Accerelated Pavement Testing Group (APTG)
(Former SWAG)
The SWAG studies the potential of utilizing stress waves to obtain structural information on constructed civil infrastructures, such as pavements and piles. Nondestructive stress wave testing is performed on various civil structures in service. The data acquisition and signal analysis are performed using the computer program SWAP (Stress Wave Analysis Program) developed by the SWAG. This program has a graphic user interface and is capable of performing Fast Fourier Transform, Fourier Phase Method, and Short Kernel Method. The Short Kernel Method (SKM) is a frequency dependent scanning algorithm based upon the cross-correlation procedure and amplifies a given frequency within the time domain of a signal for more accurate determination of phase velocity for the frequency.
The SWAG also develops numerical solutions for structural systems which can be used to developing a database composed of system properties (e.g., modulus, damage state, etc.) and system responses (e.g., phase velocities). Artificial neural network (ANN) and other system identification techniques are then employed to develop the relationships between system properties and system responses. Currently, the SWAG is developing condition assessment procedures for installed timber piles and asphalt pavements using dispersion analysis of bending waves and surface waves, respectively.
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