Submit to Polymers Review for Polymers Propose a Special Issue

Journal Browser

► Journal Browser

Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Fibers".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 12611

Share This Special Issue

Special Issue Editor

Dr. Ahmed K. El-Sayed

E-Mail Website
Guest Editor

Civil Engineering Department, King Saud University, Riyadh 11421, Saudi Arabia
Interests: structural analysis and design; FRP for reinforcing new RC structures; FRP for strengthening and upgrading existing RC structures; shear behavior of RC members; prestressed concrete
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Fiber-reinforced polymers (FRPs) have been increasingly used in the construction industry worldwide. The corrosion resistance and high strength to weight ratio are among the main features that promote the use of FRP materials in concrete structures. FRPs in the form of rods are used in reinforcing structural members in concrete buildings, bridges, parking garages, etc. FRP sheets/plates are also used for external strengthening of various members in different concrete structures. With the progress in research during the last two decades, more understanding and confidence have been acquired regarding the behavior of FRP materials as internal or external reinforcement. This Special Issue aims at collecting the most recent advances in these areas. In this Special Issue, original research articles and reviews are welcome. Research areas may include but not be limited to the following:

Flexural behavior of FRP-reinforced/-strengthened RC members;
Shear behavior of FRP-reinforced/-strengthened RC members;
FRP as longitudinal and/or transverse reinforcements in concrete compression members;
FRP for concrete confinement;
FRP-prestressed concrete;
Seismic retrofitting of RC members using FRP;
Long-term performance of FRP-reinforced/-strengthened RC members;
Analytical and numerical models for improving design practices of FRP-reinforced/-strengthened RC members.

Dr. Ahmed K. El-Sayed
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. Polymers is an international peer-reviewed open access semimonthly 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 2700 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

FRP
concrete
strengthening
debonding
fastenings/anchorages
experimental studies
design methods
numerical models
safety and reliability

Published Papers (6 papers)

Download All Papers

Research

23 pages, 3184 KiB

Open AccessArticle

Seismic Performance of Recycled Aggregate Geopolymer Concrete-Filled Double Skin Tubular Columns with Internal Steel and External FRP Tube

by Yasser Alashker and Ali Raza

Polymers 2022, 14(23), 5204; https://doi.org/10.3390/polym14235204 - 29 Nov 2022

Cited by 2 | Viewed by 1298

Abstract

The large production of cement is resulting in a high-carbon footprint, which is essential to minimize for sustainable concrete construction. Moreover, the large quantity of recycled coarse aggregate (RCA) from the demolition of old concrete structures is creating problems for landfill and disposal. The primary goal of this study is to investigate the seismic efficiency of innovative fiber-reinforced polymer (FRP)-recycled aggregate geopolymer concrete (RAGC) steel-tubed columns (FGSTCs) with an internal steel tube (STT), an external glass-FRP tube (GLT), and RAGC located between the two-tubed components to develop a serviceable structural element. To study their seismic functioning under axial load and lateral repeated load, five FGSTC specimens were manufactured and analyzed under quasi-static loads. The influence of three variables on the performance of FGSTC specimens, consisting of STT reinforcing ratio, compression ratio, and recycled coarse aggregate (RCA) replacement ratio, was investigated in this investigation. The produced specimens’ ductility, hysteretic loops, strain distribution, skeleton curves, stiffness functioning, energy capacity dissipation, damaging functioning, and strength loss were all assessed and discussed. The results of this investigation revealed that percentage substitution of RCA had a minor impact on the seismic functioning of FGSTCs; however, the compression-load ratio depicted a substantial impact. The energy loss of the FGSTCs was 24.5% higher than that of their natural aggregate equivalents. FGSTCs may have a 16.9% lower cumulative failure rate than their natural aggregate counterparts. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures

Figure 1

17 pages, 3447 KiB

Open AccessArticle

Low-Cost Fiber Chopped Strand Mat Composites for Compressive Stress and Strain Enhancement of Concrete Made with Brick Waste Aggregates

by Panuwat Joyklad, Panumas Saingam, Nazam Ali, Ali Ejaz, Qudeer Hussain, Kaffayatullah Khan and Krisada Chaiyasarn

Polymers 2022, 14(21), 4714; https://doi.org/10.3390/polym14214714 - 03 Nov 2022

Cited by 13 | Viewed by 1728

Abstract

Given the excessive demolition of structures each year, the issues related to the generated structural waste are striking. Bricks being a major constituent in the construction industry, also hold a significant proportion of the construction waste generated annually. The reuse of this brick waste in new constructions is an optimal solution considering cost-effectiveness and sustainability. However, the problems related to the substandard peak stress and ultimate strain of concrete constructed with recycled brick aggregates (CRAs) limit its use in non-structural applications. The present study intends to improve the unsatisfactory mechanical characteristics of CRAs by utilizing low-cost glass fiber chopped strand mat (FCSM) sheets. The efficacy of FCSM sheets was assessed by wrapping them around CRA specimens constructed with different concrete strengths. A remarkable increase in the peak compressive stress and the ultimate strain of the CRA specimens were observed. For low, medium, and high strength CRAs, the ultimate strain improved by up to 320%, 308%, and 294%, respectively, as compared to the respective control specimens. Several existing analytical models were utilized to predict the peak compressive stress and ultimate strain of the CRAs strengthened using FCSM sheets. None of the considered models reproduced experimental results accurately. Therefore, equations were formulated using regression predicting the peak stress and ultimate strain of the CRAs confined with FCSM sheets. The predicted values were found to correlate well with the experimental values. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures

Figure 1

23 pages, 5920 KiB

Open AccessArticle

Finite Element Modeling of Debonding Failures in FRP-Strengthened Concrete Beams Using Cohesive Zone Model

by Mohammed A. Al-Saawani, Abdulaziz I. Al-Negheimish, Ahmed K. El-Sayed and Abdulrahman M. Alhozaimy

Polymers 2022, 14(9), 1889; https://doi.org/10.3390/polym14091889 - 05 May 2022

Cited by 10 | Viewed by 2433

Abstract

Intermediate crack (IC) debonding and concrete cover separation (CCS) are common types of debonding failures in concrete beams flexurally strengthened with fiber-reinforced polymer (FRP) composites. In this paper, a three-dimensional finite element (FE) model was developed to simulate the flexural behavior and predict the critical debonding failure in FRP-strengthened beams. The two critical debonding failures were considered in the FE model by implementing a cohesive zone model based on fracture mechanics considering the effect of the related parameters. The input values used for the cohesive zone model are modified in this study to obtain accurate and consistent predictions. The FE model was validated by comparison with experimental results tested by the authors for beams particularly prone to fail by either of the two critical debonding failures. The results obtained from the FE model agree well with the experimental results for both of the debonding failures and the corresponding capacities at failure. In general, the ratio of the experimental to numerical ultimate capacities was within 5%, and so was the ratio of the experimental to numerical mid-span deflections at debonding failures. The FE model developed in this study was then used to conduct a parametric study investigating the effect of shear span-to-depth ratio and spacing of steel stirrups on the ultimate capacity and type of debonding failure in FRP-strengthened beams. The results of the parametric study revealed that increasing the spacing of steel stirrups caused a significant decrease in the load capacity at concrete cover separation failure. In addition, varying the shear span-to-depth ratio was seen to have an important effect on the type of debonding failure and corresponding capacities for the FRP-strengthened beams having the same cross-section geometry and CFRP reinforcement. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures

Figure 1

24 pages, 5933 KiB

Open AccessArticle

Punching Shear Strength of FRP-Reinforced Concrete Slabs without Shear Reinforcements: A Reliability Assessment

by Soliman Alkhatib and Ahmed Deifalla

Polymers 2022, 14(9), 1743; https://doi.org/10.3390/polym14091743 - 25 Apr 2022

Cited by 13 | Viewed by 2162

Abstract

The recent failure of buildings because of punching shear has alerted researchers to assess the reliability of the punching shear design models. However, most of the current research studies focus on model uncertainty compared to experimentally measured strength, while very limited studies consider the variability of the basic variables included in the model and the experimental measurements. This paper discusses the reliability of FRP-reinforced concrete slabs’ existing punching shear models. First, more than 180 specimens were gathered. Second, available design codes and simplified models were selected and used in the calculation. Third, several reliability methods were conducted; therefore, three methods were implemented, including the mean-value first-order second moment (MVFOSM) method, the first-order second moment (FOSM) method, and the second-order reliability method (SORM). A comparison between the three methods showed that the reliability index calculated using the FOSM is quite similar to that using SORM. However, FOSM is simpler than SORM. Finally, the reliability and sensitivity of the existing strength models were assessed. At the same design point, the reliability index varied significantly. For example, the most reliable was the JSCE, with a reliability index value of 4.78, while the Elgendy-a was the least reliable, with a reliability index of 1.03. The model accuracy is the most significant parameter compared to other parameters, where the sensitivity factor varied between 67% and 80%. On the other hand, the column dimension and flexure reinforcement are the least significant parameters compared to other parameters where the sensitivity factor was 0.4% and 0.3%, respectively. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures

Figure 1

25 pages, 2183 KiB

Open AccessArticle

Evaluation of the Strength of Slab-Column Connections with FRPs Using Machine Learning Algorithms

by Nermin M. Salem and Ahmed Deifalla

Polymers 2022, 14(8), 1517; https://doi.org/10.3390/polym14081517 - 08 Apr 2022

Cited by 31 | Viewed by 1720

Abstract

Slab-column connections with FRPs fail suddenly without warning. Machine learning (ML) models can model the behavior with high precision and reliability. Nineteen ML algorithms were examined and compared. The comparisons showed that the ensembled boosted tree model showed the best, most precise prediction with the highest coefficient of determination (R²) (0.98), the lowest Root Mean Square Error (RMSE) (44.12 kN), and the lowest Mean Absolute Error (MAE) (35.95 kN). The ensembled boosted model had an average of 0.99, a coefficient of variation of 12%, and a lower 95% of 0.97, respectively, in terms of the measured strength. Thus, it was found to be more accurate and consistent compared to all implemented machine learning models and selected traditional models. In addition, the significance of various parameters with respect to the predicted strength was identified, where the effective depth was the most significant by a factor of 0.9, and the concrete compressive strength was the lowest by a factor of 0.3. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures

Figure 1

31 pages, 14248 KiB

Open AccessArticle

Ductility Estimation for Flexural Concrete Beams Longitudinally Reinforced with Hybrid FRP–Steel Bars

by Rendy Thamrin, Zaidir Zaidir and Devitasari Iwanda

Polymers 2022, 14(5), 1017; https://doi.org/10.3390/polym14051017 - 03 Mar 2022

Cited by 9 | Viewed by 2595

Abstract

An experimental study was conducted to evaluate the ductility of reinforced concrete beams longitudinally reinforced with hybrid Fiber Reinforced Polymer (FRP)–steel bars. The specimens were fourteen reinforced concrete beams with and without hybrid reinforcement. The test variables were bar positions, ratio of longitudinal reinforcement, and type of FRP. The beams were loaded until failure using a four-point bending test. The performance of the tested beams was observed using the load–deflection curve obtained from the test. Numerical analysis using the fiber element model was carried out to examine the growth of neutral axis due to the effects of the test variables. The neutral axis curves were then used to estimate the neutral axis angles and displacement indices. The test results showed that the reinforcement position did not significantly affect the flexural capacity of beams with a higher ratio of hybrid reinforcement, but was quite significant in beams with a lower ratio of hybrid reinforcement. It was observed from the test that the flexural capacity of beams with hybrid reinforcement was 15–45% higher than that of beams with conventional steel bars, depending on bar positions and the ratio of longitudinal reinforcement. The ductility of beams with hybrid reinforcement was significantly increased compared to that of beams with FRP, but decreased as the hybrid reinforcement ratio (A_f/A_s) increased. This study also showed that the developed numerical model could predict the flexural behavior of beams with hybrid reinforcement with reasonable accuracy. Based on the test results, parametric analysis, and data obtained from the literature, the use of the neutral axis angle and displacement index value to evaluate the ductility of cross-sections with hybrid reinforcement is proposed. Full article

(This article belongs to the Special Issue Advance and Progress of Fiber-Reinforced Polymers in Reinforcing and Strengthening Concrete Structures)

► Show Figures