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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Smart Structures and Systems
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Volume 1, Issue 4 - Oct 2005
Volume 1, Issue 3 - Sep 2005
Volume 1, Issue 2 - Apr 2005
Volume 1, Issue 1 - Jan 2005
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Versatile robotic platform for structural health monitoring and surveillance
Esser, Brian ; Huston, Dryver R. ;
Smart Structures and Systems, volume 1, issue 4, 2005, Pages 325~338
DOI : 10.12989/sss.2005.1.4.325
Utilizing robotic based reconfigurable nodal structural health monitoring systems has many advantages over static or human positioned sensor systems. However, creating a robot capable of traversing a variety of civil infrastructures is a difficult task, as these structures each have unique features and characteristics posing a variety of challenges to the robot design. This paper outlines the design and implementation of a novel robotic platform for deployment on ferromagnetic structures as an enabling structural health monitoring technology. The key feature of this design is the utilization of an attachment device which is an advancement of the common magnetic base found in the machine tool industry. By mechanizing this switchable magnetic circuit and redesigning it for light weight and compactness, it becomes an extremely efficient and robust means of attachment for use in various robotic and structural health monitoring applications. The ability to engage and disengage the magnet as needed, the very low power required to do so, the variety of applicable geometric configurations, and the ability to hold indefinitely once engaged make this device ideally suited for numerous robotic and distributed sensor network applications. Presented here are examples of the mechanized variable force magnets, as well as a prototype robot which has been successfully deployed on a large construction site. Also presented are other applications and future directions of this technology.
Health monitoring of steel structures using impedance of thickness modes at PZT patches
Park, Seunghee ; Yun, Chung-Bang ; Roh, Yongrae ; Lee, Jong-Jae ;
Smart Structures and Systems, volume 1, issue 4, 2005, Pages 339~353
DOI : 10.12989/sss.2005.1.4.339
This paper presents the results of a feasibility study on an impedance-based damage detection technique using thickness modes of piezoelectric (PZT) patches for steel structures. It is newly proposed to analyze the changes of the impedances of the thickness modes (frequency range > 1 MHz) at the PZT based on its resonant frequency shifts rather than those of the lateral modes (frequency range > 20 kHz) at the PZT based on its root mean square (RMS) deviations, since the former gives more significant variations in the resonant frequency shifts of the signals for identifying localities of small damages under the same measurement condition. In this paper, firstly, a numerical analysis was performed to understand the basics of the NDE technique using the impedance using an idealized 1-D electro-mechanical model consisting of a steel plate and a PZT patch. Then, experimental studies were carried out on two kinds of structural members of steel. Comparisons have been made between the results of crack detections using the thickness and lateral modes of the PZT patches.
Applications of fiber optic sensors for structural health monitoring
Kesavan, K. ; Ravisankar, K. ; Parivallal, S. ; Sreeshylam, P. ;
Smart Structures and Systems, volume 1, issue 4, 2005, Pages 355~368
DOI : 10.12989/sss.2005.1.4.355
Large and complex structures are being built now-a-days and, they are required to be functional even under extreme loading and environmental conditions. In order to meet the safety and maintenance demands, there is a need to build sensors integrated structural system, which can sense and provide necessary information about the structural response to complex loading and environment. Sophisticated tools have been developed for the design and construction of civil engineering structures. However, very little has been accomplished in the area of monitoring and rehabilitation. The employment of appropriate sensor is therefore crucial, and efforts must be directed towards non-destructive testing techniques that remain functional throughout the life of the structure. Fiber optic sensors are emerging as a superior non-destructive tool for evaluating the health of civil engineering structures. Flexibility, small in size and corrosion resistance of optical fibers allow them to be directly embedded in concrete structures. The inherent advantages of fiber optic sensors over conventional sensors include high resolution, ability to work in difficult environment, immunity from electromagnetic interference, large band width of signal, low noise and high sensitivity. This paper brings out the potential and current status of technology of fiber optic sensors for civil engineering applications. The importance of employing fiber optic sensors for health monitoring of civil engineering structures has been highlighted. Details of laboratory studies carried out on fiber optic strain sensors to assess their suitability for civil engineering applications are also covered.
Embedded smart GFRP reinforcements for monitoring reinforced concrete flexural components
Georgiades, Anastasis V. ; Saha, Gobinda C. ; Kalamkarov, Alexander L. ; Rokkam, Srujan K. ; Newhook, John P. ; Challagulla, Krishna S. ;
Smart Structures and Systems, volume 1, issue 4, 2005, Pages 369~384
DOI : 10.12989/sss.2005.1.4.369
The main objectives of this paper are to demonstrate the feasibility of using newly developed smart GFRP reinforcements to effectively monitor reinforced concrete beams subjected to flexural and creep loads, and to develop non-linear numerical models to predict the behavior of these beams. The smart glass fiber-reinforced polymer (GFRP) rebars are fabricated using a modified pultrusion process, which allows the simultaneous embeddement of Fabry-Perot fiber-optic sensors within them. Two beams are subjected to static and repeated loads (until failure), and a third one is under long-term investigation for assessment of its creep behavior. The accuracy and reliability of the strain readings from the embedded sensors are verified by comparison with corresponding readings from surface attached electrical strain gages. Nonlinear finite element modeling of the smart concrete beams is subsequently performed. These models are shown to be effective in predicting various parameters of interest such as crack patterns, failure loads, strains and stresses. The strain values computed by these numerical models agree well with corresponding readings from the embedded fiber-optic sensors.
Crack mapping in RC members using distributed coaxial cable crack sensors: modeling and application
Greene, Gary Jr. ; Belarbi, Abdeldjelil ; Chen, Genda ;
Smart Structures and Systems, volume 1, issue 4, 2005, Pages 385~404
DOI : 10.12989/sss.2005.1.4.385
The paper presents a model to calculate reinforcement strain using measured crack width in members under applied tension, flexure, and/or shear stress. Crack mapping using a new type of distributed coaxial cable sensors for health monitoring of large-scale civil engineering infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to cyclic combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor`s response to strain in the member, and show that magnitude of the signal`s reflection coefficient is related to increases in applied load, repeated cycles, cracking, and reinforcement yielding. The effect of multiple adjacent cracks, and signal loss was also investigated. The results shown in this paper are an important step in using the sensors for crack mapping and determining reinforcement strain for in-situ structures.