High-strength concrete beams reinforced with prestressed prisms and instrumented with fiber optic sensors.

摘要

The research achievements presented in this dissertation address the evaluation of a new composite construction concept and the development of advanced Fiber Optic Sensor technologies for monitoring of Civil Engineering structures.;A comprehensive testing program was designed and carried out in three phases. Phase I covered the development of a fiber optic intensity-modulated microbend sensor and the evaluation of sensor performance in the direct tension tests and small scale structural concrete element bending tests.;Phase II covered the investigation of Fiber Optic Bragg Grating (FOBG) sensors for direct strain measurement in structural components. The strain optic effect of the FOBG sensors was theoretically evaluated and followed by a precise experimental calibration procedure. A successful package of the FOBG sensor was used and modeled. Good bonding of sensor to the structure was shown to be imperative for the maximum transfer of load induced-strain. Strain measurement obtained from both embedded and exposed FOBG sensors showed excellent correlations with those obtained from electric strain gages.;Phase III included the experimental and theoretical investigations to identify the major parameters which affected the structural behavior of concrete beams with prestressed prisms as main tension reinforcement. Seventeen high strength concrete (with ;The distinct characteristic of this type of composite construction is that only the prisms are subjected to the prestressing forces. Thus a high level of precompression can be achieved in those prisms due to their smaller cross-sectional areas compared to the overall cross-section of the situ-cast concrete beams. This concept permits, therefore, creating a crack-free zone under service load or at overload conditions, thereby providing adequate protection against corrosion to the prism strands and a potential improvement of the flexural rigidity of the main reinforced concrete element, with consequent reduction in deflection and crack width at working loads.