Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar

FRP-confined concrete core-encased rebar (FCCC-R) is a novel composite structure that has recently been proposed to effectively delay the buckling of ordinary rebar and enhance its mechanical properties by utilizing high-strength mortar or concrete and an FRP strip to confine the core. The purpose o...

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Main Authors: Jingzhou Lu, Tong Mou, Chen Wang, Han Huang, Wenyu Han
Format: Article
Language:English
Published: MDPI AG 2023-06-01
Series:Polymers
Subjects:
Online Access:https://www.mdpi.com/2073-4360/15/12/2728
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author Jingzhou Lu
Tong Mou
Chen Wang
Han Huang
Wenyu Han
author_facet Jingzhou Lu
Tong Mou
Chen Wang
Han Huang
Wenyu Han
author_sort Jingzhou Lu
collection DOAJ
description FRP-confined concrete core-encased rebar (FCCC-R) is a novel composite structure that has recently been proposed to effectively delay the buckling of ordinary rebar and enhance its mechanical properties by utilizing high-strength mortar or concrete and an FRP strip to confine the core. The purpose of this study was to study the hysteretic behavior of FCCC-R specimens under cyclic loading. Different cyclic loading systems were applied to the specimens and the resulting test data were analyzed and compared, in addition to revealing the mechanism of elongation and mechanical properties of the specimens under the different loading systems. Furthermore, finite-element simulation was performed for different FCCC-Rs using the ABAQUS software. The finite-element model was also used for the expansion parameter studies to analyze the effects of different influencing factors, including the different winding layers, winding angles of the GFRP strips, and the rebar-position eccentricity, on the hysteretic properties of FCCC-R. The test result indicates that FCCC-R exhibits superior hysteretic properties in terms of maximum compressive bearing capacity, maximum strain value, fracture stress, and envelope area of the hysteresis loop when compared to ordinary rebar. The hysteretic performance of FCCC-R increases as the slenderness ratio is increased from 10.9 to 24.5 and the constraint diameter is increased from 30 mm to 50 mm, respectively. Under the two cyclic loading systems, the elongation of the FCCC-R specimens is greater than that of ordinary rebar specimens with the same slenderness ratio. For different slenderness ratios, the range of maximum elongation improvement is about 10% to 25%, though there is still a large discrepancy compared to the elongation of ordinary rebar under monotonic tension. Despite the maximum compressive bearing capacity of FCCC-R is improved under cyclic loading, the internal rebars are more prone to buckling. The results of the finite-element simulation are in good agreement with the experimental results. According to the study of expansion parameters, it is found that the hysteretic properties of FCCC-R increase as the number of winding layers (one, three, and five layers) and winding angles (30°, 45°, and 60°) in the GFRP strips increase, while they decrease as the rebar-position eccentricity (0.15, 0.22, and 0.30) increases.
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spelling doaj.art-f989fc28f5154070881d93bb7889fc312023-11-18T12:13:56ZengMDPI AGPolymers2073-43602023-06-011512272810.3390/polym15122728Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased RebarJingzhou Lu0Tong Mou1Chen Wang2Han Huang3Wenyu Han4School of Civil Engineering, Yantai University, Yantai 264005, ChinaSchool of Civil Engineering, Yantai University, Yantai 264005, ChinaSchool of Civil Engineering, Yantai University, Yantai 264005, ChinaSchool of Civil Engineering, Yantai University, Yantai 264005, ChinaSchool of Civil Engineering, Yantai University, Yantai 264005, ChinaFRP-confined concrete core-encased rebar (FCCC-R) is a novel composite structure that has recently been proposed to effectively delay the buckling of ordinary rebar and enhance its mechanical properties by utilizing high-strength mortar or concrete and an FRP strip to confine the core. The purpose of this study was to study the hysteretic behavior of FCCC-R specimens under cyclic loading. Different cyclic loading systems were applied to the specimens and the resulting test data were analyzed and compared, in addition to revealing the mechanism of elongation and mechanical properties of the specimens under the different loading systems. Furthermore, finite-element simulation was performed for different FCCC-Rs using the ABAQUS software. The finite-element model was also used for the expansion parameter studies to analyze the effects of different influencing factors, including the different winding layers, winding angles of the GFRP strips, and the rebar-position eccentricity, on the hysteretic properties of FCCC-R. The test result indicates that FCCC-R exhibits superior hysteretic properties in terms of maximum compressive bearing capacity, maximum strain value, fracture stress, and envelope area of the hysteresis loop when compared to ordinary rebar. The hysteretic performance of FCCC-R increases as the slenderness ratio is increased from 10.9 to 24.5 and the constraint diameter is increased from 30 mm to 50 mm, respectively. Under the two cyclic loading systems, the elongation of the FCCC-R specimens is greater than that of ordinary rebar specimens with the same slenderness ratio. For different slenderness ratios, the range of maximum elongation improvement is about 10% to 25%, though there is still a large discrepancy compared to the elongation of ordinary rebar under monotonic tension. Despite the maximum compressive bearing capacity of FCCC-R is improved under cyclic loading, the internal rebars are more prone to buckling. The results of the finite-element simulation are in good agreement with the experimental results. According to the study of expansion parameters, it is found that the hysteretic properties of FCCC-R increase as the number of winding layers (one, three, and five layers) and winding angles (30°, 45°, and 60°) in the GFRP strips increase, while they decrease as the rebar-position eccentricity (0.15, 0.22, and 0.30) increases.https://www.mdpi.com/2073-4360/15/12/2728FCCC-Rhysteretic behaviorcyclic loadingrebar buckling
spellingShingle Jingzhou Lu
Tong Mou
Chen Wang
Han Huang
Wenyu Han
Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
Polymers
FCCC-R
hysteretic behavior
cyclic loading
rebar buckling
title Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
title_full Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
title_fullStr Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
title_full_unstemmed Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
title_short Research on Hysteretic Behavior of FRP-Confined Concrete Core-Encased Rebar
title_sort research on hysteretic behavior of frp confined concrete core encased rebar
topic FCCC-R
hysteretic behavior
cyclic loading
rebar buckling
url https://www.mdpi.com/2073-4360/15/12/2728
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