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Test of concrete flanged beams reinforced with CFRP barsAshour, Ashraf F., Family, M. January 2006 (has links)
Tests results of three flanged and two rectangular cross-section concrete beams reinforced with carbon fibre
reinforced polymer (CFRP) bars are reported. In addition, a companion concrete flanged beam reinforced with
steel bars is tested for comparison purposes. The amount of CFRP reinforcement used and flange thickness were
the main parameters investigated in the test specimens. One CFRP reinforced concrete rectangular beam exhibited
concrete crushing failure mode, whereas the other four CFRP reinforced concrete beams failed owing to tensile
rupture of CFRP bars. The ACI 440 design guide for FRP reinforced concrete members underestimated the moment
capacity of beams failed owing to CFRP tensile rupture and reasonably predicted deflections of the beams tested. A
simplified theoretical analysis for estimating the moment capacity of concrete flanged beams reinforced with FRP
bars was developed. The experimental moment capacity of the CFRP reinforced concrete beams tested compared
favourably with that predicted by the theoretical analysis developed.
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Tests of Continuous Concrete Slabs Reinforced with Carbon Fibre Reinforced Polymer BarsMahroug, Mohamed E.M., Ashour, Ashraf, Lam, Dennis January 2013 (has links)
No / Paper accepted for conference.
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Improving bond of fiber-reinforced polymer bars with concrete through incorporating nanomaterialsWang, X., Ding, S., Qiu, L., Ashour, Ashraf, Wang, Y., Han, B., Ou, J. 07 May 2022 (has links)
Yes / The bond between FRP bars and concrete, the foremost performance for implementation of such reinforcements to corrosion-free concrete structures, is still unsatisfied due to the weak nature of duplex film in the interface. The existing approaches show low efficiency in improving the microstructures and bond between FRP bars and concrete. To address these issues, this paper provided a new approach for improving the bond between FRP bars and concrete by incorporating nanomaterials, as well as explored the modifying mechanisms and established the bond-slip models. For these purposes, the pull-out test, scanning electron microscope observation, as well as energy dispersive spectrometry analysis were performed. The experimental results demonstrated that the presence of nanomaterials increased the ultimate bond strengths between glass/carbon FRP bars and concrete by up to 16.2% and 37.8%, while the corresponding slips decreased by 28.7% and 35.4%, respectively. Such modification effects can be attributed to the optimized intrinsic composition and the reduced pore content of hydration products in the interface, especially in the duplex film, through the nanomaterial enrichment and nano-core effects. The bond-slip relationship between FRP bars and concrete with nanomaterials can be accurately predicted by the mBPE model. / The authors would like to thank the funding offered by the National Science Foundation of China (51978127 and 51908103), and the Fundamental Research Funds for the Central Universities (DUT21RC(3) 039).
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Punching shear of concrete flat slabs reinforced with fibre reinforced polymer barsAl Ajami, Abdulhamid January 2018 (has links)
Fibre reinforcement polymers (FRP) are non-corrodible materials used instead of
conventional steel and have been approved to be an effective way to overcome
corrosion problems. FRP, in most cases, can have a higher tensile strength, but
a lower tensile modulus of elasticity compared to that of conventional steel bars.
This study aimed to examine flat slab specimens reinforced with glass fibre
reinforced polymer (GFRP) and steel bar materials for punching shear behaviour.
Six full-scale two-way slab specimens were constructed and tested under
concentric load up to failure. One of the main objectives is to study the effect of
reinforcement spacing with the same reinforcement ratio on the punching shear
strength. In addition, two other parameters were considered, namely, slab depth,
and compressive strength of concrete.
The punching shear provisions of two code of practises CSA S806 (Canadian
Standards 2012) and JSCE (JSCE et al. 1997) reasonably predicted the load
capacity of GFRP reinforced concrete flat slab, whereas, ACI 440 (ACI
Committee 440 2015) showed very conservative load capacity prediction.
On the other hand, a dynamic explicit solver in nonlinear finite element (FE)
modelling is used to analyse a connection of column to concrete flat slabs
reinforced with GFRP bars in terms of ultimate punching load. All FE modelling was performed in 3D with the appropriate adoption of element size and mesh.
The numerical and experimental results were compared in order to evaluate the
developed FE, aiming to predict the behaviour of punching shear in the concrete
flat slab. In addition, a parametric study was created to explore the behaviour of
GFRP reinforced concrete flat slab with three parameters, namely, concrete
strength, shear load perimeter to effective depth ratio, and, flexural reinforcement
ratio. It was concluded that the developed models could accurately capture the
behaviour of GFRP reinforced concrete flat slabs subjected to a concentrated
load.
Artificial Neural Networks (ANN) is used in this research to predict punching
shear strength, and the results were shown to match more closely with the
experimental results. A parametric study was performed to investigate the effects
of five parameters on punching shear capacity of GFRP reinforced concrete flat
slab. The parametric investigation revealed that the effective depth has the most
substantial impact on the load carrying capacity of the punching shear followed
by reinforcement ratio, column perimeter, the compressive strength of the
concrete, and, the elastic modulus of the reinforcement.
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Flexural behavior of hybrid FRP/steel reinforced concrete beamsKara, Ilker F., Ashour, Ashraf, Köroğlu, Mehmet A. 01 April 2015 (has links)
No / This paper presents a numerical method for estimating the curvature, deflection and moment capacity of hybrid FRP/steel reinforced concrete beams. A sectional analysis is first carried out to predict the moment-curvature relationship from which beam deflection and moment capacity are then calculated. Based on the amount of FRP bars, different failure modes were identified, namely tensile rupture of FRP bars and concrete crushing before or after yielding of steel reinforcement. Comparisons between theoretical and experimental results of tests conducted elsewhere show that the proposed numerical technique can accurately predict moment capacity, curvature and deflection of hybrid FRP/steel reinforced concrete beams. The numerical results also indicated that beam ductility and stiffness are improved when steel reinforcement is added to FRP reinforced concrete beams. (C) 2015 Elsevier Ltd. All rights reserved,
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Load capacity predictions of continuous concrete deep beams reinforced with GFRP barsShalookh, Othman H. Zinkaah, Ashour, Ashraf 26 February 2019 (has links)
Yes / Nine continuous concrete deep beams reinforced with glass fibre reinforced polymer (GFRP) bars were experimentally tested to failure. Three main parameters were investigated, namely, shear span-to-overall depth ratio, web reinforcement and size effect. The experimental results confirmed the impacts of web reinforcement and size effect that were not considered by the strut-and-tie method (STM) of the only code provision, the Canadian S806-12, that addressed such elements. The experimental results were employed to evaluate the applicability of the methods suggested by the American, European and Canadian codes as well as the previous studies to predict the load capacities of continuous deep beams reinforced with GFRP bars. It was found that these methods were unable to reflect the influences of size effect and/or web reinforcement, the impact of which has been confirmed by the current experimental investigation. Therefore, a new effectiveness factor was recommended to be used with the STM. Additionally, an upper-bound analysis was developed to predict the load capacity of the tested specimens considering a reduced bond strength of GFRP bars. A good agreement between the predicted results and the experimental ones was obtained with the mean and coefficient of variation values of 1.02 and 5.9%, respectively, for the STM and 1.03 and 8.6%, respectively, for the upper-bound analysis. / Higher Committee of Education Development in Iraq (HCED)
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Behaviour of continuous concrete deep beams reinforced with GFRP barsShalookh, Othman H. Zinkaah January 2019 (has links)
This research aims to investigate the behaviour of glass fibre reinforced
polymer bars (GFRP) reinforced continuous concrete deep beams. For this
purpose, experimental, analytical and numerical studies were conducted.
Nine continuous concrete deep beams reinforced with GFRP bars and one
specimen reinforced with steel bars were experimentally tested to failure. The
investigated parameters included shear span-to-overall depth ratio (𝑎/ℎ), size
effect and web reinforcement ratio. Two 𝑎/ℎ ratios of 1.0 and 1.7 and three
section heights of 300 mm, 600 mm and 800 mm as well as two web
reinforcement ratios of 0% and 0.4% were used. The longitudinal
reinforcement, compressive strength and beam width were kept constant at
1.2%, ≈55 MPa and 175 mm, respectively. The web reinforcement ratio
achieved the minimum requirements of the CSA S806-12. The experimental
results highlighted that the web reinforcement ratio improved the load
capacities by about 10% and 18% for specimens having 𝑎/ℎ ratios of 1.0 and
1.7, respectively. For specimens with web reinforcement, the increase of 𝑎/ℎ
ratio from 1.0 to 1.7 led to reductions in the load carrying capacity by about
33% and 29% for beams with overall depths of 300 mm and 600 mm,
respectively. Additionally, a considerable reduction occurred in the shear
strength due to the increase of the section depth from 300 mm to 600 mm. The
experimental results confirmed the impacts of web reinforcement and size
effect that were not considered by the strut-and-tie method (STM) of the only
code provision, the Canadian S806-12, that addressed such elements.
In this study, the STM was illustrated and simplified to be adopted for GFRP
RC continuous deep beams, and then, the experimental results obtained from
this study were employed to assess the performance of the effectiveness
factors suggested by the STMs of the American (ACI 318-2014), European
(EC2-04) and Canadian (S806-12) codes as well as those factors
recommended by the previous studies to predict the load capacities. It was
found that these methods were unable to reflect the influences of member size
and/or web reinforcement reasonably, the impact of which has been confirmed
by the current experimental investigation. Therefore, a new effectiveness
factor was recommended to be used with the STM. Additionally, an upper bound analysis was developed to predict the load capacities of the tested specimens considering a reduced bond strength of GFRP bars after assessing
the old version recommended for steel RC continuous deep beams. A good
agreement between the predicted results and the measured ones was
obtained with the mean and coefficient of variation values for
experimental/calculated results of 1.02 and 5.9%, respectively, for the STM
and 1.03 and 8.6%, respectively, for the upper-bound analysis.
A 2D finite element analysis using ABAQUS/Explicit approach was carried out
to introduce a model able to estimate the response of GFRP RC continuous
deep beams. Based on the experimental results extracted from the pullout
tests, the interface between the longitudinal reinforcement and concrete
surface was modelled using a cohesive element (COH2D4) tool available in
ABAQUS. Furthermore, a perfect bond between the longitudinal reinforcement
and surrounding concrete was also modelled to evaluate the validity of this
assumption introduced by many previous FE studies. To achieve a reasonable
agreement with the test results, a sensitivity analysis was implemented to
select the proper mesh size and concrete model variables. The suitability and
capability of the developed FE model were demonstrated by comparing its
predictions with the test results of beams tested experimentally. Model
validation showed a reasonable agreement with the experiments in terms of
the failure mode, total failure load and the load-deflection responses. The
perfect bond model has overestimated the predicted results in terms of
stiffness behaviour and failure load, while the cohesive element model was
more suitable to reflect the behaviour of those specimens. The validated FE
model was then employed to implement a parametric study for the key
parameters that govern the behaviour of beams tested and to achieve an in depth understanding of such elements. The parametric study showed that the
higher the 𝑎/ℎ ratio the more pronounced the effect of web and the longitudinal
reinforcements and the lower the effect of concrete compressive strength; and
vice versa when 𝑎/ℎ ratio reduces.
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