Fibre Bragg Gratings for the Monitoring of Wooden Structures

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.

Section: Introductionmentioning

confidence: 99%

Laboratory and In-Situ Testing of Integrated FBG Sensors for SHM for Concrete and Timber Structures

Čápová

Velebil

Včelák

2020

“…Wang [21] developed an SHM system and validated the feasibility by an experiment on a Tibetan heritage building. Marsili [22] raised a monitoring methodology for on-site behavior analysis of fiber-reinforced timber buildings. After analyzing the above references, we find that most of the existing FBG sensing-based SHM systems only focus on beam deformation monitoring.…”

Section: Introductionmentioning

confidence: 99%

Structural Health Monitoring System Based on FBG Sensing Technique for Chinese Ancient Timber Buildings

Jiang

Qiao

et al. 2019

Due to the long-term service, Chinese ancient timber buildings show varying degrees of wear. Thus, structural health monitoring (SHM) for these cultural and historical treasures is desperately needed to evaluate the service status. Although there are some FBG sensing-based SHM systems, they are not suitable for Chinese ancient timber buildings due to the differences in architectural types, structural loads, materials, and environment. Besides, a technical gap in Fiber Bragg grating (FBG) sensing-based column inclination monitoring exists. To overcome these weaknesses, this paper develops an FBG sensing-based structural health monitoring system for Chinese ancient Chuan-dou-type timber buildings that aims at monitoring structural deformation, i.e., beam deflection and column inclination, temperature, humidity, and fire around the building. An in-situ test and simulation analyses were conducted to verify the effectiveness of the developed SHM system. To validate the long-term-operation of the developed SHM system, monitoring data within 15 months were analyzed. The results show good agreement between the developed SHM system in this paper and other methods. In addition, the SHM system operated well in the first year after its deployment. This implies that the developed SHM system is applicable and effective in the health state monitoring of Chinese ancient Chuan-dou-type timber buildings, laying a foundation for damage prognosis of such types of timber buildings.

“…Actually, many of these sensing and monitoring methods have been gradually adopted to detect the deflection, inclination angle and strain for timber bridges and buildings [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 18 , 19 ]. Some new monitoring techniques were developed especially for museums and historic cultural heritage buildings [ 4 , 19 , 20 , 21 ]; furthermore, new techniques were employed to develop structural health monitoring (SHM) systems for the purpose of protecting historic cultural heritage and buildings [ 2 , 3 ]. For example, Feio et al [ 19 ] reviewed the application of visual strength grading standards in situ and the way the information could be combined with information provided by other nondestructive testing/semi-destructive testing methods to obtain a more reliable assessment of the mechanical performance of timber structural members.…”

Section: Introductionmentioning

confidence: 99%

Deformation Monitoring for Chinese Traditional Timber Buildings Using Fiber Bragg Grating Sensors

Jiang

et al. 2018

The Fiber Bragg Grating (FBG) sensing technique is suitable for a wide variety of measurements, including temperature, pressure, acceleration, liquid level, etc., and has been applied to many bridges and buildings in the past two decades. The fact that the FBG technique can only monitor and measure strain data for most cases when it is used for deformation measurements impedes application of the FBG sensing technique in civil infrastructures. This paper proposes FBG sensing-based deformation monitoring methods that are applicable to monitoring beam deflection, column inclination angle and mortise-tenon joint dislocation for Chinese traditional timber structures. On the basis of improved conjugated beam theory and geometrical trigonometric function relationship, the relationships between the FBG sensing strain values and the deflection of beam, inclination angle of column, as well as the amount of dislocation of mortise-tenon joint are deducted for Chinese traditional buildings. A series of experiments were conducted to verify the applicability and effectiveness of the proposed deformation monitoring methods. The results show that a good agreement is obtained between the values given by the methods proposed in this paper and other methods. This implies that the proposed deformation monitoring methods are applicable and effective in the health monitoring of Chinese traditional timber structures.