Development of rapid assessment tools for structural members using ultrasonic stress wave techniques

Chen, Andrew
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University of Delaware
The requirements for inspecting a structure depend on a variety of factors, including: routine inspections, change in operating conditions, rehabilitation, accidents and after extreme events. Although visual inspections are generally adequate for maintaining the safety of most structures, if quantitative information is required, then non-destructive testing (NDT) techniques are needed. Methods of rapidly estimating in-situ stresses and characterizing flaws in structures are both highly desirable for supplementing visual inspections. Currently, there is no existing NDT method for determining in-situ stresses in a concrete member. Additionally, established methods of characterizing flaws in steel members are generally time consuming and most do not allow for remote monitoring. The objective of this research is twofold: to test the viability of using (1) polarized ultrasonic shear waves to estimate in-situ stresses in concrete members and (2) analysis of diffuse ultrasonic wave fields for detecting and characterizing flaws in a steel member. This thesis establishes basic research for these two subjects and covers the fundamental observations derived from experimental testing, signal and data processing. The results demonstrate that the two approaches could potentially be used in an integrated method for monitoring changes in the integrity of structural members remotely.