The utilization of fiber Bragg grating sensors to monitor high performance concrete at elevated temperature

Abstract

Embedded optical fiber Bragg grating (FBG) sensors are used to evaluate the properties of high performance concrete (HPC), subjected to high thermal strain. HPC is composed of polypropylene fibers and steel fibers, as additives, in a cylindrical concrete filled steel tube (CFT). A good agreement response between the FBG temperature sensor and a thermocouple was obtained. In addition, experimental results indicate that a CFT behaves differently from unconfined concrete in the center of a specimen, at a furnace temperature of 250 • C and that polypropylene fibers potentially have a higher capability to restrain spalling than do steel fibers.

Fibre optic sensing of ageing railway infrastructure enhanced with statistical shape analysis

“…A common method is to have a loose bare fibre in an enclosure (tube), which can expand thermally without any influence of external constraints. This is appropriate when sensors are embedded into concrete structures (see for instance [26] and references reported therein). Another method is to have the FBG bonded with a uniform solid, usually metal, which expands thermally and transfers the resulting strain to the fibre (such as the commercially available Temperature Compensation FBG sensors that are adjusted to steel 'carriers').…”

Temperature sensing in microwave heating of concrete using fibre Bragg grating sensors

“…The use of optical fibres as temperature sensors has been investigated by many researchers in different fields (Hirayama and Sano, 2000;Huang et al, 2003;Jung et al, 1998;Kersey and Berkoff, 1992;Kisaka et al, 2004;Lagakos et al, 1981;Pennisi et al, 2002;Protopopov et al, 2000;Ramesh and Wong, 1999;Seo and Kim, 1999;Silva et al, 2004;Wang et al, 2001;Lin et al, 2004;Zhan et al, 2004Zhan et al, , 2005. Several researchers developed optical-fibre-based temperature sensors by replacing a length of the optical fibre's cladding with a material that has a temperature-dependent refractive index (Pennisi et al, 2002).…”

“…In these studies, FBG sensors have been used mainly for the temperature monitoring of concrete structures (Wang et al, 2001) and laboratory specimens (Kuang et al, 2001;Wang et al, 2006;Lin et al, 2004) subjected to elevated temperatures in negligible or weak electromagnetic fields. There is very limited information on the potential of using FBG sensors to monitor concrete temperature in the presence of strong electromagnetic fields such as those present in microwave curing or microwave decontamination.…”

“…For this reason, an enormous number of fibre optic sensor types have been developed over a very short period of time. Recently, fibre Bragg grating (FBG) optical sensors have attracted a great deal of attention as reliable temperature and strain sensors, which have found widespread applications in civil engineering (Maher et al, 1996;Wang et al, 2001;Lin et al, 2004). These sensors relate the changes in the wavelength of the reflected wave to the desired measurand.…”

Optical fiber sensors embedded in concrete for measurement of temperature in a real fire test

“…In some works, embedded temperature sensors reached up to 150 • C inside concrete specimens. 3,4 In another publication, external temperature sensors were employed to measure gas temperature, reaching a maximum temperature of 300 • C. 5 Higher temperatures were measured in the experiments carried out by Heiberg et al, 6 but in this case, embedding optical fiber Bragg grating (FBG) sensors and thermocouples into aluminum alloys. To the best of our knowledge, this is the first experiment of a real test fire of concrete structures with embedded optical fiber Bragg grating sensors.…”