Date of Award

Summer 2022

Document Type

Thesis - Open Access

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

Committee Chair

Dr. Jeff Brown

Committee Advisor

Dr. Jeff Brown

First Committee Member

Dr. Siddharth Parida

Second Committee Member

Dr. Dan Su

Abstract

Non-destructive evaluation of post-tensioned structures with flexible fillers is desperately needed due to their rapid implementation in the State of Florida, primarily in roadway structures. This study provides an overview of existing evaluation methods for traditional post-tensioned structures with cementitious grouts and further explores two promising methods to be applied to flexible filler systems. The first method, diffuse ultrasound spectroscopy, indirectly evaluates posttensioned structures by quantifying the severity of microcracking in the structure. Microcrack detection is accomplished by processing received waveforms generated with a pitch-catch transducer configuration. The second method, coda-wave interferometry, measures the velocity variation at the tail end of waveforms, known as the coda, between varying stress states of a structure. The velocity variation can be correlated to cracking events, structural yielding, and stress level changes. First, preliminary testing was done for both methods to find the optimal test setup and validate the methods' efficacy. Algorithms were developed for both promising methods using the preliminary testing data for development. Next, the methods underwent experimental testing composed of direct compression and 3-point load testing on normally reinforced and posttensioned small-scale beams. The experiments show the methods' effectiveness in indirectly evaluating the health of the post-tensioning system with flexible fillers. Overall, the two methods prove to be very promising and are recommended to be explored in further studies.

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