Characterization and implementation of distributed coaxial cable crack sensors for embedment in reinforced concrete structural members

Earthquakes pose a major problem to the functionality of our society as whole. One of the reasons for that is the extensive damage that can occur to the load-carrying components of a structure during an earthquake. Bridges, parking structures, office buildings, and dwellings often need to be inspected before normal use can continue. A new tool for aiding in the inspection and damage detection process is discussed in this thesis. This new tool is a distributed crack sensor that can be embedded in reinforced concrete structural components. Previous work has been done concerning the characterization of the sensors by Huimin Mu at the University of Missouri--Rolla under Dr. Genda Chen. The main focus of this thesis is to develop a better understanding of how these sensors perform in a number of applications. During testing of the sensors under dynamic loading, it was discovered that the sensors possess an ability to record the crack history of the member into which they are embedded. This feature has become one of the main topics of study for this thesis. Tests were performed in an attempt to quantify the characteristics that cause this effective “memory” to occur. It has been found that the sensors also perform well when installed into a member that is retrofitted in a manner that prohibits the discovery of cracks by visual inspection. This study also addresses the tested sensitivity of the sensors in various laboratory applications on large-scale beams and columns and the ability of the sensors to withstand multiple cycles of testing as well as field applications of testing --Abstract, page iii