THESIS
2017
xxi, 166 pages : illustrations ; 30 cm
Abstract
Considering the limitations of the current structure health monitoring techniques, a novel
low-cost capacitive transducer (CT) using capacitance signals, which has the potential to
provide accurate health assessment and damage prediction for reinforcement concrete
structures, is firstly developed in this study. Four major works including the development of
the capacitive sensor, the optimization work of CT sensor design, the application of the CT in
rebar size/depth/position and rebar corrosion tests using the developed CT are mainly
introduced. In the sensor development process, two designs of capacitive transducers are
discussed for condition assessment of rebar and concrete, respectively. In order to verify the
effectiveness of the designed capacitive sensor, five preliminary...[
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Considering the limitations of the current structure health monitoring techniques, a novel
low-cost capacitive transducer (CT) using capacitance signals, which has the potential to
provide accurate health assessment and damage prediction for reinforcement concrete
structures, is firstly developed in this study. Four major works including the development of
the capacitive sensor, the optimization work of CT sensor design, the application of the CT in
rebar size/depth/position and rebar corrosion tests using the developed CT are mainly
introduced. In the sensor development process, two designs of capacitive transducers are
discussed for condition assessment of rebar and concrete, respectively. In order to verify the
effectiveness of the designed capacitive sensor, five preliminary experiments are conducted
and the experiments results also showed that CT signals could be applied to predict rebar
positions inside the concrete. Finally, FEM simulations were implemented for the last
experiment, and comparison results have well verified the effectiveness of the developed
capacitive sensor. In the sensor optimization work, performances of different parameters in
terms of electrodes size/shape, concrete length, electrodes spacing and rebar size are
compared in order to get an optimized sensitivity in the rebar depth testing. In the rebar
size/depth/position test, both numerical simulations and experiments have been carried out to
verify the effectiveness of the developed capacitive sensor. Results have shown that the
developed CT with innovative capacitance measuring method has great accuracy in
predicting the rebar size and position, which is the foundation of the reinforcement corrosion
detection. In the corrosion testing part, a novel corrosion development model according to the
increase of rust layer thickness is firstly proposed and direct quantitative relationship
between the capacitance outputs and the rust layer thickness is built to measure the corrosion
degree. Apart from uniform corrosion testing, localized corrosion testing including half-rebar
corrosion, side corrosion and various banding layer corrosion have been implemented to
verify the function of the CT technique. It can be concluded that the developed capacitive
transducer is applicable in the condition tests of reinforced concrete structures and it paves
the way for quantitatively evaluate the corrosion degree of the reinforced rebar.
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