A grid-based stress-field imaging method for concrete structures using directional acoustoelastic measurements.

Area of Science:

• Civil Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Accurate assessment of internal stress fields is vital for concrete structure integrity.
• Existing methods for stress monitoring in concrete have limitations in spatial resolution and accuracy.

Purpose of the Study:

• To develop and validate a novel two-stage inversion framework for stress-field imaging in concrete structures.
• To recover local stress information and directional evolution from long-path ultrasonic measurements.

Main Methods:

• Integration of acoustoelastic theory with a grid-based time-variation decomposition strategy.
• Two-stage inversion: first principal stress direction field determination using RBF interpolation, followed by in-plane stress reconstruction.
• Utilized directional acoustoelastic measurements along multiple non-collinear sensing paths.

Main Results:

• Successfully reconstructed the principal stress direction field and in-plane stresses in a reinforced concrete corbel column.
• Demonstrated good agreement with finite element analysis results for both stress direction (curl RMSE of 0.01337) and magnitude (absolute error of 0.05 MPa).
• Showed improved inversion accuracy when stress-induced time variations dominate over concrete heterogeneity.

Conclusions:

• The proposed stress-field imaging method is feasible and reliable for characterizing internal stress fields in concrete.
• The framework enables both qualitative and quantitative assessment of stress distribution and evolution.
• This technique offers a promising approach for structural health monitoring and damage assessment in concrete structures.