The nondestructive evaluation (NDE) research community focuses primarily on the identification and characterization of local material-level degradation and damage. Structural health monitoring (SHM) researchers aim to provide global structural assessments associated with load paths, load carrying capacities, and more. Although both approaches clearly are complementary in nature, these research communities are mostly independent and interact little. This workshop brings these groups together to promote and identify opportunities for the integration of NDE and SHM.
Whether one examines the view of infrastructure presented by the ASCE Infrastructure Report Card, or the Grand Challenge statements put forth by the National Academies and the National Science Foundation, it is clear that more sustainable approaches for both the preservation and renewal of civil infrastructures are needed. A key element to achieving this vision includes assessment strategies that better quantify risks, diagnose performance problem, and inform decisions related to infrastructure interventions. Over the last decade this recognition has spurred significant interest in the fields of nondestructive evaluation (NDE) and structural health monitoring (SHM). Although much progress has been made, these approaches have remained largely isolated from one another. The objective of this presentation is to put forth an integration framework (adapted from Structural Identification) to leverage the inherently complementary aspects of the local and global perspectives provided by NDE and SHM. In addition to the discussion of the framework, this presentation will also discuss several case studies to illustrate both the benefits and challenges associated with achieving this integration.
Although the underlying phenomena and data analysis schemes of most nondestructive evaluation (NDE) and structural health monitoring (SHM) technologies are very similar and in some cases identical, these two families of test methods are often perceived to be different. As a result, the two families of methods are applied separately and the two research communities operate in isolation of each other. However if the notable similarities between the two families of test methods are exploited and they are applied together in a symbiotic fashion, it is likely that more complete understanding of structural health is obtained. For example, a combination of these family of methods can provide both local and global information, across short and longtime scales. Bridging the gap between NDT and SHM thus can provide better more comprehensive infrastructure health monitoring, so it should be encouraged.
Ultrasonic echo methods are are used for many purposes, e.g. imaging the geometry of constructions, locating internal features as rebar, tendon ducts or voids, and estimating material parameters. The most used imaging method used to reconstruct the true positions of reflectors is SAFT (Synthetic Aperture Focusing Technique) which is fast and reliable for point-like or flat near-horizontal geometries. For more complex objects, geophysical techniques have been proposed recently, which are able to map vertical boundaries or to look behind objects. Ultrasonic measurements can be use for monitoring as well. Especially when embedded transducers are used in combination with very sensible feature extraction algorithms as coda wave interferometry, subtle changes of stress or material condition can be detected. The presentation describes several emerging techniques, that will extend the current capabilities of ultrasonic methods significantly. Experimental results are shown to support this statement.
In this presentation, a framework of bridge preservation with integrated visual inspection, sensing, nondestructive evaluation and robotic technologies is proposed with focused discussion and illustrations on a new ‘lab-on-sensor’ concept for the quantification of structural behaviors. Although subjective, rapid visual inspections of all bridges in a transportation network are first carried out with a quick walk through, and in-depth inspection of some targeted bridges is then performed with nondestructive evaluation tools installed on a robotic platform for mainly qualitative assessment. Representative bridges and critical elements are next monitored for quantitative assessment of structural behaviors. Finally, confirmation visual inspection on the bridges with abnormal behavior is conducted as needed for condition assessment and load rating. Once confirmed, maintenance prioritization of deficient bridges is developed and the local deficiencies identified can be remediated by using a robotic arm installed on a unmanned aerieal vehicle.