed in the top flange of the steel girders over the intermediate supports, these effects may exacerbate potential fatigue issues for the top flanges. There is a gap in knowledge regarding the level of stress one can expect at these locations, and the stress level can render the problem either serious or trivial. This paper has been successful in providing this information, which was not available before. The study examines the fatigue performance of the top flange in girders over skewed supports. Results are presented from a detailed investigation consisting of 3D finite element modeling to evaluate 26 skewed bridges in the State of Florida that represent the wide range of geometries found in practice. The analysis focused on stress ranges in the top flanges and axial demands on end cross-frame members under fatigue truck loading. A preliminary analysis helped to select the appropriate element type and support conditions. The maximum factored stress range of 3.63 ksi obtained for the selected group of bridges remains below the 10 ksi fatigue threshold for an AASHTO Category C connection, alleviating the concerns about the fatigue performance of the continuous girder top flange over the intermediate pier. Hence, fatigue is unlikely to be a concern in the flanges at this location. Statistics on computed stress ranges and cross-frame forces that provide an understanding of the expected values and guidance for detailing practices are also presented. A limited comparative refined FE analysis on two different types of end cross-frame to girder connections also provided useful insight into the fatigue sensitivities of the skew connections. Half-Round Bearing Stiffener (HRBS) connections performed better than the customary bent plate connections. The HRBS connection reduces girder flange stress concentration range by at least 18% compared to the bent plate connection. The maximum stress concentration range in bent plate components is significantly higher than in the HRBS connection components. The work documented in this paper is important for understanding the fatigue performance of the cross-frames and girders in support regions in the upcoming 10th edition of the AASHTO Bridge Design Specifications that may include plate stiffeners oriented either normally or skewed to the girder web, or Half-Round Bearing Stiffeners.

The state-of-the-art literature in engineering provides information on the current state of technical subjects, shapes the understanding of relevant research, and communicates potential next directions for future exploration in relation with condition and risk assessment and sustainable maintenance of post-tensioned (PT) concrete bridges. However, the formulation of a quantitative methodological framework in selecting suitable safety assessment and management techniques for in-service PT concrete bridges is insufficient in the current literature. The absence of such a framework could render ineffective the sustainability of bridge maintenance strategies. In addition, the failure of structural assets due to deterioration and lack of proper maintenance is regarded as an important risk aspect. This is because structural failure often results in adverse economic, environmental, and safety outcomes. To underscore this, formulating mitigation strategies through sustainable asset maintenance programs is consequential. In recognition of the current limitation, this paper proposes a new framework with a structured methodology for the risk assessment and management of PT concrete bridges. This framework helps the bridge practitioners to navigate through design, inspection results, environmental factors, estimation of probability of failure, and corresponding consequences to calculate the risk and decide on the maintenance. It encompasses the decision on the type and interval of the inspection regime, repair and strengthening, and potentially replacing existing work. The presentation of this framework is original in that it carries the stochastic approach through all steps of risk assessment and maintenance decision making while allowing room for the inclusion of evolving methods. The proposed framework can be used for the development of a complete guide capable of stochastic, reliability-based, data-driven, and quantitative risk assessment and maintenance management for PT concrete bridges.