Special Issue "Application of Fiber Reinforced Polymers in Strengthening of Reinforced Concrete Structures"

A special issue of Fibers (ISSN 2079-6439).

Deadline for manuscript submissions: closed (31 October 2019).

Special Issue Editor

Jun. Prof. Dr.-Ing. Akanshu Sharma
E-Mail Website1 Website2
Guest Editor
Innovative Verstärkungsmethoden mit Befestigungen, Institut für Werkstoffe im Bauwesen, Universität Stuttgart, Pfaffenwaldring 4, 70569 Stuttgart, Germany
Tel. +49-711-685-68034
Interests: inelastic static and dynamic analysis of reinforced concrete structures; static and dynamic testing of RC structures and sub-assemblages; seismic retrofitting of structures with innovative techniques; seismic behavior of cast-in and post-installed anchors in concrete; seismic performance assessment of RC structures; anchorages with supplementary reinforcement; numerical modeling of structures under seismic loads; modeling of anchorages for interaction between structure and equipment; impact behavior of reinforced concrete structures; fracture mechanics of concrete structures; modeling of bond between reinforcement and concrete; performance of RC structures subjected to fire loads
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Special Issue Information

Dear Colleagues,

Fiber-reinforced polymers (FRP) have gained a huge amount of popularity in the field of strengthening reinforced concrete (RC) structures over the last couple of decades. This is due to the several advantages that the fiber reinforcement offers over the conventional steel reinforcement. However, there are several issues and applications that are still open for research including but not limited to: (i) delamination of FRP and its prevention, (ii) optimizing the strengthening with FRP, (iii) combination of FRP with other strengthening methods, (iv) behavior of FRP at elevated temperatures, (v) application of FRP for the strengthening of deteriorated structures, etc.

This Special Issue will focus on the recent advancements in the application of FRP in the strengthening of RC structures. Through this call, I would like to invite researchers to present their latest research findings through high quality journal papers in the field of the FRP strengthening of RC structures for the benefit of researchers, engineers, industry and students.

Jun. Prof. Dr.-Ing. Akanshu Sharma
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fibers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Fiber-reinforced polymers
  • FRP wrapping
  • Strengthening
  • Delamination
  • Reinforcement
  • Near surface mounting

Published Papers (5 papers)

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Research

Open AccessArticle
Flexural Behavior of Hybrid-Reinforced Concrete Exterior Beam-Column Joints under Static and Cyclic Loads
Fibers 2019, 7(10), 94; https://doi.org/10.3390/fib7100094 - 22 Oct 2019
Abstract
This study presents an experimental investigation of the flexure behavior of exterior beam-column joints made from hybrid concrete (normal concrete (NC) and reactive powder concrete (RPC)) or hybrid reinforcement (steel and carbon fiber reinforced polymer (CFRP) bars internally or externally by near surface [...] Read more.
This study presents an experimental investigation of the flexure behavior of exterior beam-column joints made from hybrid concrete (normal concrete (NC) and reactive powder concrete (RPC)) or hybrid reinforcement (steel and carbon fiber reinforced polymer (CFRP) bars internally or externally by near surface mounted (NSM) technique). Nine hybrid-reinforced concrete beam-column joint specimens under the effect of static or cyclic loading were studied and tested within three test groups. Several variables that affect the behavior of the beam-column joint region are investigated such as: type of loading (static or cyclic), type of hybridization (concrete hybridization or reinforcement hybridization), and area of concrete hybridization. The results showed that using RPC as a replacement concrete at different areas of beam-column joint under static loading improved the ultimate load capacity and first cracking load to about 8–32% and 20–60%, respectively, compared with the reference NC joint with increase in the ductility of about 6–14%. Moreover, using the same technique under cyclic loading condition showed an increase in the ultimate load of about 39%, with improvement in the cumulative ductility of about 12% compared with the reference NC joint. On the other hand, using CFRP bars as (internal or external) hybridization system (33% of main reinforcement) under static loading caused increments of ultimate and first cracking loads of about 11%, 8% and 0%, 30%, respectively compared with the reference steel reinforced joint; while the ductility ratio increased about 36%, 5%, respectively. Moreover, the internal hybrid reinforcement system exhibited a decrease in the ultimate load of about 15% and reduction in the cumulative ductility of about 40% under cyclic loading. Full article
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Open AccessArticle
Effect of Cyclic Damage on the Performance of RC Square Columns Strengthened Using Hybrid FRP Composites under Axial Compression
Fibers 2019, 7(10), 90; https://doi.org/10.3390/fib7100090 - 14 Oct 2019
Abstract
The effectiveness of hybrid fibre-reinforced polymer (FRP) strengthening is evaluated for rapid repair of the pre-damaged plain concrete (PC) and reinforced concrete (RC) columns. The objective of this study is to understand the efficiency of hybrid technique for completely restoring the initial stiffness, [...] Read more.
The effectiveness of hybrid fibre-reinforced polymer (FRP) strengthening is evaluated for rapid repair of the pre-damaged plain concrete (PC) and reinforced concrete (RC) columns. The objective of this study is to understand the efficiency of hybrid technique for completely restoring the initial stiffness, load carrying capacity and ductility of pre-damaged columns under cyclic compression loads. Two series of PC and RC square columns were cast. The columns were pre-damaged by loading up to 80% of peak load capacity for three cycles under pure compression. After cyclic damage, the columns were strengthened with two techniques, namely (a) near-surface mounted (NSM) carbon FRP (CFRP) laminates and (b) hybrid FRP technique, which uses a combination of NSM and externally bonded (EB) CFRP fabric. Analytical modelling was carried out for predicting the behaviour of columns with initial cyclic pre-damage. Additionally, a phased three-dimensional nonlinear finite element (FE) analysis was performed to validate the behaviour of pre-damaged columns with different strengthening techniques. Test results show that cyclic pre-loading and resulting damage causes a reduction in axial stiffness of all damaged specimens. Hybrid strengthening completely restored the stiffness and strength under compression. Prediction of analytical and FE analysis correlated well with the tests. Full article
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Open AccessFeature PaperArticle
Performance of Concrete Confined with a Jute–Polyester Hybrid Fiber Reinforced Polymer Composite: A Novel Strengthening Technique
Fibers 2019, 7(8), 72; https://doi.org/10.3390/fib7080072 - 08 Aug 2019
Abstract
The strengthening and rehabilitation of concrete members is an important issue which arises worldwide. Carbon, aramid and glass fiber reinforced polymer (FRP) composites are mainly used for strengthening and rehabilitation. However, its use is limited on a small scale because of its high [...] Read more.
The strengthening and rehabilitation of concrete members is an important issue which arises worldwide. Carbon, aramid and glass fiber reinforced polymer (FRP) composites are mainly used for strengthening and rehabilitation. However, its use is limited on a small scale because of its high price, lack of availability and environmental impacts. The solution of this issue gives rise to the use of locally available natural fibers and low-cost synthetic fibers. This paper presents the experimental and analytical results of circular and square concrete columns confined with jute–polyester hybrid FRP composites. The main objective of this study is to evaluate the viability and performance of concrete confined with the hybridization of jute and polyester (FRP) composite sheets to utilize its superior properties. A novel hybrid technique has been applied for the wrapping of fiber sheets. The fiber sheets were applied in such a way that a uniform bond between the inner and outer layer was achieved. A total of 32 plain, standard size circular and square concrete specimens, externally wrapped with a jute–polyester FRP (JPFRP) composite, were tested under monotonic axial compressive loads. The result shows that JPFRP confinement increased the strength, strain and ductility index ranged between 1.24 and 2.61, 1.38 and 8.97, and 4.94 and 26.5 times the un-jacketed specimen, respectively. Furthermore, the wrapping has a significant effect on the low-strength specimens, having a circular cross-section. For high strength specimens, the post-peak stress-strain behavior was dominated by the outer polyester jacket because of its large rupture strain. Additionally, the test results were used to evaluate the existing strength-strain models derived for conventional FRPs. The models predicted values either underestimating or overestimating the compressive strength and strain of JPFRP-confined specimens. However, the strength models performed better than the strain models. The JPFRP wrapping significantly enhanced the strength, fracture energy, ductility index, and post-peak response. Therefore, JPFRP confinement can be used for a small-scale application, where little strength and high ductility is demanded. Moreover, it can be used to prevent the peeling of the concrete cover and moisture penetration into the concrete. Full article
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Open AccessArticle
Composite Performance Evaluation of Basalt Textile-Reinforced Geopolymer Mortar
Fibers 2019, 7(7), 63; https://doi.org/10.3390/fib7070063 - 11 Jul 2019
Cited by 1
Abstract
Basalt fiber is a novel type of inorganic fiber which is produced from the extrusion of natural vocalnic basalt rocks through their melting process at high temperature. So the quality and strength characteristics of basalt fiber depend mainly on both the quality of [...] Read more.
Basalt fiber is a novel type of inorganic fiber which is produced from the extrusion of natural vocalnic basalt rocks through their melting process at high temperature. So the quality and strength characteristics of basalt fiber depend mainly on both the quality of raw material and manufacturing processing. Basalt fabric-reinforced cementitious composites (FRCM) are a novel composite and an extensive scientific investigation is still ongoing for geopolymer composite. Based on three types of basalt textile with respect to various net sizes, the aim of this paper is to evaluate the flexural performance of basalt textile-reinforced geopolymer composite through the four-point bending test. The specimens of rectangular form with the dimension of 400 × 100 × 15 mm3, reinforced with one to four layers of each type of basalt textile, were produced. They were then tested at the age of about 40 days after casting. On the other hand, the number of the specimens reinforced with four layers were considered to assess the mechanical strength of the specimens at longer periods of ageing time (60, 90, 150, 180 days). The experimental results showed that with the increasing number of reinforcing layers, the specimens significantly improved the mechanical strength, except for those reinforced with basalt textile of big net size. The specimens reinforced with basalt textile of big net size had no impact on post-crack mechanical strength, however, it helps to arrest the catastrophic brittle failure of the specimens; the failure of these specimens is due to localization of first crack. When the specimens were exposed to the further ageing times, the mechanical strength of the specimens were decreased over time. All the reinforced specimens have the same failure mode by flexural failure due to the rupture of fiber yarn in matrix, and no debonding of fiber yarn or a gradual peeling process of mortar matrix happened during testing. Full article
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Open AccessArticle
External Strengthening of Corrosion-Defected Beam–Column Members Using a CFRP Sheet
Fibers 2019, 7(6), 53; https://doi.org/10.3390/fib7060053 - 07 Jun 2019
Abstract
The efficiency of external strengthening using CFRP (Carbon Fiber Reinforced Polymer) sheets to rehabilitate corrosion-defected RC (Reinforced Concrete) beam–column members is experimentally studied. ALL specimens were tested under a combined axial force and transverse load until failure. The axial forces were applied with [...] Read more.
The efficiency of external strengthening using CFRP (Carbon Fiber Reinforced Polymer) sheets to rehabilitate corrosion-defected RC (Reinforced Concrete) beam–column members is experimentally studied. ALL specimens were tested under a combined axial force and transverse load until failure. The axial forces were applied with two levels either 25% or 50% of the ultimate design load of control specimen. The accelerated corrosion process was used to get steel reinforcement corrosion inside the concrete at three levels, 0% and approximately 5% and 20%, according to Faraday’s law. External strengthening with a CFRP sheet was used in this study to overcome the effect of deterioration in the mechanical properties of the corroded steel bars. A significant deterioration in the load carrying capacity, stiffness, and serviceability was recorded for corrosion-defected specimens. The increase of the axial force was recorded as a positive effect on the ultimate strength, stiffness, and serviceability of the testing specimens. This effect was clearly evident for the defected specimens, with an increasing corrosion level, by decreasing the adverse effects of corrosion. The external strengthening with a CFRP sheet restored the load-carrying capacity, stiffness, and serviceability to an undamaged state. Full article
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