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Experimental and Numerical Advancements on Strengthening of Concrete Structures with...
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Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers

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

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 32825

Special Issue Editor

Dr. Akanshu Sharma

E-Mail Website
Guest Editor
Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907-2051, USA
Interests: performance based design of RC 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; 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; structural applications of new concrete based materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Due to their high strength to weight ratio, fiber-reinforced polymers (FRP) are often used to strengthen concrete structures against various kinds of loading scenarios. Although the material by itself displays a brittle response, a good application can lead to an overall ductile response and an enhanced performance from the system, e.g., due to beneficial effects such as confinement. Although several studies have shown the potential of FRP in strengthening structural elements, there are several issues and applications that are still open for research. Some of them include: (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 strengthening of deteriorated structures, etc. Furthermore, since research to date has primarily focused on experimental studies, studies on numerical modeling methods are rather scarce. Good numerical and analytical methods are required to understand the mechanics of FRP-strengthened structural elements and also for a safe and reliable design of strengthening using FRP.

This issue focuses on recent advancements in the application of FRP in strengthening 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 FRP strengthening of RC structures for the benefit of researchers, engineers, industry, and students.

Dr. Akanshu Sharma
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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 2000 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
  • Reinforced concrete structures
  • Strengthening
  • Numerical modeling
  • Experimental methods
  • Finite element methods
  • Performance enhancement

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Published Papers (7 papers)

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Research

18 pages, 21481 KiB  
Article
Flexural Strengthening of RC Continuous T-Beams Using CFRP
by Ayssar Al-Khafaji and Hani Salim
Fibers 2020, 8(6), 41; https://doi.org/10.3390/fib8060041 - 20 Jun 2020
Cited by 26 | Viewed by 5624
Abstract
In this paper, experimental investigations for strengthening reinforced concrete (RC) continuous beams were performed. Eighteen T-beams were cast, twelve of which were inverted T-beams where the flange portion of the T-beam was subjected to positive flexure to represent the support region of a [...] Read more.
In this paper, experimental investigations for strengthening reinforced concrete (RC) continuous beams were performed. Eighteen T-beams were cast, twelve of which were inverted T-beams where the flange portion of the T-beam was subjected to positive flexure to represent the support region of a continuous beam. Six of the T-beams were non-inverted where the web is subjected to positive flexure. Carbon fiber reinforced polymer (CFRP) sheets with different widths were considered, and different strengthening configurations with the same area of CFRP were investigated. The use of one-layer, multiple layers, or multiple strips of CFRP were evaluated to investigate the effect of these configurations on the ultimate capacity and ductility of the strengthened beams. From the experimental observation of the non-inverted beams, it was found that the ultimate load capacities of the CFRP-strengthened beams were enhanced by 4% to 90% compared to the control beam. Using multiple layers of CFRP sheets enhanced the stiffness of the beams by 4% to 46%, depending on the CFRP area and configurations. The debonding of CFRP before the ultimate failure provided additional ductility to the tested beams. For the strengthening of the inverted beams, it was found that the addition of CFRP strips did not increase the strength of the beams when the width of CFRP to beam width ratio was less than 0.25, but the ductility of the beam was enhanced slightly. The use of multiple strips was found to be a more effective way for the strengthening of the negative moment region than using multiple layers. This can also provide more desirable modes of failure than when applying CFRP in multiple layers. Ductility was found to be lower if multiple layers were used compared to other configurations. Moreover, it was observed that as the compressive strength of concrete increased the addition of the CFRP improved the beams ductility. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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21 pages, 5924 KiB  
Article
Experimental Study on the Effectiveness of Inorganic Bonding Materials for Near-Surface Mounting Shear Strengthening of Prestressed Concrete Beams
by Vikas Singh Kuntal, M. Chellapandian, S. Suriya Prakash and Akanshu Sharma
Fibers 2020, 8(6), 40; https://doi.org/10.3390/fib8060040 - 17 Jun 2020
Cited by 25 | Viewed by 3964
Abstract
Use of organic resins such as epoxy and vinyl esters as bonding materials in fibre reinforced polymer (FRP) strengthening of concrete members is widely accepted. However, the performance of organic resins is compromised when exposed to high temperature and extreme weather conditions leading [...] Read more.
Use of organic resins such as epoxy and vinyl esters as bonding materials in fibre reinforced polymer (FRP) strengthening of concrete members is widely accepted. However, the performance of organic resins is compromised when exposed to high temperature and extreme weather conditions leading to reduced durability of the strengthened systems. The present study attempts to evaluate the effectiveness of inorganic (cement mortar and geopolymer mortar) bonding materials for shear strengthening of prestressed concrete (PSC) beams using the near-surface mounting (NSM) technique. Different types of bonding materials are used in this study for NSM shear strengthening including: (i) epoxy resin, (ii) high strength cement grout (HSCG) and (iii) geopolymer mortar. Bond tests were first conducted to evaluate the pull-out/bond strength of different bonding materials. Bond tests revealed that epoxy resin had the highest bond strength followed by geopolymer mortar and HSCG. Sixteen full-scale PSC beams were cast with and without stirrups. The beams were strengthened using NSM CFRP laminates oriented at 45-degree configuration and then tested under a three-point bending configuration. Experimental results revealed that the performance of high strength cement grout and geopolymer mortar was similar but with a lesser efficiency compared to the epoxy resin. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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20 pages, 10381 KiB  
Article
Cyclic Performance of RC Columns with Inadequate Lap Splices Strengthened with CFRP Jackets
by George Kalogeropoulos and Alexander-Dimitrios Tsonos
Fibers 2020, 8(6), 39; https://doi.org/10.3390/fib8060039 - 13 Jun 2020
Cited by 17 | Viewed by 5670
Abstract
The cyclic performance of non-seismically designed reinforced concrete (RC) columns, strengthened with carbon fiber reinforced polymer (CFRP) jackets, was analytically and experimentally investigated herein. Three cantilever column specimens were constructed, incorporating design parameters of the period 1950s–1970s, namely with concrete of a low [...] Read more.
The cyclic performance of non-seismically designed reinforced concrete (RC) columns, strengthened with carbon fiber reinforced polymer (CFRP) jackets, was analytically and experimentally investigated herein. Three cantilever column specimens were constructed, incorporating design parameters of the period 1950s–1970s, namely with concrete of a low compressive strength, plain steel bars, widely-spaced ties and inadequate lap splices of reinforcement. The specimens were strengthened using CFRP jackets and were subsequently subjected to cyclic inelastic lateral displacements. The main parameters examined were the length of the lap splices, the acceptable relative bar slipping value and the width of the jackets. The hysteresis behaviors of the enhanced columns were compared, while also being evaluated with respect to those of two original columns and to the seismic performance of a control specimen with continuous reinforcement, tested in a previous work. An analytical formulation was proposed for accurately predicting the seismic responses of the column specimens, comparing the actual shear stress value with the ultimate shear capacity of the concrete in the lap splice region. The test results verified the predictions of the analytical model, regarding the seismic performance of the strengthened columns. Moreover, the influences of the examined parameters in securing the ductile hysteresis performance were evaluated. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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13 pages, 7921 KiB  
Article
MESO-Scale Modeling of CFRP-Confined Concrete: Microplane-Based Approach
by Serena Gambarelli and Joško Ožbolt
Fibers 2020, 8(6), 38; https://doi.org/10.3390/fib8060038 - 13 Jun 2020
Cited by 4 | Viewed by 3697
Abstract
The present paper shows the results of three-dimensional (3D) meso-scale numerical simulations that were performed on unconfined and Carbon Fibre Reinforced Polymer (CFRP)-confined concrete specimens under uniaxial compression. The numerical results are compared with available experimental data. The meso-scale structure of concrete is [...] Read more.
The present paper shows the results of three-dimensional (3D) meso-scale numerical simulations that were performed on unconfined and Carbon Fibre Reinforced Polymer (CFRP)-confined concrete specimens under uniaxial compression. The numerical results are compared with available experimental data. The meso-scale structure of concrete is composed by two phases, namely: the coarse aggregate and the mortar matrix. The presence of Interfacial Transition Zone (ITZ) is neglected. A simple generation procedure is used to randomly place the coarse aggregate inside the concrete specimens. The finite element code MASA is used to perform the three-dimensional (3D) Finite Element meso-scale simulations. The constitutive laws for mortar and epoxy resin are based on the microplane model, while an elastic-brittle behavior is assumed for the fibers. Aggregate in concrete is considered to be linear elastic. The adopted meso-scale model for concrete can realistically reproduce the mechanical behavior of both unconfined and CFRP-confined specimens. However, in the case of small corner radius, the effect of confinement predicted by the model is overestimated with respect to the experimental results. This is partially related to the simplifications introduced in the model in terms of aggregate volumetric fraction (10%) and aggregate size distribution. It is shown that a more detailed meso-scale model, which is characterized by 30% of the coarse aggregate and realistic aggregate size distribution, can better capture the interaction between the concrete heterogeneity and the confining effect provided by CFRP. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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14 pages, 3595 KiB  
Article
A Comparative Study of the Performance of Slender Reinforced Concrete Columns with Different Cross-Sectional Shapes
by Safaa Qays Abdualrahman and Alaa Hussein Al-Zuhairi
Fibers 2020, 8(6), 35; https://doi.org/10.3390/fib8060035 - 4 Jun 2020
Cited by 7 | Viewed by 5000
Abstract
Most reinforced concrete (RC) structures are constructed with square/rectangular columns. The cross-section size of these types of columns is much larger than the thickness of their partitions. Therefore, parts of these columns are protruded out of the partitions. The emergence of columns edges [...] Read more.
Most reinforced concrete (RC) structures are constructed with square/rectangular columns. The cross-section size of these types of columns is much larger than the thickness of their partitions. Therefore, parts of these columns are protruded out of the partitions. The emergence of columns edges out of the walls has some disadvantages. This limitation is difficult to be overcome with square or rectangular columns. To solve this problem, new types of RC columns called specially shaped reinforced concrete (SSRC) columns have been used as hidden columns. Besides, the use of SSRC columns provides many structural and architectural advantages as compared with rectangular columns. Therefore, this study was conducted to explain the structural performance of slender SSRC columns experimentally and numerically via nonlinear finite element analysis. The study is based on nine RC specimens tested up to failure, as well as eighteen finite element (FE) models analyzed by Abaqus soft wear program. The use of SSRC columns led to increase strength by about 12% and reduce deformations, especially with slenderness ratio more than 40 as compared with equivalent square-shaped columns. Two design formulas were proposed to determine the compressive strength of SSRC columns under concentric loading. The results obtained indicate a good structural performance of SSRC columns when compared with equivalent square-shaped columns. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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16 pages, 2548 KiB  
Article
The Influence of SBS, Viatop Premium and FRP on the Improvement of Stone Mastic Asphalt Performance
by Sepehr Saedi and Seref Oruc
Fibers 2020, 8(4), 20; https://doi.org/10.3390/fib8040020 - 27 Mar 2020
Cited by 7 | Viewed by 4424
Abstract
The current study investigates the effects of Fiber Reinforce Polymer (FRP) additive on the performance of Stone Mastic Asphalt (SMA) mixtures with SBS and Viatop Premium additives. The asphalt mixture used in the current study included SBS (Styrene-Butadiene-Styrene) additive modified at the rate [...] Read more.
The current study investigates the effects of Fiber Reinforce Polymer (FRP) additive on the performance of Stone Mastic Asphalt (SMA) mixtures with SBS and Viatop Premium additives. The asphalt mixture used in the current study included SBS (Styrene-Butadiene-Styrene) additive modified at the rate of 5% according to the necessary preliminary studies, and some SMA mixture modified by adding FRP (Fiber Reinforced Polymers) additive prepared in dimensions of 5 cm in different proportions (0.3%, 0.5%, 0.7% and 0.9%). The mechanical properties of the mixtures were investigated, and the findings revealed that the SMA mixture; prepared by adding FRP additive, SBS modified bitumen, and Viatop Premium additive; increased the rutting, aging resistance and elasticity of SMAs. Moreover, load spread ability and fatigue life revealed an increase, whereas high temperature sensitivity and tendency to crack at low temperatures decreased throughout the study. The FRP contribution rate that improves the performance characteristics of the SMA mixture to the highest level was found to be 0.7%. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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22 pages, 3247 KiB  
Article
Influence of Cooling Methods on the Behavior of Reactive Powder Concrete Exposed to Fire Flame Effect
by Hadeel K. Awad
Fibers 2020, 8(3), 19; https://doi.org/10.3390/fib8030019 - 20 Mar 2020
Cited by 5 | Viewed by 3663
Abstract
The construction of highly safe and durable buildings that can bear accident damage risks including fire, earthquake, impact, and more, can be considered to be the most important goal in civil engineering technology. An experimental investigation was prepared to study the influence of [...] Read more.
The construction of highly safe and durable buildings that can bear accident damage risks including fire, earthquake, impact, and more, can be considered to be the most important goal in civil engineering technology. An experimental investigation was prepared to study the influence of adding various percentages 0%, 1.0%, and 1.5% of micro steel fiber volume fraction (Vf) to reactive powder concrete (RPC)—whose properties are compressive strength, splitting tensile strength, flexural strength, and absorbed energy—after the exposure to fire flame of various burning temperatures 300, 400, and 500 °C using gradual-, foam-, and sudden-cooling methods. The outcomes of this research proved that the maximum reduction in mechanical properties is detected in case of 0% addition at burning temperature of 500 °C using sudden cooling to be 63.90%, 55.77% and 53.8% for compressive, splitting tensile, and flexural strength, respectively, while using 1.5% produced a modification in compressive strength, splitting tensile strength, and flexural strength to 6.67%, 4.15%, and 7.00% respectively, and 7.10 kN·mm for the absorbed energy for gradual cooling at 300 °C. From the results, the adopted cooling methods can be ordered according to their negative influence by sudden, foam, and gradual, while the optimum percentage of (Vf) is 1.5% when burning at 300 °C for all methods of cooling. 1.0% is considered the optimum percentage for all burning temperatures that exceed 400 °C using sudden-cooling method. Full article
(This article belongs to the Special Issue Experimental and Numerical Advancements on Strengthening of Concrete Structures with Fiber Reinforced Polymers)
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