Experimental Time Domain Reflectometry (TDR) data obtained from the field are compared with numerical simulations using a finite-difference solution of the transmission line equations. The model simulates transmission of a voltage pulse along a lossy coaxial cable where deformities on the cable, such as crimps and shears, are represented by...
Cosmetic cracks are very common in structures, and most of the time they remain unnoticed and do not decrease the structural integrity. Although these cracks are unremarkable and barely noticeable, occupants become concerned about these cracks when construction occurs nearby. In order to investigate the true nature of these cracks,...
The gradual evolution of the material properties of a cement-based material, i.e. the stiffness of cement paste, is the result of the continuous change of the microstructure with the progress of the hydration process. Based on an existing micromechanical model for the simulation of the shear and elastic modulus of...
This presentation contains information on the keynote paper "Health Monitoring of Early Age Concrete". The presentation was delivered by Surendra P. Shah at CONSEC'04 in Seoul, Korea on June 30, 2004.
Time Domain Reflectometry (TDR) is a versatile technology amenable to a variety of measurements and nondestructive monitoring of infrastructure conditions. It can be utilized to monitor deformation of soil/rock and structures, monitor changes in fluid levels, and monitor water content of soils. Furthermore, this monitoring can be automated using systems...
Two longwall coalmine panels were mined at a depth of approximately 156 m (510 ft) beneath I-70 east of Washington, Pennsylvania such that it crossed the width of one panel at two locations. The Pennsylvania Department of Transportation (PennDoT) assumed responsibility for real time monitoring of both ground deformation and...
Miniaturized, wireless instrumentation is now a reality and this thesis describes development of such a system to monitor crack response. Comparison of environmental (long-term) and blast-induced (dynamic) crack width changes in residential structures has lead to a new approach to monitoring and controlling construction vibrations. In wireless systems transducer power...
The thesis describes the second phase of development of the Autonomous Crack Comparometer (ACC) system to incorporate measurements of ground motions and add several changes in the autonomous operation. In order to obtain the ground motion and air blast data, four additional transducers have been added. There are now a...
This thesis consists of the data and analysis of structural responses for two different studies: the Office of Surface Mining (OSM) study of the velocity response of “atypical” residential structures and the Autonomous Crack Monitoring (ACM) study. The main basis of this thesis was to do additional analysis on a...