• Steel and Composite Structures
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• v.21 no.6
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• pp.1265-1285
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• 2016

This paper presents experimental results of advanced investigation carried out on the beams reinforced with Glass Fiber Reinforced Polymer (GFRP) rebar and stirrups. Twelve beams reinforced with GFRP and one beam with steel reinforcement of size $230{\times}300{\times}2000mm$ were investigated. Longitudinal reinforcement, shear span and spacing of stirrups were the main variables to form the set. In advanced testing three types of strain gauges for steel, composite and concrete surface were applied to observe strain/stress development against the applied load. Live data were recorded from four strain gauges applied on stirrups, one at center on longitudinal reinforcement, two on the concrete surface and central deflection during the test. Although the focus of the paper was mainly on the behavior of GFRP shear reinforcement, other parallel data were observed for the completeness of the test. Design recommendations of ISIS Canada Design Manual (2007), Japan Society of Civil Engineers (1997) and American Concrete Institute (ACI-440.1R-06) were reviewed. Shear design predictions were compared with experimental results in which it was observed that all the three standards provided conservative predictions. However, ACI found most efficient compare to other two there is room to improve the efficiency of the recommendations.

• The Journal of Advanced Prosthodontics
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• v.8 no.2
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• pp.116-124
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• 2016

PURPOSE. The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments. MATERIALS AND METHODS. Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); $0^{\circ}$, group II; $10^{\circ}$, group III; $20^{\circ}$, and group IV; $30^{\circ}$. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group $IV_{red}$). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading. RESULTS. For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group $IV_{red}$ showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading. CONCLUSION. Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.312-318
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• 2013

PURPOSE. The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS. A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ${\alpha}$=.05. RESULTS. The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 ${\mu}m/m$ at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION. Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.605-614
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• 2010

In this paper, the initial behavior of transmission tower was analyzed. This tower was firstly constructed by rock anchor foundation in domestic 154 kV transmission line and wireless real-time monitoring system was installed to obtain the measured data for analysis of the structure behavior. For this purpose, 16 strain gauges was installed in anchors of foundation and strain gauges, clinometers, anemoscope and settlement sensors was installed at superstructure. As the results, the main factor which influence the behavior of superstructure is wind velocity, wind direction, rainfall and temperature change. Especially, the uplift load at stub of transmission structure revealed about 35.4 percentages of design load. Hereafter the long term stability will be analyzed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.82-88
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• 2006

In People usually think that smart materials and smart structures have not been developed until recent years. But those kinds of sensors have already been used for sensing damage in a variety of materials and structures. Two typical examples are piezoelectric materials (e.g., PZT) and electric strain gauges. Load cell is an example that utilizes the piezoelectric property to measure the change in physical quantities occurred by applied loads, while strain gauges are used to measure the deformation of compressive and tension members. The feasibility of using smart materials is realized for a monitoring technology when those sensors are used to monitor damages at inside or outsider of the structures. In this study, a fundamental study on the development of self diagnostic smart concrete using PZT, and unsaturated polyester electric resistance sensor.

• Journal of the Korean Solar Energy Society
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• v.24 no.4
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• pp.27-33
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• 2004

Mechanical load measurements on blade and tower of Vestas 100 kW wind turbine has been reformed in Wollyong test site, Jeju island. The experimental procedure for the measurement of wind turbine loads, such as edgewise(lead-lag) bending moment, flapwise bending moment, and tower base bending moment, has been established. The test facilities consisting of strain-gauges, telemetry and T-Mon system are installed in the wind turbine. Strain gauges are on-site calibrated against load cell prior to monitoring the wind turbine loads. Using the test setup, the loads on the components are being measured and analysed for various external conditions of the wind turbine. A set of results for near rated wind speed has been presented in this paper.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.161-170
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• 1999

The KLCC Petronas Tower 2, one of the world tallest twin reinforced concrete towers constructed in Kuala Lumpur, Malysia, was instrumented during construction for the measurement of vertical time-dependent deformation of columns and corewall. Field measurements were made by means of vibrating wire strain gauges at the corewall, tower and bustle perimeter columns at selected floor levels of the building. Parallel to this observation, laboratory tests were performed on concrete cylinders made in the field in order to obtain the variations of concrete compressive strengths, elastic moduli, strains of creep and shrinkage with time. Monitored vertical deformations are in a good agreement with the prediction based on actual construction sequence and concrete properties from laboratory tests, as well as the analytical results reflected in actual column compensation of the building.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.192-196
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• 2002

This paper describes on the fabrication and characteristics of a metal thin-film pressure sensor based on Cr strain-gauges for harsh environment applications. The Cr thin-film strain-gauges are sputter-deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Cr thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097~1.21 $mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• Composites Research
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• v.16 no.6
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• pp.56-61
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• 2003

In this Paper, a fiber Bragg grating(FBG) sensor system is described and FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system. a reflect wave-length measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. We apply the FBG system to nuclear energy Power Plant for structural integrity test to measure the displacement of the structure under designed pressure and to check the elasticity of the structure by measuring the residual strain. The system works very well and it is expected that it can be used for a real-time strain, temperature and vibration detector of smart structure.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.169-174
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• 1996

It have been announced that concrete subjected to freezing and thawing cause deterioration by expanded inside water and contracted at thawing. However, this study descrebe the deterioration mechanism of concrete by freezing and thawing test. Embeded strain gauges were used to measure the inside restrict strain due to the temperature differenct inside and outside the concrete test specimens. Test results showed that using the air entrained admixture and expanded poly-styrene was developed durability of concrete by decreasing inside retrict strain ratio.