Optimization of stress wave-based nondestructive methods in identifying deterioration in concrete structures
The transportation infrastructure across the United States is deteriorating and requires periodic inspection to predict the cost of repair and extent of maintenance activities, to remedy structural problems, and to ensure safety and serviceability. The use of nondestructive testing (NDT) methods in detecting and characterizing flaws in the infrastructure has become more common. Among different NDT methods, the stress wave-based methods, including ultrasonic surface waves (USW) and impact echo (IE) methods, are widely used to maintain concrete structures. In this dissertation, a complete literature review of seismic wave theory and wave propagation in plate like structures, and stress wave-based methods used for concrete infrastructures evaluation is provided. In addition, several finite element models of intact and defective concrete specimens have been developed to simulate the USW and IE methods. Detailed sensitivity and parametric analyses have been performed to identify the sensitive parameters and quantify the limitation of the seismic methods. The numerical data have been calibrated with the experimental data on constructed concrete slabs for the second Strategic Highway Research Program (SHRP2) Projects R06A and R06G. This is the first known instance that the numerical results are calibrated with substantial amount of field data. By relating the numerical and real field data for the IE and USW methods, the outcome of this study has the potential to discriminate between different types of defects and to refine estimating the location and size of defects from information obtained from seismic tests. Finally, an optimum testing set-up to estimate slab thickness and detect different types of defects are recommended. The outcome of this research study is useful for researchers and practitioners in transportation infrastructure agencies to discriminate between different types of defects, to estimate the location and size of the defects from information obtained from stress wave-based methods, and to make decision on existing transportation infrastructures.^
Azari, Hoda, "Optimization of stress wave-based nondestructive methods in identifying deterioration in concrete structures" (2013). ETD Collection for University of Texas, El Paso. AAI3565893.