Doctoral Defense by Giao Vu

On Friday, 14 August 2026, at 2:00 PM Giao Vu holds her PhD defense, titled 'A Virtual Coda Wave Interferometry Laboratory for Damage Assessment in Reinforced Concrete Structures'.

Abstract:
Concrete infrastructure ages long before it fails visibly. Detecting that deterioration early – while repairs are still cheap – is one of the central challenges in structural health monitoring. Coda Wave Interferometry (CWI) offers a promising solution by exploiting the late-arriving portion of ultrasonic measurements. Having travelled repeatedly through the material, these waves sample a far larger volume than conventional methods and are sensitive to microstructural change. Embedded ultrasonic sensors are inexpensive, making CWI an attractive basis for permanent monitoring systems. The obstacle is interpretation: a measured signal change tells us that something has happened inside the concrete, but not what, where, or how severe.

This thesis closes that gap with a virtual CWI laboratory. Meso-scale models simulate the cracking process and the ultrasonic waves travelling through it, linking a structure‘s internal state directly to its measured response. The framework was validated against real experiments from material specimens up to reinforced concrete beams, across varying mixtures, structural layouts, and sensor configurations.

The result is a quantitative map from velocity change to what engineers care about: crack width, reinforcement strain, stiffness degradation. The synthetic data then trained a transformer-based classifier which, after domain adaptation, predict damage states from real measurements with good accuracy.

Together, the framework provides scalable tool for designing sensor networks, generating validated training data, and translating monitoring signals into decisions.

Promotionsaushang_GiaoVu.pdf