The vibration characteristics of a structure are defined by its modal properties comprising:
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Abstract Structural Health Monitoring SHM aims to develop automated systems for the continuous monitoring, inspection, and damage detection of structures with minimum labour involvement.
The first step to set up a SHM system is to incorporate a level of structural sensing capability that is reliable and possesses long term stability. Smart sensing technologies including the applications of fibre optic sensors, piezoelectric sensors, magnetostrictive sensors and self-diagnosing fibre reinforced composites, possess very important capabilities of monitoring various physical or chemical parameters related to the health and therefore, durable service life of structures.
In particular, piezoelectric sensors and magnetorestrictive sensors can serve as both sensors and actuators, which make SHM to be an active monitoring system.
Thus, smart sensing technologies are now currently available, and can be utilized to the SHM of civil engineering structures.
Introduction Civil engineering infrastructure is generally the most expensive national investment and asset of any country. In addition, civil engineering structures have long service life compared with other commercial products, and they are costly to maintain and replace once they are erected [ 1 ].
Further, there are few prototypes in civil engineering, and each structure leads to be unique in terms of materials, design, and construction. The most important structures include bridges, high-rise buildings, power utilities, nuclear power plants, and dams. All civil structures age and deteriorate with time.
The deterioration is mostly the result of aging of materials, continuous use, overloading, aggressive exposure Experimental study of structural vibration, lack of sufficient maintenance, and difficulties encountered in proper inspection methods.
All of these factors contribute to material and structural degradation as internal and external damages emerge and coalesce, and then evolve and progress.
To ensure structural integrity and safety, civil structures have to be equipped with Structural Health Monitoring SHMwhich aims to develop automated systems for the continuous monitoring, inspection, and damage detection of structures with minimum labour involvement [ 2 ].
An effective SHM system can in real time, and online, detect various defects and monitor strain, stress, and temperature so that the optimum maintenance of the structures can be carried out to ensure safety and durable service life. In general, a typical SHM system includes three major components: The first step to set up this system is to incorporate a level of stable and reliable structural sensing capability.
So, this paper is mainly related to the first component of the SHM system: Since shape memory alloys and magnetorheological fluids are often used as actuators, they are not introduced in this paper. FOS, for example, are small and therefore do not affect the performance characteristics of civil engineering structures in which they are embedded.
A single fibre can efficiently monitor structural performance at various locations by using multiplexed or distributed sensing technologies. They are unperturbed by electromagnetic interference. Optical waves are suitable for long transmission distances of relatively weak signals.
Piezoelectric and magnetorestrictive sensors can serve as both sensors and actuators, which make SHM to be an active monitoring system.
Furthermore, they can come in a variety of sizes, allowing them to be placed everywhere, even in remote and inaccessible locations, to actively monitor the conditions of various types of structures. It is beyond the scope of the paper to describe all the relevant theories involved, or to report all of practical applications examples.
The paper covers the major aspects of fibre optic sensors, piezoelectric sensors, self-diagnosing fibre reinforced composites, and magnetostrictive sensors for applications in civil engineering. Finally, the conclusions of this study are briefly reported.
The first method of classifying FOS is based on the light characteristics intensity, wavelength, phase, or polarization etc. The second method classifies an FOS by whether the light in the sensing segment is modified inside or outside the fiber intrinsic or extrinsic. This method of classification is adopted here.
FOS are generally surface mounted on existing structures, or embedded in newly constructed civil structures, including bridges, buildings, and dams, to yield information about strain static and dynamictemperature, defects delamination, cracks and corrosionand concentration of chloride ions.
The obtained data can be used to evaluate the safety of both new-built structures and repaired structures, and diagnose location and degree of damages.
In this section, the application of FOS in monitoring of strain, displacement and defects in civil engineering structures is reviewed. Other relevant details may be found in early reviews of FOS by Merzbacher et al. Monitoring of Strain and Displacement Laboratory studies have clarified some basic sensing properties of FOS in applications for civil engineering structures.
De Vires et al. Quirion and Ballivy [ 89 ] have evaluated the performance of the Fabry-Perot FOS when it was embedded in concrete cylinders. It can be observed that measured strains with the FOS are in good agreement with those measured by the electrical strain gauge and LVDT.
Zhang et al [ 10 ] conducted a repeated loading test on a concrete slab with embedded FOS. Four million cycles at a frequency of 2 Hz and 3 Hz were applied.
The sensors survived the 4 million loading cycles at a strain amplitude ofand showed good response to dynamic loading. Thus, strain concentrations were reduced, and no theoretical calibration factor had to be taken into account.
It also achieved continuous bonding to the concrete and allowed a symmetrical response under tensile and compressive loadings whatever the contact condition was.
Comparsion of concrete strains with various sesors [ 89 ].Aug 28, · light weight burnt bricks using rice husk and saw dust block wise studies of rural houses reinforced brick panel drinking water quality standards study in and around.
Noise and Vibration Analysis is a complete and practicalguide that combines both signal processing and modal analysistheory with their practical application in noise and vibrationanalysis. It provides an invaluable, integrated guide forpracticing engineers as well as a suitable introduction forstudents new to the topic of noise and vibration.
In order to study the validity of AMD system with rotating actuator in structural vibration control, we construct the experimental platform as depicted in Figure Single board dSPACE (RS) system is used as the. For many birds, skin coloration is the result of optical interactions with biological nanostructures or, in other words, the microscopic structure of skin (Figure 7).
Vibration (ISSN X) is a peer-reviewed open access journal of vibration science and engineering published quarterly online by MDPI..
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Structural Health Monitoring (SHM) aims to develop automated systems for the continuous monitoring, inspection, and damage detection of structures with minimum labour involvement.
The first step to set up a SHM system is to incorporate a level of structural sensing capability that is reliable and possesses long term stability. Smart sensing technologies including the applications of fibre.