Analysis of Long-Term Deformation of Reinforced Retaining Wall Using Optical Fiber Sensor Geotextile

Geotextile have been widely used in the reinforced retaining wall, but it is not easy to measure the deformation of the wall during and after construction. To assess the deformation stability of the reinforced retaining wall, an optical fiber sensor was used in geotextile. Based on the measurement accuracy of strain for the sensor geotextile, an actual geotextile-reinforced retaining wall was studied using the fiber sensor geotextile. The experimental results were compared with the results from a numerical procedure, which employs the Mohr-Coulomb yield criterion and an initial stress method and determines the plastic displacement at collapse represented by the distribution of yield elements. The comparison shows that the numerical results have a good agreement with the corresponding measurement values. The result shows the possibility that the procedure gives the realistic evaluation of long-term deformation of reinforced retaining wall.

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An Optical Fiber Sensor Based on La2O2S:Eu Scintillator for Detecting Ultraviolet Radiation in Real-Time

Sensors ◽

10.3390/s18113754 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3754 ◽

Cited By ~ 3

Author(s):

Yongji Yan ◽

Xu Zhang ◽

Haopeng Li ◽

Yu Ma ◽

Tianci Xie ◽

...

Keyword(s):

Optical Fiber ◽

Response Time ◽

Electromagnetic Interference ◽

Uv Light ◽

Optical Fiber Sensor ◽

Temperature Response ◽

Superior Performance ◽

Fiber Sensor ◽

Uv Detectors

A novel ultraviolet (UV) optical fiber sensor (UVOFS) based on the scintillating material La2O2S:Eu has been designed, tested, and its performance compared with other scintillating materials and other conventional UV detectors. The UVOFS is based on PMMA (polymethyl methacrylate) optical fiber which includes a scintillating material. Scintillating materials provide a unique opportunity to measure UV light intensity even in the presence of strong electromagnetic interference. Five scintillating materials were compared in order to select the most appropriate one for the UVOFS. The characteristics of the sensor are reported, including a highly linear response to radiation intensity, reproducibility, temperature response, and response time (to pulsed light) based on emission from a UV source (UV fluorescence tube) centered on a wavelength of 308 nm. A direct comparison with the commercially available semiconductor-based UV sensor proves the UVOFS of this investigation shows superior performance in terms of accuracy, long-term reliability, response time and linearity.

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Analysis of Long-Term Prestress Loss in Prestressed Concrete (PC) Structures Using Fiber Bragg Grating (FBG) Sensor-Embedded PC Strands

Applied Sciences ◽

10.3390/app112412153 ◽

2021 ◽

Vol 11 (24) ◽

pp. 12153

Author(s):

Sung-Tae Kim ◽

Young-Soo Park ◽

Chul-Hwan Yoo ◽

Soobong Shin ◽

Young-Hwan Park

Keyword(s):

Optical Fiber ◽

Prestressed Concrete ◽

Optical Fiber Sensor ◽

Fiber Sensor ◽

Prestress Loss ◽

Fbg Sensor ◽

Embedded Pc ◽

Long Term Performance ◽

Term Performance

This study aims to develop a prestressed concrete steel (PC) strand with an embedded optical Fiber Bragg Grating (FBG) sensor, which has been developed by the Korea Institute of Civil Engineering and Building Technology since 2013. This new strand is manufactured by replacing the steel core of the normal PC strand with a carbon-fiber-reinforced polymer (CFRP) rod with excellent tensile strength and durability. Because this new strand is manufactured using the pultrusion method, which is a composite material manufacturing process, with an optical fiber sensor embedded in the inner center of the CFRP Rod, it ensures full composite action as well as proper function of the sensor. In this study, a creep test for maintaining a constant load and a relaxation test for maintaining a constant displacement were performed on the proposed sensor-type PC strand. Each of the two tests was conducted for more than 1000 h, and the long-term performance verification of the sensor-type PC strand was only completed by comparing the performance with that of a normal PC strand. The test specimens were fabricated by applying an optical fiber sensor-embedded PC strand, which had undergone long-term performance verification tests, to a reinforced concrete beam. Depending on whether grout was injected in the duct, the specimens were classified into composite and non-composite specimens. A hydraulic jack was used to prestress the fabricated beam specimens, and the long-term change in the prestress force was observed for more than 1600 days using the embedded optical fiber sensor. The experimental results were compared with the analytical results to determine the long-term prestress loss obtained through finite-element analysis based on various international standards.

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Noncontact Optical Fiber Sensor for Measuring the Refractive Index of Liquids

Journal of Sensors ◽

10.1155/2016/3475782 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

R. Selvas-Aguilar ◽

A. Castillo-Guzman ◽

L. Cortez-Gonzalez ◽

D. Toral-Acosta ◽

A. Martinez-Rios ◽

...

Keyword(s):

Refractive Index ◽

Laser Beam ◽

Optical Fiber ◽

Optical Fiber Sensor ◽

Theoretical Data ◽

Optical Power ◽

Fiber Sensor ◽

Liquid Sample ◽

Better Than ◽

Good Agreement

A noncontact optical fiber sensor for measuring the refractive index of transparent liquids is proposed. It operates by calculating the path of a focused laser beam at 635 nm that travels across the boundaries of a liquid sample. The optical power Fresnel reflections are detected and, subsequently, the refractive index is determined as the ratio between the traveled beam paths when the liquid is deposited versus a reference without the liquid sample. Additionally, a mathematical analysis of the geometrical case is included. The theoretical data from our sensor are in good agreement with the experimental results. The resolution achieved by the sensor is better than 10−3 RIU.

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