Study on bending behaviors of severely pre-cracked RC beams strengthened by BFRP sheets and steel plates

Qin, Zipeng; Tian, Yan; Li, Gang; Liu, Le

doi:10.1016/j.conbuildmat.2019.05.056

Cited by 22 publications

(8 citation statements)

References 31 publications

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“…The measured ultimate load of SRCB1 was about 6.7 times higher than that of RCB1, while the secant stiffness K s was 6.5 times higher than that of RCB1. In contrast, the flexural capacity and secant stiffness were enhanced only by no more than 1.3 times and 3.6 times, respectively, when strengthening RC beams using the methods proposed by other researchers (Hawileh et al, 2014; Helal et al, 2020; Lei et al, 2012; Qin et al, 2019; Su et al, 2010). Therefore, a much better flexural performance can be achieved for strengthening RC beams with the U-shaped steel.…”

Section: Resultsmentioning

confidence: 78%

Experimental study on flexural strengthening of reinforced concrete beams with U-shaped steel under secondary load

Lin

Tang

et al. 2021

Advances in Structural Engineering

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This study proposes a new method to strengthen reinforced concrete (RC) beams with U-shaped steel, which can achieve rapid construction and great improvement in the flexural performance of RC beams. To investigate the influence of secondary load defined as newly applied loads after strengthening on the strengthening effect, a total of nine specimens were tested under four-point bending, including a reference beam, a strengthened beam under initial load, and seven strengthened beams under secondary load. The initial loading degree, the thickness of the bottom plate, and the height of the steel box were the main variables considered in this study. Testing results showed that compared with the reference beam, the flexural performance of strengthened beams was significantly enhanced, indicating the good joint performance of the U-shaped steel and the RC beams. Among the three main variables, the initial loading degree was found to have a minimal effect on the flexural performance while the thickness of the bottom plate and the height of the steel box had considerable influence, with the latter having a more pronounced effect. Testing results also showed that most of the strengthened beams experienced flexural failures, which were reflected by steel web peeling and buckling, and concrete crushing. Moreover, a formula was derived for calculating the flexural capacity of strengthened beams under secondary load. The results from the derived formula were found to be in good agreement with those from experiments.

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Section: Resultsmentioning

confidence: 78%

Experimental study on flexural strengthening of reinforced concrete beams with U-shaped steel under secondary load

Lin

Tang

et al. 2021

Advances in Structural Engineering

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“…Additionally, steel plates inhibited the development of cracks in the concrete at the bottom of RC beams. Qin et al (2019) found that the anchor bolt steel plate reinforcement method had a significant effect on improving the bearing capacity and ductility of RC beams. The flexural capacity and stiffness of the test beam heightened with the increase of steel plate thickness, but which would not increase when the thickness of the steel plate raised to a certain extent, because of the mismatch between the compressive zone at the top of the RC beam and the tensile zone at the bottom of the RC beam caused by the crushing of concrete in the compression zone.…”

Section: Introductionmentioning

confidence: 98%

Flexural behavior of RC beams reinforced by ECC layer and steel plate: numerical simulation

Liu,

Wang,

Xiao

2024

IJSI

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PurposeThe combination of an Engineered Cementitious Composite (ECC) layer and steel plate to reinforce RC beams (ESRB) is a new strengthening method. The ESRB was proposed based on the steel plate at the bottom of RC beams, aiming to solve the problem of over-reinforced RC beams and improve the bearing capacity of RC beams without affecting their ductility.Design/methodology/approachIn this paper, the finite element model of ESRB was established by ABAQUS. The results were compared with the experimental results of ESRB in previous studies and the reliability of the finite element model was verified. On this basis, parameters such as the width of the steel plate, thickness of the ECC layer, damage degree of the original beam and cross-sectional area of longitudinal tensile rebar were analyzed by the verified finite element model. Based on the load–deflection curve of ESRB, ESRB was discussed in terms of ultimate bearing capacity and ductility.FindingsThe results demonstrate that when the width of the steel plate increases, the ultimate load of ESRB increases to 133.22 kN by 11.58% as well as the ductility index increases to 2.39. With the increase of the damage degree of the original beam, the ultimate load of ESRB decreases by 23.7%–91.09 kN and the ductility index decreases to 1.90. With the enhancement of the cross-sectional area of longitudinal tensile rebar, the ultimate bearing capacity of ESRB increases to 126.75 kN by 6.2% and the ductility index elevates to 2.30. Finally, a calculation model for predicting the flexural capacity of ESRB is proposed. The calculated results of the model are in line with the experimental results.Originality/valueBased on the comparative analysis of the test results and numerical simulation results of 11 test beams, this investigation verified the accuracy and reliability of the finite element simulation from the aspects of load–deflection curve, characteristic load and failure mode. Furthermore, based on load–deflection curve, the effects of steel plate width, ECC layer thickness, damage degree of the original beam and cross-sectional area of longitudinal tensile rebar on the ultimate bearing capacity and ductility of ESRB were discussed. Finally, a simplified method was put forward to further verify the effectiveness of ESRB through analytical calculation.

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“…Besides, the stiffness and the natural frequency of the repaired beam increased by approximately 16.6 and 8.0%, respectively, compared to the reference-unrepaired beam. Qin et al 26 showed that the bending capacity of the heavily pre-cracked RC beams strengthened with BFRP sheets could be restored to the same level as that of the reference beam. Asaad et al 27 reported that the flexural capacity of RC beams strengthened with BFRP sheets can be significantly improved and the BFRP sheets can limit the crack propagation of concrete structures and improve their ductility.…”

Section: Introductionmentioning

confidence: 99%

Flexural performance of RC beams externally strengthened with a single-layer of basalt fiber reinforced polymer sheets

Kadhim,

Özakça

2022

Composites and Advanced Materials

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Basalt Fiber Reinforced Polymer (BFRP) is an environment friendly strengthening material that can be used in several engineering applications. In this research, an experimental program was directed to investigate the BFRP strengthening adequacy of reinforced concrete beams. Eight simple-span beams were tested under the four-point bending test and were all made from the same concrete mixture. One layer of BFRP was applied on the soffit of B1, while this layer was wrapped partially along the sides of beams B2, B3, and B4 with vertical side extensions of 25, 75, and 105 mm, respectively, to evaluate the effect of vertical extension of the bottom BFRP layer on the flexural behavior of the strengthened beams. The beams B5 and B6 were strengthened with three BFRP U-strips along the flexural span without and with a bottom layer of BFRP sheet, respectively. On the other hand, the bottom and side surfaces of B7 were fully wrapped with a layer of BFRP, while B0 was kept without strengthening as a reference beam. The test results showed that strengthening with BFRP can noticeably improve the beam load capacity at cracking, yield, and ultimate stages. The ductility of strengthened beams was less than B0 by up to 33% for partial side strengthening and 45% for full side strengthening, while the toughness of all strengthened beams was higher than that of reference beam by 8–78%. The results also showed that increasing the vertical side extension of the bottom BFRP layer leads to significant load capacity increase.

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Study on bending behaviors of severely pre-cracked RC beams strengthened by BFRP sheets and steel plates

Cited by 22 publications

References 31 publications

Experimental study on flexural strengthening of reinforced concrete beams with U-shaped steel under secondary load

Experimental study on flexural strengthening of reinforced concrete beams with U-shaped steel under secondary load

Flexural behavior of RC beams reinforced by ECC layer and steel plate: numerical simulation

Flexural performance of RC beams externally strengthened with a single-layer of basalt fiber reinforced polymer sheets

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