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Special Issue "Fiber-Reinforced Polymer Composites in Structural Engineering"

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A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (30 April 2014)

Special Issue Editors

Guest Editor
Prof. Dr. Alper Ilki

Structural and Earthquake Engineering Laboratory, Civil Engineering Faculty, Istanbul Technical University, 34469 Maslak Istanbul, Turkey
Website | E-Mail
Phone: + 90 212 285 3838 (office)
Fax: + 90 212 285 3838
Interests: structural engineering; reinforced concrete structures; masonry structures; seismic retrofit with advanced materials; seismic performance assessment
Guest Editor
Prof. Dr. Masoud Motavalli

Empa, Structural Engineering Research Laboratory, Überlandstrasse 129, 8600 Dübendorf, Switzerland
Website | E-Mail
Phone: +41 58 765 4116
Interests: application of advanced materials (such as fiber-reinforced polymer composites and shape memory alloys in civil engineering); structural rehabilitation and repair; seismic retrofitting; large and full scale laboratory and field experiments

Special Issue Information

Dear Colleagues,

This special issue of Polymers Journal is dedicated to Fiber-Reinforced Polymer (FRP) Composites in Structural Engineering. We are expecting to receive papers dealing with cutting-edge issues on research and application of FRP composites in structural engineering. The topics of the special issue includes but not limited to: Seismic Retrofitting using FRP composites, Confinement of concrete columns using FRP composites, Strengthening of masonry and historical structures using FRP composites, External strengthening of concrete, timber and steel structures using FRP composites, Near surface mounting reinforcement using FRP composites, Durability issues of FRP strengthened structures, Fire protection systems for FRP strengthened structures, Practical applications and case studies, Internally reinforced concrete (with FRP rebars), All composite structures using FRP profiles, plates and shells, Testing and characterisation of FRP elements for structural engineering, Health monitoring of FRP structures.

Prof. Dr. Alper Ilki
Prof. Dr. Masoud Motavalli
Guest Edito
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Submission

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. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as 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 refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers 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 1400 CHF (Swiss Francs).


Keywords

  • FRP composites
  • seismic retrofitting
  • external strengthening
  • structural rehabilitation
  • durability
  • fire protection systems
  • NSMR using FRP
  • FRP reinforced concrete
  • FRP profiles
  • testing
  • structural health monitoring

Published Papers (16 papers)

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Research

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Open AccessArticle Long-Term Bending Creep Behavior of Thin-Walled CFRP Tendon Pretensioned Spun Concrete Poles
Polymers 2014, 6(7), 2065-2081; doi:10.3390/polym6072065
Received: 5 May 2014 / Revised: 3 July 2014 / Accepted: 16 July 2014 / Published: 23 July 2014
Cited by 1 | PDF Full-text (1835 KB) | HTML Full-text | XML Full-text
Abstract
This paper discusses the long-term behavior of a series of highly-loaded, spun concrete pole specimens prestressed with carbon fiber-reinforced polymer (CFRP) tendons, which were subjected to outdoor four-point bending creep tests since 1996 in the frame of collaboration with the Swiss precast concrete
[...] Read more.
This paper discusses the long-term behavior of a series of highly-loaded, spun concrete pole specimens prestressed with carbon fiber-reinforced polymer (CFRP) tendons, which were subjected to outdoor four-point bending creep tests since 1996 in the frame of collaboration with the Swiss precast concrete producer, SACAC (Società Anonima Cementi Armati Centrifugati). The 2 m span cylindrical beams studied are models for lighting poles produced for the last 10 years and sold on the European market. Five thin-walled pole specimens were investigated (diameter: 100 mm; wall-thickness: 25–27 mm). All specimens were produced in a pretensioning and spinning technique and were prestressed by pultruded CFRP tendons. Initially, two reference pole specimens were tested in quasi-static four-point bending to determine the short-term failure moment and to model the short-term flexural behavior. Then, three pole specimens were loaded to different bending creep moments: while the lowest loaded specimen was initially uncracked, the second specimen was loaded with 50% of the short-term bending failure moment and exhibited cracking immediately after load introduction. The highest loaded pole specimen sustained a bending moment of 72% of the short-term bending failure moment for 16.5 years before failing in July 2013, due to the bond failure of the tendons, which led to local crushing of the high-performance spun concrete (HPSC). Besides this, long-term monitoring of the creep tests has shown a limited time- and temperature-dependent increase of the deflections over the years, mainly due to the creep of the concrete. A concrete creep-based model allowed for the calculation of the long-term bending curvatures with reasonable accuracy. Furthermore, the pole specimens showed crack patterns that were stable over time and minimal slippage of the tendons with respect to the pole’s end-faces for the two lower load levels. The latter proves the successful and durable anchorage of these novel CFRP prestressing tendons in thin-walled, precast concrete members under realistic long-term service loads. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle FRP-RC Beam in Shear: Mechanical Model and Assessment Procedure for Pseudo-Ductile Behavior
Polymers 2014, 6(7), 2051-2064; doi:10.3390/polym6072051
Received: 13 May 2014 / Revised: 26 June 2014 / Accepted: 1 July 2014 / Published: 18 July 2014
Cited by 1 | PDF Full-text (862 KB) | HTML Full-text | XML Full-text
Abstract
This work deals with the development of a mechanics-based shear model for reinforced concrete (RC) elements strengthened in shear with fiber-reinforced polymer (FRP) and a design/assessment procedure capable of predicting the failure sequence of resisting elements: the yielding of existing transverse steel ties
[...] Read more.
This work deals with the development of a mechanics-based shear model for reinforced concrete (RC) elements strengthened in shear with fiber-reinforced polymer (FRP) and a design/assessment procedure capable of predicting the failure sequence of resisting elements: the yielding of existing transverse steel ties and the debonding of FRP sheets/strips, while checking the corresponding compressive stress in concrete. The research aims at the definition of an accurate capacity equation, consistent with the requirement of the pseudo-ductile shear behavior of structural elements, that is, transverse steel ties yield before FRP debonding and concrete crushing. For the purpose of validating the proposed model, an extended parametric study and a comparison against experimental results have been conducted: it is proven that the common accepted rule of assuming the shear capacity of RC members strengthened in shear with FRP as the sum of the maximum contribution of both FRP and stirrups can lead to an unsafe overestimation of the shear capacity. This issue has been pointed out by some authors, when comparing experimental shear capacity values with the theoretical ones, but without giving a convincing explanation of that. In this sense, the proposed model represents also a valid instrument to better understand the mechanical behavior of FRP-RC beams in shear and to calculate their actual shear capacity. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
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Open AccessArticle On the Use of CFRP Sheets for the Seismic Retrofitting of Masonry Walls and the Influence of Mechanical Anchorage
Polymers 2014, 6(7), 1972-1998; doi:10.3390/polym6071972
Received: 9 April 2014 / Revised: 25 June 2014 / Accepted: 1 July 2014 / Published: 10 July 2014
Cited by 1 | PDF Full-text (3480 KB) | HTML Full-text | XML Full-text
Abstract
This work reports the outcomes of an extensive experimental campaign on the retrofitting of masonry walls by means of carbon fiber reinforced polymer (CFRP) sheets, carried out at University of Applied Sciences (UAS) Fribourg. In the first stage, static-cyclic shear tests were conducted
[...] Read more.
This work reports the outcomes of an extensive experimental campaign on the retrofitting of masonry walls by means of carbon fiber reinforced polymer (CFRP) sheets, carried out at University of Applied Sciences (UAS) Fribourg. In the first stage, static-cyclic shear tests were conducted on the masonry walls, followed by a second stage of tensile tests on alternative configurations of mechanical anchorage so as to assess the effects on the structural response and to identify the associated limits. In the static-cyclic shear tests, it was found that the resistance of masonry walls retrofitted with CFRP sheets was improved by up to 70%, and the deformability was improved by up to 10% in comparison to the un-retrofitted specimens. The experimental tests conducted on alternate configurations of mechanical anchorages indicate that the tested materials and configurations rely heavily on details. The sensitivity of CFRP sheets to edges, non-uniformities on any adherend, and bonding defects can cause premature CFRP failure and, hence, pose problems for the efficient design of a retrofitting scheme. As indicated by the results of this investigation, effective anchorage can be achieved when eccentric loading of the mechanical anchorage is avoided and a smooth bonding surface is guaranteed. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Mechanical Behavior of BFRP-Steel Composite Plate under Axial Tension
Polymers 2014, 6(6), 1862-1876; doi:10.3390/polym6061862
Received: 8 April 2014 / Revised: 28 May 2014 / Accepted: 12 June 2014 / Published: 23 June 2014
Cited by 2 | PDF Full-text (749 KB) | HTML Full-text | XML Full-text
Abstract
Combining the advantages of basalt fiber-reinforced polymer (BFRP) material and steel material, a novel BFRP-steel composite plate (BSP) is proposed, where a steel plate is sandwiched between two outer BFRP laminates. The main purpose of this research is to investigate the mechanical behavior
[...] Read more.
Combining the advantages of basalt fiber-reinforced polymer (BFRP) material and steel material, a novel BFRP-steel composite plate (BSP) is proposed, where a steel plate is sandwiched between two outer BFRP laminates. The main purpose of this research is to investigate the mechanical behavior of the proposed BSP under uniaxial tension and cyclic tension. Four groups of BSP specimens with four different BFRP layers and one control group of steel plate specimens were prepared. A uniaxial tensile test and a cyclic tensile test were conducted to determine the initial elastic modulus, postyield stiffness, yield strength, ultimate bearing capacity and residual deformation. Test results indicated that the stress-strain curve of the BSP specimen was bilinear prior to the fracture of the outer BFRP, and the BSP specimen had stable postyield stiffness and small residual deformation after the yielding of the inner steel plate. The postyield modulus of BSP specimens increased almost linearly with the increasing number of outer BFRP layers, as well as the ultimate bearing capacity. Moreover, the predicted results from the selected models under both monotonic tension and cyclic tension were in good agreement with the experimental data. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
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Open AccessArticle Long-Term Flexural Behaviors of GFRP Reinforced Concrete Beams Exposed to Accelerated Aging Exposure Conditions
Polymers 2014, 6(6), 1773-1793; doi:10.3390/polym6061773
Received: 19 April 2014 / Revised: 3 June 2014 / Accepted: 5 June 2014 / Published: 16 June 2014
Cited by 4 | PDF Full-text (1528 KB) | HTML Full-text | XML Full-text
Abstract
This study investigates the impact of accelerated aging conditions on the long-term flexural behavior and ductility of reinforced concrete (RC) members with glass fiber-reinforced polymer (GFRP) bars (RC-GFRP specimen) and steel bars (RC-steel specimen). A total of thirty six specimens were designed with
[...] Read more.
This study investigates the impact of accelerated aging conditions on the long-term flexural behavior and ductility of reinforced concrete (RC) members with glass fiber-reinforced polymer (GFRP) bars (RC-GFRP specimen) and steel bars (RC-steel specimen). A total of thirty six specimens were designed with different amounts of reinforcement with three types of reinforcing bars (i.e., helically wrapped GFRP, sand-coated surface GFRP and steel). Eighteen specimens were subjected to sustained loads and accelerated aging conditions (i.e., 47 °C and 80% relative humidity) in a chamber. The flexural behavior of specimens under 300-day exposure was compared to that of the companion specimens without experiencing accelerated aging conditions. Results indicate that the accelerated aging conditions reduced flexural capacity in not only RC-steel, but also RC-GFRP specimens, with different rates of reduction. Different types of GFRP reinforcement exhibited different rates of degradation of the flexural capacity when embedded in concrete under the same exposure conditions. Several existing models were compared with experimental results for predicting the deflection and deformability index for specimens. Bischoff and Gross’s model exhibited an excellent prediction of the time-dependent deflections. Except for the deformability index proposed by Jaeger, there was no general trend related to the aging duration. This study recommends the need for further investigation on the prediction of the deformability index. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle The Effect of CFRP Length on the Failure Mode of Strengthened Concrete Beams
Polymers 2014, 6(6), 1705-1726; doi:10.3390/polym6061705
Received: 9 April 2014 / Revised: 30 May 2014 / Accepted: 3 June 2014 / Published: 10 June 2014
Cited by 1 | PDF Full-text (1346 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports the effects of carbon fiber-reinforced polymer (CFRP) length on the failure process, pattern and crack propagation for a strengthened concrete beam with an initial notch. The experiments measuring load-bearing capacity for concrete beams with various CFRP lengths have been performed,
[...] Read more.
This paper reports the effects of carbon fiber-reinforced polymer (CFRP) length on the failure process, pattern and crack propagation for a strengthened concrete beam with an initial notch. The experiments measuring load-bearing capacity for concrete beams with various CFRP lengths have been performed, wherein the crack opening displacements (COD) at the initial notch are also measured. The application of CFRP can significantly improve the load-bearing capacity, and the failure modes seem different with various CFRP lengths. The stress profiles in the concrete material around the crack tip, at the end of CFRP and at the interface between the concrete and CFRP are then calculated using the finite element method. The experiment measurements are validated by theoretical derivation and also support the finite element analysis. The results show that CFRP can significantly increase the ultimate load of the beam, while such an increase stops as the length reaches 0.15 m. It is also concluded that the CFRP length can influence the stress distribution at three critical stress regions for strengthened concrete beams. However, the optimum CFRP lengths vary with different critical stress regions. For the region around the crack tip, it is 0.15 m; for the region at the interface it is 0.25 m, and for the region at the end of CFRP, it is 0.30 m. In conclusion, the optimum CFRP length in this work is 0.30 m, at which CFRP strengthening is fully functioning, which thus provides a good reference for the retrofitting of buildings. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle The Effects of Loading Rate and Duration on the Axial Behavior of Low-Strength and Medium-Strength Noncircular Concrete Members Confined by Fiber-Reinforced Polymer Sheets
Polymers 2014, 6(6), 1685-1704; doi:10.3390/polym6061685
Received: 8 May 2014 / Revised: 28 May 2014 / Accepted: 29 May 2014 / Published: 6 June 2014
Cited by 2 | PDF Full-text (1629 KB) | HTML Full-text | XML Full-text
Abstract
In this study, 36 concrete specimens with square cross-sections and different concrete qualities were tested either under uniaxial compression at different loading rates or subjected to sustained uniaxial stresses after externally jacketing with carbon fiber-reinforced polymer (CFRP) sheets. The main test parameters were
[...] Read more.
In this study, 36 concrete specimens with square cross-sections and different concrete qualities were tested either under uniaxial compression at different loading rates or subjected to sustained uniaxial stresses after externally jacketing with carbon fiber-reinforced polymer (CFRP) sheets. The main test parameters were the loading rate and the applied sustained stress level. Among these parameters, the loading rate varied in the range of 0.0002 and 0.04 strain/min. In the case of short-term creep tests under sustained loads, three stress levels (between 0.73 f'cc and 0.90 f'cc or 2.76 f'cc and 3.37 f'cc) for low-strength and four stress levels (between 0.69 f'cc and 0.92 f'cc or 0.89 f'co and 1.20 f'co) for medium-strength prisms were applied. The test results showed that the stress-strain behavior of CFRP-confined concrete was affected by the change in loading rate, and external CFRP confinement enhanced the creep performance of concrete significantly. For low-strength concrete specimens, higher strain rates did not bring higher strength values; however, an increase in strength was obvious for medium-strength prisms. On the other hand, for both concrete qualities, the specimens loaded at slower strain rates exhibited better deformability. None of the specimens of the medium-strength concrete failed during the short-term creep tests; however, three of the low-strength concrete prisms failed during the tests. The results of residual strength tests showed that sustained loading did not cause a strength or ultimate deformation capacity loss, but affected the residual strain capacities. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Effect of Shear Resistance on Flexural Debonding Load-Carrying Capacity of RC Beams Strengthened with Externally Bonded FRP Composites
Polymers 2014, 6(5), 1366-1380; doi:10.3390/polym6051366
Received: 8 February 2014 / Revised: 29 April 2014 / Accepted: 4 May 2014 / Published: 13 May 2014
PDF Full-text (1890 KB) | HTML Full-text | XML Full-text
Abstract
Debonding failure is the main failure mode in flexurally strengthened reinforced concrete beams by externally bonded or near surface mounted fibre reinforced polymer (FRP) composites. It is believed that FRP debonding will be initiated if the shear stress on the concrete-FRP interface reaches
[...] Read more.
Debonding failure is the main failure mode in flexurally strengthened reinforced concrete beams by externally bonded or near surface mounted fibre reinforced polymer (FRP) composites. It is believed that FRP debonding will be initiated if the shear stress on the concrete-FRP interface reaches the tensile strength of concrete. However, it was found through experimental and analytical studies that the debonding mechanism of FRP composites has the potential of shear failure in combination with debonding failure. Moreover, the shear failure probably influences the debonding failure. Presently, there are very little experimental and analytical studies to investigate the influence of shear resistance of reinforced concrete (RC) beam on FRP debonding failure. The current study investigates and analyzes the effect of shear resistance on FRP debonding failure based on test results. The analytical results show that the shear resistance of RC beam has a great effect on flexural debonding load-carrying capacity of FRP-strengthened RC beam. The influence of shear resistance on flexural debonding load-carrying capacity must be fully considered in flexural strengthening design of RC beams. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Behavior of FRP-Confined Concrete-Filled Steel Tube Columns
Polymers 2014, 6(5), 1333-1349; doi:10.3390/polym6051333
Received: 30 March 2014 / Revised: 1 May 2014 / Accepted: 5 May 2014 / Published: 8 May 2014
Cited by 2 | PDF Full-text (1432 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the results of an experimental study into the behavior of concrete-filled steel tube columns confined by fiber-reinforced polymer (FRP). Eleven columns were tested to investigate the effects of the FRP layer number, the thickness of the steel tube and concrete
[...] Read more.
This paper presents the results of an experimental study into the behavior of concrete-filled steel tube columns confined by fiber-reinforced polymer (FRP). Eleven columns were tested to investigate the effects of the FRP layer number, the thickness of the steel tube and concrete strength on their load capacity and axial deformation capacity. The experimental results indicated that the FRP wrap can effectively confine the concrete expansion and delay the local buckling of the steel tube. Both the load capacity and the axial deformation capacity of concrete-filled steel tube columns can be substantially enhanced with FRP confinement. A model is proposed to predict the load capacity of the FRP-confined concrete-filled steel tube columns. The predicted results are generally in good agreement with the experimental ones obtained in this study and in the literature. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Mechanical Analysis of Stress Distribution in a Carbon Fiber-Reinforced Polymer Rod Bonding Anchor
Polymers 2014, 6(4), 1129-1143; doi:10.3390/polym6041129
Received: 27 December 2013 / Revised: 1 April 2014 / Accepted: 3 April 2014 / Published: 11 April 2014
PDF Full-text (1071 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an elastic shear stress distribution theoretical model at the carbon fiber-reinforced polymer (CFRP)-adhesive interface of a single-rod and a multi-rod straight-pipe bonding anchor. A comparison between theoretical and finite element analysis results reveals that the accuracy of the theory can
[...] Read more.
This paper presents an elastic shear stress distribution theoretical model at the carbon fiber-reinforced polymer (CFRP)-adhesive interface of a single-rod and a multi-rod straight-pipe bonding anchor. A comparison between theoretical and finite element analysis results reveals that the accuracy of the theory can be used to guide the preliminary design of CFRP rod bonding anchors. The mechanical performance of the inner cone bonding anchor for multi-rods are evaluated within different coefficients of friction and inner inclined angles. Numerical results indicate that the straight-parabolic inner cone bonding anchor has a significant effect on reducing the shear force at the loading end. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
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Open AccessArticle Strain Rate Effects in CFRP Used For Blast Mitigation
Polymers 2014, 6(4), 1026-1039; doi:10.3390/polym6041026
Received: 12 February 2014 / Revised: 17 March 2014 / Accepted: 25 March 2014 / Published: 3 April 2014
Cited by 4 | PDF Full-text (905 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of this research is to gain a better understanding of strain rate effects in carbon fiber reinforced polymer (CFRP) laminates exposed to blast loading. The use of CFRP offers an attractive option for mitigating structures exposed to blasts. However, the effect
[...] Read more.
The purpose of this research is to gain a better understanding of strain rate effects in carbon fiber reinforced polymer (CFRP) laminates exposed to blast loading. The use of CFRP offers an attractive option for mitigating structures exposed to blasts. However, the effect of high strain rates in CFRP composites commonly used in the civil industry is unknown. This research conducted tensile tests of 21 CFRP coupons using a hydraulically powered dynamic loader. The strain rates ranged from 0.0015 s−1 to 7.86 s−1 and are representative of strain rates that CFRP may see in a blast when used to strengthen reinforced concrete structures. The results of the testing showed no increase in the tensile strength or stiffness of the CFRP at the higher strain rates. In addition, the results showed significant scatter in the tensile strengths possibly due to the rate of loading or manufacture of the coupon. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Flexural Behavior of RC Members Using Externally Bonded Aluminum-Glass Fiber Composite Beams
Polymers 2014, 6(3), 667-685; doi:10.3390/polym6030667
Received: 25 December 2013 / Revised: 26 February 2014 / Accepted: 3 March 2014 / Published: 10 March 2014
Cited by 1 | PDF Full-text (768 KB) | HTML Full-text | XML Full-text
Abstract
This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC) beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point
[...] Read more.
This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC) beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-sectional shape of the AGC beam, the glass fiber fabric array, and the installation of fasteners. The load-deflection response, strain distribution along the longitudinal axis of the beam, and associated failure modes of the tested specimens were recorded. It was observed that the AGC beam led to an increase of the initial cracking load, yielding load of the tension steels and peak load. On the other hand, the ductility of some specimens strengthened was reduced by more than 50%. The A-type AGC beam was more efficient in slab specimens than in beam specimens and the B-type was more suitable for beam specimens than for slabs. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Statistical Analysis of the Progressive Failure Behavior for Fiber-Reinforced Polymer Composites under Tensile Loading
Polymers 2014, 6(1), 145-159; doi:10.3390/polym6010145
Received: 11 November 2013 / Revised: 31 December 2013 / Accepted: 8 January 2014 / Published: 10 January 2014
Cited by 2 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
An analytical approach with the help of numerical simulations based on the equivalent constraint model (ECM) was proposed to investigate the progressive failure behavior of symmetric fiber-reinforced composite laminates damaged by transverse ply cracking. A fracture criterion was developed to describe the initiation
[...] Read more.
An analytical approach with the help of numerical simulations based on the equivalent constraint model (ECM) was proposed to investigate the progressive failure behavior of symmetric fiber-reinforced composite laminates damaged by transverse ply cracking. A fracture criterion was developed to describe the initiation and propagation of the transverse ply cracking. This work was also concerned with a statistical distributions of the critical fracture toughness values with due consideration given to the scale size effect. The Monte Carlo simulation technique coupled with statistical analysis was applied to study the progressive cracking behaviors of composite structures, by considering the effects of lamina properties and lay-up configurations. The results deduced from the numerical procedure were in good agreement with the experimental results obtained for laminated composites formed by unidirectional fiber reinforced laminae with different orientations. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
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Open AccessArticle Cohesive Fracture Study of a Bonded Coarse Silica Sand Aggregate Bond Interface Subjected to Mixed-Mode Bending Conditions
Polymers 2014, 6(1), 12-38; doi:10.3390/polym6010012
Received: 28 October 2013 / Revised: 26 November 2013 / Accepted: 3 December 2013 / Published: 23 December 2013
PDF Full-text (2468 KB) | HTML Full-text | XML Full-text
Abstract
One of the primary objectives in the design of composite structures is the prevention of premature bond failure. Therefore, the characterization of cohesive behavior is an important field of study in structural engineering. Using fracture mechanics principles, the cohesive behavior of an epoxy
[...] Read more.
One of the primary objectives in the design of composite structures is the prevention of premature bond failure. Therefore, the characterization of cohesive behavior is an important field of study in structural engineering. Using fracture mechanics principles, the cohesive behavior of an epoxy bonded coarse silica sand aggregate bond interface is studied in this paper, with a focus on finding a general analytical form of idealizing its behavior when used in a specimen possessing asymmetric and inhomogeneous qualities. Two series of small-scale specimens were experimentally tested under mixed-mode bending (MMB) conditions, where it was found that there was negligible influence exerted on the fracture energy of the interface due to changes in the mixed-mode ratio or initial crack length. Using finite element analysis (FEA) methods, an appropriate bilinear traction-separation model was developed to both validate as well as obtain a set of consistent parameters applicable to all tested specimens. Comparison of the Global Method and the Local Method, used to obtain partitioned Mode I and Mode II fracture energy values from MMB specimens, were made, with the conclusion that both methods are adequate in the calculation of the total fracture energy though the Local Method should be used to obtain accurate partitioned Mode I and Mode II fracture energy values. Idealization of the bond interface using the cohesive parameters derived can be accurately achieved by the use of both contact interactions and cohesive elements in two-dimensional and three-dimensional FE models, though the results obtained using contact interactions would be expected to exhibit greater global stiffness. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)
Open AccessArticle Strengthening of RC Slabs with Symmetric Openings Using GFRP Composite Beams
Polymers 2013, 5(4), 1352-1361; doi:10.3390/polym5041352
Received: 28 October 2013 / Revised: 25 November 2013 / Accepted: 27 November 2013 / Published: 3 December 2013
Cited by 2 | PDF Full-text (627 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the results of experimental testing of glass fiber reinforced plastic (GFRP) composite beam strengthened reinforced concrete (RC) slabs with two symmetrical openings. Specimens, one-half scale, have been designed and fabricated to reflect the most common RC bathroom slab used in
[...] Read more.
This paper describes the results of experimental testing of glass fiber reinforced plastic (GFRP) composite beam strengthened reinforced concrete (RC) slabs with two symmetrical openings. Specimens, one-half scale, have been designed and fabricated to reflect the most common RC bathroom slab used in school buildings. The specimen had dimensions of 2000 mm (width) × 150 mm (thickness) × 3000 mm (length) were used with the two openings of 300 mm × 400 mm. The aim of this study is to investigate the most effective strengthening method using GFRP composite beams in slabs with openings for enhancing the load-carrying capacity and stiffness. Test results showed that the strengthened slabs seems to increase the load-carrying capacity by 29%, 21% and 12% over that of the control specimen for diagonal, parallel and surround strengthening respectively. Furthermore, test results showed that the diagonal-strengthened system is one of the most effective methods for strengthening an RC slab with openings in terms of load-carrying capacity, stiffness and crack patterns. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)

Review

Jump to: Research

Open AccessReview A Critical Review of Research on Reuse of Mechanically Recycled FRP Production and End-of-Life Waste for Construction
Polymers 2014, 6(6), 1810-1826; doi:10.3390/polym6061810
Received: 25 April 2014 / Revised: 28 May 2014 / Accepted: 4 June 2014 / Published: 17 June 2014
Cited by 7 | PDF Full-text (1464 KB) | HTML Full-text | XML Full-text
Abstract
For the last three decades, fiber reinforced polymer (FRP) composite materials have been widely used in major engineering industries. Managing FRP waste is becoming an important issue due to the growth in the production of FRP composite materials. In this article, the issue
[...] Read more.
For the last three decades, fiber reinforced polymer (FRP) composite materials have been widely used in major engineering industries. Managing FRP waste is becoming an important issue due to the growth in the production of FRP composite materials. In this article, the issue of FRP waste management is discussed and the commonly used methods for the handling of FRP waste are reviewed. One potentially viable use of FRP waste is in the partial replacement of fillers or aggregates in cementitious materials (particularly portland cement mortar and concrete). A number of important prior investigations performed on the use of FRP waste in concrete and mortar are reviewed. The results from most of those investigations suggest that FRP aggregates significantly reduce the strength of cementitious materials with little significant effect on durability. Recommendations for future research in this area are provided for producing stronger mortars and concretes incorporating FRP production and end-of-life waste. Full article
(This article belongs to the Special Issue Fiber-Reinforced Polymer Composites in Structural Engineering)

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