Experimental study on flexural behaviour of reinforced concrete beams strengthened with passive and active CFRP strips using a novel anchorage system

Piątek, Bartosz; Siwowski, Tomasz

doi:10.1007/s43452-021-00364-7

Cited by 10 publications

(6 citation statements)

References 28 publications

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“…Among them, a method of near-surface-mounted FRP strips, via cutting a groove into the concrete surface and filling the FRP strips and epoxy paste, can improve the bearing capacity of strengthened reinforced concrete beams compared with those of externally bonded FRP when the reinforcement amount is equivalent [ 20 , 21 , 22 , 23 ]. Meanwhile, the anchoring methods for FRP laminate/sheets with mechanically fastened anchors which prevent the debonding of externally bonded CFRP can effectively delay debonding and enhance the deformability as well as the bearing capacity of strengthened and reinforced concrete elements [ 24 , 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Case Study on Prestressed CFRP Plates Applied for Strengthening Hollow-Section Beam Removed from an Old Bridge

Liu

Bao

et al. 2023

Polymers

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With the wide application of carbon fiber reinforced polymer (CFRP) plate, used for strengthening existed concrete structures, the prestressing technology of CFRP plate is becoming a hot topic, in order to sufficiently develop its high-strength peculiarity. In this paper, a full-scale hollow-section beam with length of 16 m taken from an old bridge which was in service for about 20 years was first examined for existed cracks and repaired by filling epoxy adhesive, and then the beam was strengthened with prestressed CFRP plates. The CFRP plates were tensioned and fixed with flat-plate anchorages at ends and bonded with adhesive on the bottom surface of the beam. The strengthened beam was experimentally studied using a four-point test to measure the concrete strain along the height of the mid-span section and the mid-span deflection. The finite element model of the strengthened beam was verified by the comparison of test results and used for an extending study of parametric analysis considering the effect of the length and amount of CFRP plates. Results indicated that with an increase in the length and amount of CFRP plates, the mid-span deflection of the beam decreases with the increased cracking resistance and bearing capacity, while the ultimate failure mode transfers from the under-reinforcement to the over-reinforcement.

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Section: Introductionmentioning

confidence: 99%

Case Study on Prestressed CFRP Plates Applied for Strengthening Hollow-Section Beam Removed from an Old Bridge

Liu

Bao

et al. 2023

Polymers

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“…According to the study, using the pre-stressed CFRP strips on the margins boosted load capacity by around 11% over using it in the center of the RC beams. Pitek and Siwowski [16] tested five RC beams that were strengthened using passively CF sheets, without and with mechanical anchors, as well as using sheets tensioned by a pre-stressing technique at different pre-stressing rates varying from 30 to 50% of the CFRP tensile capacity. According to the findings, raising the pre-stressing degree of the beams has a significantly favorable impact on the response of strengthened RC beams.…”

Section: Introduction 1behaviour Of Strengthened Rc Beams Using Exter...mentioning

confidence: 99%

Unbonded Pre-Tensioned CF-Laminates Mechanically Anchored to HSC Beams as a Sustainable Repair Solution for Detachment of Bonded CF-Laminates

El Zareef,

Barour,

Kaloop

et al. 2023

Buildings

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The present article outlines a Finite Element Model (FEM) that was created and validated by comparing it to prior experimental investigations to estimate the flexural performance of HSC beams strengthened with exterior bonded, unbonded, and unbonded pre-tensioned Carbon Fibre Reinforced Polymer (CFRP) sheets in several patterns. Nonlinear analysis was performed on three-point-loaded beams using ANSYS software, incorporating the constitutive characteristics of various components (concrete, CFRP, and steel). The comparison of FE-models and experimental data, namely for load-deflection curves, crack patterns, and failure modes, revealed that the developed numerical FE-models and experimental outcomes are in good accord. There has been numerous prior research on the behavior of beams strengthened with externally bonded CFRP sheets, but few on those reinforced with externally unbonded CFRP laminates, and even fewer on HSC beams reinforced with externally unbonded pre-tensioned CFRP laminates. Therefore, the major contribution of this article is to investigate the flexural behavior of HSC beams strengthened utilizing externally unbonded pre-tensioned CFRP laminates. The analysis revealed that the bending performance of RC-beams strengthened using external unbonded pre-tensioned CFRP-laminates is quite similar to that of bonded CFRP-strengthened beams, indicating a high potential for tackling the durability issues caused by detachment of bonded CFRP-strips in such structural elements. The existence of a fully wrapped CF sheet forced the beam to develop diagonal shear cracks in the region between the wrapped CF sheet and beam supports while also enhancing the flexural cracked zone at mid-span to change from smeared to discrete fractures. The flexural fractures spread over a deeper and wider area of the beam as a result of the incorporation of a half-wrap CF laminate. Externally unbonded CFRP-sheets pre-tensioned with 45% of the CFRP ultimate strength utilizing various patterns (straight and U-wrap) performed similarly to bonded CFRP-sheets, with a slight boost in load capacity of around 4.5% and notable reduces in deflection ranging from 9.7% to 16.24%. Using exterior unbonded CFRP laminates to strengthen RC-beams resulted in a flexural capacity increase ranging from 22.3% for NC beams to 71.6% for HSC beams.

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“…Theoretically, prestressing CFRP can not only help us reduce the total amount of CFRP required to effectively utilize its high strength but can also help restore deformations, and the width of existing cracks can be minimized for strengthened structures with restored serviceability [17][18][19][20][21][22][23][24][25]. In regard to prestressed CFRP sheets, effective strength utilization certainly relies on the anchorage approach.…”

Section: Introductionmentioning

confidence: 99%

“…In regard to prestressed CFRP sheets, effective strength utilization certainly relies on the anchorage approach. During the development of prestressing technology, different anchorage systems have been innovated, including the full-length self-anchored with adhesive [19][20][21], flat anchorage [22], steel depression plate [24], CFRP sheet bonded with steel sheet fixed in a steel pocket [25], flat anchorage with circular tooth [26,27] and a wedge-extrusion bond anchorage system [28]. Anchorage efficiency has become high with the development of new types of anchorage systems.…”

Section: Introductionmentioning

confidence: 99%

Flexural Performance of Cracked Reinforced Concrete Beams Strengthened with Prestressed CFRP Sheets under Repeated Loads

Wang,

Li,

Song

et al. 2023

Buildings

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Because researchers are aiming to restore the deformation and minimize the crack width of existing concrete structures, the strengthening technology of prestressed carbon-fiber-reinforced plastic (CFRP) is currently the focus of many studies and applications. In terms of the strengthening of a prestressed CFRP sheet on the flexural performance of cracked reinforced concrete beams under repeated loads, a four-point bending test of 12 beams was conducted considering the prestress degree reflected by the amount and the prestress force of the CFRP sheet. The longitudinal strengthened CFRP sheet was bonded on the bottom surface of the test beam and fixed by U-jacket CFRP sheets at the ends after tensioning. The strains of concrete, longitudinal tensile steel bars and CFRP sheets were measured at the pure bending segment of test beams, while the cracks, midspan deflection and failure pattern were recorded. The results show that the normal strain on the mid-span section of the strengthened beams by the prestress CFRP sheets was fitted for the assumption of plane section, the cracks and mid-span deflection decreased with the prestress degree of the CFRP sheets to provide better serviceability for the strengthened beams, the load capacity could be increased by 41.0–88.8% at the yield of longitudinal tensile steel bars and increased by 41.9–74.8% at the ultimate state and the ductility at the failure state was sharply reduced by 54.9–186%. The peeling off of broken CFRP sheets played a role in controlling the failure pattern of the strengthened beams under repeated loads. Finally, methods for predicting the bending performance of reinforced concrete beams strengthened by prestressed CFRP sheets were proposed. This study enriches the knowledge about damaged reinforced concrete beams that were strengthened with prestressed CFRP sheets.

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Experimental study on flexural behaviour of reinforced concrete beams strengthened with passive and active CFRP strips using a novel anchorage system

Cited by 10 publications

References 28 publications

Case Study on Prestressed CFRP Plates Applied for Strengthening Hollow-Section Beam Removed from an Old Bridge

Case Study on Prestressed CFRP Plates Applied for Strengthening Hollow-Section Beam Removed from an Old Bridge

Unbonded Pre-Tensioned CF-Laminates Mechanically Anchored to HSC Beams as a Sustainable Repair Solution for Detachment of Bonded CF-Laminates

Flexural Performance of Cracked Reinforced Concrete Beams Strengthened with Prestressed CFRP Sheets under Repeated Loads

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