Evaluation Of Concrete Bridges Research Articles

Defect-Based Condition Assessment of Concrete Bridges

Reliable bridge condition assessment is considered the first step, and perhaps one of the most essential elements, of an efficient bridge management system. This consideration stems from the fact that available assessment inputs are constantly interpreted for maintenance decisions and budget allocation to the deserving, intervention-needy bridges within a region's inventory. Thus, carrying out effective bridge assessment is vital to ensure the safety and sustainability of the bridge infrastructure. In practice, the evaluation of concrete bridges is mostly conducted on the basis of visual inspection, associated with considerable uncertainty and subjectivity inherent in human judgments. Additionally, conclusions are often drawn in the absence of a thorough review of critical factors. Therefore, to circumvent the existing limitations, this study proposes a fuzzy hierarchical evidential reasoning approach for detailed condition assessment of concrete bridges under uncertainty. The essence of this framework addresses the treatment and aggregation of detected bridge defect measurements systematically to establish an enhanced platform for reliable bridge assessment. The proposed approach is facilitated by a hierarchy structure that models the several levels of a concrete bridge under assessment: bridge components, structural elements, and, most particularly, the measured defects. A belief structure is employed to grasp probabilistic uncertainty (ignorance) in the assessment, while fuzzy uncertainty (subjectivity) is processed through a set of collectively exhaustive fuzzy linguistic variables. Eventually, the Dempster–Shafer theory is used within the suggested framework for accumulating supporting pieces of evidence toward a comprehensive and educated overall condition assessment.

Health monitoring of concrete bridges and vehicle loads correlation analysis based on acoustic emission

In recent years, with the development of digital acoustic emission (AE) systems and the improvement of signal processing technique, acoustic emission technology has been more and more widely used in the research of dynamic processes of compression, tension, impact, fatigue, crack, and fracture of materials and structures. Since correlation analysis of vehicle loads during the monitoring period is lacking in previous concrete bridge structure health monitoring with AE, it is hard to identify the form of AE signals when vehicles cross the bridge. This paper is the first study to combine acoustic emission technique with dynamic monitoring of vehicle loads in bridge structure health monitoring. It studies the feasibility of applying AE technique to existing concrete bridges and discusses characteristic forms of acoustic emission when vehicles pass the bridge. The monitored bridge is a typical highway concrete bridge with small box girders. AE sensors were located on the web, deck plate, and bottom plate of the box girders; a weigh-in-motion system (WIM system) was located in the pavement of bridgehead. The clocks of the two systems were synchronized in order to coordinate the relationship between AE and the weight and velocity of vehicles when they pass the bridge. Based on the analysis of recorded data in 24 hours, the forms of AE signals and the influencing factors were studied; the response characteristics of AE in different locations of the box girder were detected. Then, the correlation between vehicles' dynamic loads and AE features was studied. Reference datum of healthy concrete bridges under the vehicle loads was established, which laid the foundation for further monitoring and evaluation of concrete bridges by AE.

Evaluation of concrete bridges by impact-echo : Ghorbanpoor, A.; Virmani, Y.P.; Fatemi, G.R. Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13–15 Apr. 1992, pp. 82–93. Edited by F. Ansari and S. Sture. ASCE (1992)

Strength of post-tensioned bridge structural members primarily depends on the tensile capacity of their post-tensioning steel reinforcement. To prevent corrosion, the post-tensioning steel is normally encased in plastic or galvanized metal ducts filled with a grout mix. However, corrosion of the steel can result if the ducts are not filled completely. In addition, use of an improper grout mix may result in partial filling of the ducts and/or grout bleeding, which is the separation of water from the cement paste. When bleeding of the grout takes places, the bleed water is usually absorbed back into the hardened grout and a bleed void, sometimes as long as the entire length of the duct, is left in the duct. The bleed voids could be a major factor in the corrosion of post-tensioning steel by facilitating penetration and movement of salt water and other harmful solutions inside of the ducts from the end anchorage areas or cracks, or other flaws, in the surrounding concrete. This study has examined the application of and further development of a non-destructive evaluation technique, the Impact-Echo, for determination of location and extent of voids in the ducts of post-tensioned bridge structural members. Theoretical, laboratory, and field studies have been performed and it has been demonstrated that it is possible to detect, with high reliability, the location and extent of voids in the post-tensioning ducts of concrete structures. It was found that information corresponding to the location of voids within concrete members may readily be obtained by examining the wave reflection frequency values, from an induced impact at the surface of the member, due to the incidents at the free boundaries of these voids.

Evaluation of concrete bridges by impact-echo : Ghorbanpoor, A.; Virmani, Y.P.; Fatemi, G.R. Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13–15 Apr. 1992, pp. 82–93. Edited by F. Ansari and S. Sture. ASCE (1992)

Evaluation of concrete bridges by impact-echo : Ghorbanpoor, A.; Virmani, Y.P.; Fatemi, G.R. Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13–15 Apr. 1992, pp. 82–93. Edited by F. Ansari and S. Sture. ASCE (1992)

System for Strength Evaluation of Concrete Bridges*

System for Strength Evaluation of Concrete Bridges*