scholarly journals Smart Sensing of PSC Girders Using a PC Strand with a Built-in Optical Fiber Sensor

2021 ◽  
Vol 11 (1) ◽  
pp. 359
Author(s):  
Sung Tae Kim ◽  
Hyejin Yoon ◽  
Young-Hwan Park ◽  
Seung-Seop Jin ◽  
Soobong Shin ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Prestressed Concrete ◽  
Steel Wire ◽  
Optical Fiber Sensor ◽  
Fiber Reinforced Polymer ◽  
Bridge Structure ◽  
Fbg Sensor ◽  
Prestressing Force ◽  
Reinforced Polymer ◽  
Loading Tests

This paper presents a multi-functional strand capable of introducing prestressing force in prestressed concrete (PSC) girders and sensing their static and dynamic behavior as well. This innovative strand is developed by replacing the core steel wire of the strand used in PSC structures with a carbon fiber-reinforced polymer (CFRP) wire with a built-in optical Fiber Bragg Grating (FBG) sensor. A full-scale girder specimen was fabricated by applying this multi-function strand to check the possibility of tracking the change of prestressing force at each construction stage. Moreover, dynamic data could be secured during dynamic loading tests without installing accelerometers and made it possible to obtain the natural frequencies of the structure. The results verified the capability to effectively manage the prestressing force in the PSC bridge structure by applying the PC strand with a built-in optical sensor known for its outstanding practicability and durability.

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

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.

Cure Monitoring of Composites Based on Embedded Fiber Bragg Gratings

2011 ◽  
Vol 211-212 ◽  
pp. 585-589 ◽  
Author(s):  
Xiao Yan Shen
Keyword(s):  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Cure Process ◽  
Cfrp Laminates ◽  
Cure Monitoring ◽  
Fbg Sensor ◽  
Reinforced Polymer ◽  
Before And After ◽  
Fbg Sensors ◽  
The Difference

Cure-induced strain is produced inevitably during the fabrication of the composite. To measure the strain, undamaged methods such as using fiber Bragg grating(FBG) sensor are employed. In this paper, nine unidirectional carbon fiber-reinforced polymer(CFRP) laminates are autoclaved produced, with FBGs embedded in different layers through the thickness (0-layer, 5-layer, 10-layer and 13-layer). The experiment measures the difference of the FBGs’ Bragg wavelengths before and after the cure which is linearly relevant to the cure-induced strain, to explore the distribution of strains through the thickness. The experimental results indicate a certain strain in neural plane of approximately 370με under the designed size of the laminates. The results also show that the cure-induced strains in different layers through the thickness are less than 1000με even including all errors, however they do not display distinct regular in thickness direction. Moreover, through the FBG sensors and the thermocouples, the cure process with the strain and temperature variations is understood well. The result verifies that the cure-induced strain is mainly generated at the end of the cure when the temperature cools down.

Transverse shear properties of fiber reinforced polymer bars with different reinforced phases

2021 ◽  
pp. 002199832110316
Author(s):  
Danying Gao ◽  
Yu Zhang ◽  
Fangzheng Wen ◽  
Yuyang Pang ◽  
Dong Fang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Glass Fiber ◽  
Distribution Pattern ◽  
Steel Wire ◽  
Ultimate Strain ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Surface Configuration

In this study, a total of 105 shear specimens of fiber reinforced polymer bars with different reinforced phases, including the glass fiber, the hybrid of carbon fiber with glass fiber, and the hybrid of steel wire with glass fiber, were prepared to systematically investigate their transverse shear properties. The surface configuration of specimens, the performance characteristics and distribution pattern of reinforced phase were mainly regarded as variables. The results showed the shear strengths of glass fiber reinforced polymer bar specimens increased from 247.9 MPa to 263.5 MPa as the rib depth changed from shallow ribs to deep ribs, and their ultimate strain decreased from 0.374 to 0.328 with the increase in rib spacing from 8 mm to 16 mm. The shear strengths of carbon/glass hybrid fiber reinforced polymer (C/G HFRP) bar specimens declined from 247.4 MPa to 226.3 MPa as the distribution pattern of carbon fiber changed from centralized distribution to dispersed distribution. The shear strength of C/G HFRP bars decreased from 256.5 MPa to 247.4 MPa as the ratio of glass fiber to carbon fiber ranged from 0:1 to 1:4, and increased from 138.7 MPa to 214.8 MPa for steel wire/glass HFRP bars as the volumetric fraction of steel wire replacing glass fiber increased from 0 to 33.3%. This indicated that the surface configuration of specimen, the distribution pattern of fiber, and the performance characteristics of reinforced phase have great effects on the ultimate strain and shear strength of FRP bars, respectively.

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