Editorial

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3 pages, 157 KiB

Open AccessEditorial

Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering

by Jianzhe Shi

Buildings 2023, 13(7), 1755; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings13071755 - 10 Jul 2023

Cited by 1 | Viewed by 850

Abstract

Concrete has become one of the most widely used structural materials in civil engineering [...] Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

Research

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16 pages, 4483 KiB

Open AccessArticle

Tensile Mechanical and Stress-Strain Behavior of Recycling Polypropylene Fiber Recycled Coarse Aggregate Concrete

by Jianchao Wang, Jiahe Liang, Yucheng Li and Wei Hou

Buildings 2024, 14(4), 1116; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14041116 - 16 Apr 2024

Viewed by 318

Abstract

To effectively recycle waste petroleum products and construction waste, recycling polypropylene fiber (RPF) and recycled aggregate can be mixed into concrete to make RPF recycled coarse aggregate (RCA) concrete. In this study, the RPF recycled from a polypropylene (PP) packaging belt was used [...] Read more.

To effectively recycle waste petroleum products and construction waste, recycling polypropylene fiber (RPF) and recycled aggregate can be mixed into concrete to make RPF recycled coarse aggregate (RCA) concrete. In this study, the RPF recycled from a polypropylene (PP) packaging belt was used as the test material and manually cut into the shape required for the experiment. The effects of RCA and RPF on the tensile mechanical behavior of concrete are researched. The failure modes and constitutive relationship of the specimens under axial tension and splitting tension are further investigated. The results show that the axial tensile strength of RPF RCA concrete first increased and then decreased with the increase in fiber volume content, and was the largest when the fiber volume content was 1.5%, and its strength increased by 21.14% compared with that of recycled concrete. Its lifting rate relative to recycled concrete is between 13.14–21.41%. The change trend of axial tensile strength with the substitution rate of RCA is that it decreases with the increase in substitution rate, and the substitution rate decreases by 9.64% when the substitution rate is 100% compared with 0%.The peak strain first increased and then decreased with the increase in fiber volume content, and the maximum fiber volume content was 1.5%, which increased by 28.19% compared with that of recycled concrete. The peak strain first increased and then decreased with the increase in fiber length-diameter ratio, and the maximum length-diameter ratio was 47.85, which increased by 18.22% compared with that of recycled concrete. The peak strain increased with the increase in the replacement rate of RCA, and the peak strain at 30%, 60% and 100% was 96.22%, 102.45% and 118.09% when the replacement rate was 0%, respectively. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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18 pages, 6775 KiB

Open AccessArticle

Experimental Study on the Effect of Steel Reinforcement Ration on the Cracking Behaviour of FRP-Strengthened RC Elements

by Andrea Armonico, Laurent Michel, Mohamed Saidi and Emmanuel Ferrier

Buildings 2024, 14(4), 950; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14040950 - 30 Mar 2024

Viewed by 446

Abstract

This paper examines the cracking behaviour of reinforced concrete beams strengthened by externally bonded fiber-reinforced polymer. The crack opening of RC structures is a key parameter for the durability of concrete structures. It is of vital importance for designers to be able to [...] Read more.

This paper examines the cracking behaviour of reinforced concrete beams strengthened by externally bonded fiber-reinforced polymer. The crack opening of RC structures is a key parameter for the durability of concrete structures. It is of vital importance for designers to be able to make correct estimations of the crack opening values of strengthened structures. FRP strengthening affects the cracking behaviour of RC beams with different steel percentages. Beams have been tested under four-point bending mechanical tests until failure with three steel ratios and two layers of externally bonded wet carbon fibers (CFRP). In order to measure the crack opening during loading, Digital Image Correlation is used to obtain the crack opening along the beam during load functioning. The results allow for a comparison of the RC beams with and without FRP and enhance the effect of FRP on crack opening. The crack width was compared with the theoretical values obtained based on the relation proposed by Eurocode 2 (EC2). The comparison enhanced the need to propose a modified relation. Subsequently, an empirical model was established as a modification of EC2, considering the presence of a CFRP system. The corresponding results were compared and discussed to validate the model. For the same level of loads, the crack opening can be reduced by 20 to 50% depending on the level of steel ratio. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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17 pages, 10757 KiB

Open AccessArticle

Effect of Textile Layers and Hydroxypropyl Methylcellulose on Flexural Behavior of TRLC Thin Plates

by Jiyang Wang, Dan Yu, Chen Zeng, Xiaohua Ji, Lingpeng Ye, Pinghuai Zhou and Senlin Zhao

Buildings 2024, 14(4), 924; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14040924 - 28 Mar 2024

Viewed by 451

Abstract

To examine the flexural toughness characteristics of textile-reinforced lightweight aggregate concrete (TRLC), a four-point bending test was conducted to assess the impact of varying numbers of textile layers and the inclusion of hydroxypropyl methylcellulose on the ultimate load-bearing capacity and deformation capacity of [...] Read more.

To examine the flexural toughness characteristics of textile-reinforced lightweight aggregate concrete (TRLC), a four-point bending test was conducted to assess the impact of varying numbers of textile layers and the inclusion of hydroxypropyl methylcellulose on the ultimate load-bearing capacity and deformation capacity of TRLC thin plates. Six groups of specimens were prepared for the experiment, and the bending capacity of the thin plates in each group was evaluated. The flexural toughness index was utilized to quantify the bending performance of TRLC thin plates. The findings revealed that increasing the number of textile layers improved the initial cracking load, initial cracking deflection, ultimate load, ductility, and flexural toughness of the thin plates. For the specimens without HPMC, the initial cracking load was increased by up to 36.1%, the ultimate load by up to 40.9%, and the flexural toughness index by up to 292% as the number of textile layers was increased. For specimens doped with HPMC, the initial cracking load was increased by up to 61.7%, the ultimate load by up to 246.7%, and the flexural toughness index by up to 65%. The TRLC thin plate containing hydroxypropyl methylcellulose exhibited a reduced initial cracking load yet displayed a stronger matrix consistency and good flexural toughness. Moreover, the enhancement in the ultimate load of TRLC thin plates with hydroxypropyl methylcellulose was more pronounced with an increased number of textile layers, resulting in a significantly higher number of cracks compared to TRLC without hydroxypropyl methylcellulose and an 11.40-fold increase in the flexural toughness index. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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17 pages, 4623 KiB

Open AccessArticle

Study on the Stress Threshold of Preventing Interfacial Fatigue Debonding in Concrete Beams Strengthened with Externally-Bonded FRP Laminates

by Xinzhe Min, Dong Yang, Shoutan Song and Xing Li

Buildings 2024, 14(2), 430; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14020430 - 04 Feb 2024

Viewed by 571

Abstract

Externally-bonded FRP laminate is widely used in structural strengthening due to the many advantages of FRP materials. Further enhancement of the strengthening effect can be achieved by inducing prestress into the FRP laminate. However, FRP debonding is still a main issue of this [...] Read more.

Externally-bonded FRP laminate is widely used in structural strengthening due to the many advantages of FRP materials. Further enhancement of the strengthening effect can be achieved by inducing prestress into the FRP laminate. However, FRP debonding is still a main issue of this strengthening method, especially the Intermediate Crack-induced debonding (IC debonding). To better understand the impact of FRP debonding on the strengthening effect, a series of parameter analyses were conducted in this study based on the fatigue life prediction model proposed by the authors. The proposed model involves the fatigue damage accumulation of components of the beam, the mutual interaction between each component, and the impact of FRP fatigue debonding. As a result, a stress threshold for preventing FRP fatigue debonding in strengthening the concrete beam was proposed, which aimed to avoid safety hazards caused by IC debonding in practical engineering. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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18 pages, 8585 KiB

Open AccessArticle

Parametric Study on Mechanical Properties of Basalt Fiber-Reinforced Pea Gravel Concrete

by Jiming Li, Bu Wang, Peng Zhang, Zhenyu Wang and Meng Wang

Buildings 2024, 14(2), 380; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14020380 - 01 Feb 2024

Viewed by 514

Abstract

Basalt fiber-reinforced pea gravel concrete (BFRPGC) has remarkable potential for use as the retrofitting covers for masonry walls. However, a quantitative understanding of the mechanical properties of the BFRPGC material is still a perceived gap in the current literature. In this study, the [...] Read more.

Basalt fiber-reinforced pea gravel concrete (BFRPGC) has remarkable potential for use as the retrofitting covers for masonry walls. However, a quantitative understanding of the mechanical properties of the BFRPGC material is still a perceived gap in the current literature. In this study, the role of basalt fibers in pea gravel concrete was evaluated by a comprehensive experimental investigation involving compressive strength tests and splitting tensile tests. Fiber length and volume fraction were selected as the key parameters. Two fiber lengths of 6 mm and 12 mm were considered, while the volume fraction corresponding to each of the fiber lengths was increased from 0.3% to 0.8%, with a step of 0.1%. The measured strengths were not simply proportional to the fiber volume fraction. The reason behind this phenomenon, i.e., the coupling effect of the bridging role of basalt fibers on concrete microcracks and the fiber agglomeration in concrete, was analyzed. The best performance of the BFRPGC material was achieved by incorporating 12-millimeter-length fibers with a volume fraction of 0.4%. Compared to that of the reference pea gravel concrete, a significant increase of up to 44.5% in compressive strength was recorded in this case. Furthermore, the failure mechanism of basalt fibers in pea gravel concrete was disclosed via the scanning electron microscope observations. In addition, the uniaxial compressive stress–strain model of the BFRPGC material was established. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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32 pages, 43577 KiB

Open AccessArticle

Improved Bond Stress-Slip Relationships for Carbon Fibre-Reinforced Polymer-Strengthened Masonry Triplets

by Seyyed Motasam Hashemi and Ashraf Ayoub

Buildings 2024, 14(1), 257; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings14010257 - 17 Jan 2024

Viewed by 608

Abstract

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical [...] Read more.

Carbon fibre-reinforced polymer (CFRP) emerges as a viable solution for reinforcing unreinforced masonry (URM) walls subjected to shear loads. While masonry structures are straightforward to construct, the complexity of the construction materials, especially in terms of their mechanical properties, poses challenges for numerical studies of their structural behaviour. Walls, being fundamental components in masonry construction, play a crucial role in transferring both horizontal and vertical lateral forces. This study investigates the enhancement of masonry wall behaviour through the reinforcement of CFRP. CFRP reinforcement increases ductility and strength, reducing the risk of failure under shear conditions. Additionally, CFRP composites present a practical solution to strengthening masonry structures compared to traditional reinforcement. However, brick, mortar, and CFRP have not been thoroughly investigated. Experimental tests on the bond behaviour of different configurations of CFRP-retrofitted masonry triplets have not been performed before and are therefore presented in this paper. Triplet specimens, comprising three bricks and two mortar joints, both with and without CFRP strengthening, were subjected to bond testing. The study affirms that masonry triplets strengthened with CFRP under shear loads exhibit strength levels at least four to six times greater than those without CFRP. The experimental work was carried out with eight different CFRP configurations on triplet masonry, and each test was repeated four times. Further, the bond stress-slip relationship in the case of masonry triplets with and without CFRP was predicted with new mathematical equations based on the conducted test results. These equations were included in the commercial finite element software ANSYS and used to conduct simulations of CFRP-reinforced masonry triplets. The numerical results indicate good agreement between the finite element model and the test results. The outcome of this research improves the current knowledge on the use of CFRP to reinforce masonry walls with brick and mortar, which will contribute to the understanding of the effect of CFRP on masonry structures. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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13 pages, 3174 KiB

Open AccessArticle

Nonlinear Coupled Vibration Behavior of BFRP Cables on Long-Span Cable-Stayed Bridges under Parametric Excitation

by Yaqiang Yang, Zixian Zhou, Yanlin Guan, Jianzhe Shi, Qiwei Zhan, Mohamed F. M. Fahmy and Bitao Wu

Buildings 2023, 13(12), 3082; https://0-doi-org.brum.beds.ac.uk/10.3390/buildings13123082 - 11 Dec 2023

Viewed by 751

Abstract

Based on the cable-stayed beam model, this paper studies the nonlinear coupled vibration behavior of basalt fiber-reinforced polymer (BFRP) cables on long-span cable-stayed bridges under parametric excitation. Considering the sag, damping of BFRP cables, and the coupled interactions between stayed cables and the [...] Read more.

Based on the cable-stayed beam model, this paper studies the nonlinear coupled vibration behavior of basalt fiber-reinforced polymer (BFRP) cables on long-span cable-stayed bridges under parametric excitation. Considering the sag, damping of BFRP cables, and the coupled interactions between stayed cables and the main girder, the nonlinear coupling vibration model of the BFRP cable–beam composite structure has been established. Taking the longest cable of Sutong Bridge as a case study, the nonlinear coupled vibration behavior of BFRP cables under parametric excitation has been numerically analyzed using the finite difference method. The analysis results indicate that (1) under parametric excitation, the large amplitude nonlinear vibration of the BFRP cable will be induced with an evident “beat” phenomenon. (2) Under the same parametric excitation, the nonlinear coupling vibration response and the beta frequency of the BFRP cable were both smaller than that of the traditional steel cable. (3) The nonlinear coupling vibration response of the BFRP cable increased with an increment in excitation amplitude and a decrement in cable force. With the increase in the excitation frequency, weight per unit length, and axial stiffness, the nonlinear vibration response of the BFRP cable increased first and then decreased. Meanwhile, the damping ratio of the BFRP cable had no significant influence on the nonlinear coupling vibration. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Concrete in Civil Engineering)

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