Abstract
Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This article describes development and testing of system based on fiber Bragg grating (FBG) sensors that can detect changes in strain and temperature. The first phase of the research has been focused on the development of new fiber optic sensors for the monitoring of concrete structures and their investigation in laboratory conditions. The work also shows novel applicability of the same FBG technology for glulam structures. Mechanical loading tests of the concrete beam as well as glulam beam with embedded sensors were carried out. Data measured by developed fiber optic sensors were compared with the readings from reference sensors as well as with the analytically calculated values. The achieved results proved good agreement between the measured data, analytical data and reference methods. In second phase of the research, the pilot installation of the sensors was carried out on the newly constructed prestressed-concrete bridge. The bridge was monitored throughout pre-stressing phase and monitoring continued after the completion of the construction works. Problems with the fragility of the sensors occurred during the measurements, but the obtained results provide a good basis for further improvement of the system.
Highlights
As far as public safety is concerned, the long-term structural health monitoring (SHM) of infrastructure, such as bridges or tunnels or, considering public buildings, roof structures, plays a crucial role
Three different types of fiber optic sensor were integrated into structure of monolithic reinforced concrete test beam: the tested different types of fiber optic sensor were integrated into structure of monolithic reinforced concrete embedded sensor, the tested 3D printed sensor and the reference HBM strain sensor, see Figure 1a
This chapter describes and analyzes the results obtained from laboratory testing of concrete specimen and field measurements of the bridge structure
Summary
As far as public safety is concerned, the long-term structural health monitoring (SHM) of infrastructure, such as bridges or tunnels or, considering public buildings, roof structures, plays a crucial role. Well provided SHM is able to detect the progress of more or less serious damage and warn of extreme negative situations (oncoming collapse of the structure). The designer of load-bearing structure has several options of the SHM system design. This article describes an embedded system based on fiber Bragg grating (FBG) sensors, which is able to detect changes in strain and temperature. FBG sensor is based on a periodic variation in the refractive index of the fiber core (Bragg grating), which reflects particular wavelengths of light in a form of narrow Gaussian peaks, while the rest is transmitted. The Bragg grating frequency and refractive index are sensitive to changes in strain and temperature. The principles of FBG sensing are described in more detail, for example, in [1,2,3]
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