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Flexural behaviour of hybrid steel-GFRP reinforced concrete continuous T-beamsAlmahmood, Hanady A.A., Ashour, Ashraf, Sheehan, Therese 10 August 2020 (has links)
Yes / This paper presents test results of six full scale reinforced concrete continuous T beams. One beam was reinforced with glass fibre reinforced polymer (GFRP) bars while the other five beams were reinforced with a different combination of GFRP and steel bars. The ratio of GFRP to steel reinforcement at both mid-span and middle-support sections was the main parameter investigated. The results showed that adding steel reinforcement to GFRP reinforced concrete T-beams improves the flexural stiffness, ductility and serviceability in terms of crack width and deflection control. However, the moment redistribution at failure was limited because of the early yielding of steel reinforcement at a beam section that does not reach its moment capacity and could still carry more loads due to the presence of FRP reinforcement.
The experimental results were compared with the ultimate moment prediction of ACI 440.2R-17, and with the existing theoretical equations for deflection prediction. It was found that the ACI 440.2R-17 reasonably estimated the moment capacity of both mid-span and middle support sections. Conversely, the available theoretical deflection models underestimated the deflection of hybrid reinforced concrete T-beams at all load stages.
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Flexural Behavior of Continuous GFRP Reinforced Concrete Beams.Habeeb, M.N., Ashour, Ashraf 04 1900 (has links)
Yes / The results of testing two simply and three continuously supported concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars are presented. The amount of GFRP reinforcement was the main parameter investigated. Over and under GFRP reinforcements were applied for the simply supported concrete beams. Three different GFRP reinforcement combinations of over and under reinforcement ratios were used for the top and bottom layers of the continuous concrete beams tested. A concrete continuous beam reinforced with steel bars was also tested for comparison purposes. The experimental results revealed that over-reinforcing the bottom layer of either the simply or continuously supported GFRP beams is a key factor in controlling the width and propagation of cracks, enhancing the load capacity, and reducing the deflection of such beams. Comparisons between experimental results and those obtained from simplified methods proposed by the ACI 440 Committee show that ACI 440.1R-06 equations can reasonably predict the load capacity and deflection of the simply and continuously supported GFRP reinforced concrete beams tested.
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Behaviour of continuous concrete T-beams reinforced with hybrid FRP/Steel barsAlmahmood, Hanady A.A. January 2020 (has links)
This work aims to investigate the flexural behaviour of continuous hybrid
reinforced concrete T-beams (HRCT). The investigations consist of three parts;
the computational part, the experimental part and the finite element analysis. The
computational part included two parts, the first one is developing an analytical
programme using MATLAB software to investigate the moment-curvature
behaviour of HRCT-beams and to design the experimental specimens. This was
followed by the experimental part, where six full-scale reinforced concrete
continuous T beams were prepared and tested. One beam was reinforced with
glass fibre reinforced polymer (GFRP) bars while the other five beams were
reinforced with a different combination of GFRP and steel bars. The ratio of GFRP
to steel reinforcement at both mid-span and middle-support sections was the
main parameter investigated. The results showed that adding steel reinforcement
to GFRP reinforced concrete T-beams improves the axial stiffness, ductility and
serviceability in terms of crack width and deflection control. However, the moment
redistribution at failure was limited because of the early yielding of steel
reinforcement at the beam section that did not reach its moment capacity and
could still carry more loads due to the presence of FRP reinforcement.
The second part of the computational part included the comparison between the
experimental results with the ultimate moment prediction of ACI 440.2R-17, and
with the existing theoretical equations for moment capacity, load capacity, and
deflection prediction. It was found that the ACI 440.2R-17 design code equations
reasonably estimated the moment capacity of both mid-span and middle-support
sections and consequently predicted the load capacity of the HRCT-beams
based on fully ductile behaviour. However, Qu's and Safan's equations
underestimated the predicted moment and load-capacity of HRCT-beams. Also,
Bischoff's and Yoon's models underestimated the deflection at all stages of the
load for both GFRP and HRCT- beams.
For the numerical part, a three-dimensional finite element model has been
developed using ABAQUS software to examine the behaviour of HRCT-beams.
The experimental results were used to validate the accuracy of the FEM, where
an acceptable agreement between the simulated and experimental results was
observed. Accordingly, the model was used to predict the structural behaviour of
continuous HRCT-beams by testing different parameters.
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Sagging and hogging strengthening of continuous reinforced concrete beams using CFRP sheets.El-Refaie, S.A., Ashour, Ashraf, Garrity, S.W. 07 1900 (has links)
Yes / This paper reports the testing of 11 reinforced concrete (RC) two-span beams strengthened in flexure with externally bonded carbon fiber-reinforced polymer (CFRP) sheets. The beams were classified into two groups according to the arrangement of the internal steel reinforcement. Each group included one unstrengthened control beam. The main parameters studied were the position, length, and number of CFRP layers. External strengthening using CFRP sheets was found to increase the beam load capacity. All strengthened beams exhibited less ductility compared with the unstrengthened control beams, however, and showed undesirable sudden failure modes. There was an optimum number of CFRP layers beyond which there was no further enhancement in the beam capacity. Extending the CFRP sheet length to cover the entire hogging or sagging zones did not prevent peeling failure of the CFRP sheets, which was the dominant failure mode of beams tested.
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Shear Behaviour of Deep Reinforced Concrete Members Subjected to Uniform LoadPerkins, Stephen M. J. 25 August 2011 (has links)
Experiments were conducted to investigate the shear behaviour of large deep beams subjected to uniform load. Six tests were performed on specimens with identical cross sections and reinforcing, but under different loading configurations. Variables included: span, degree of cracking prior to loading, proximity to a disturbed region near a reaction, and type of flexural stress on the loaded face.
The findings indicate a specific set of variables resulting in unconservative predictions made using a strut-and-tie model for simply-supported beams subjected to uniform load, confirming and validating recent results by other researchers. A fanning strut model is proposed and is shown to provide more conservative results. The emerging trend of high capacity in continuous uniformly-loaded specimens is supported by the experimental results, as is the high capacity of specimens uniformly-loaded on their flexural tension face. Further, the high strength of specimens with suboptimal crack orientations supports recent experimental work.
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Shear Behaviour of Deep Reinforced Concrete Members Subjected to Uniform LoadPerkins, Stephen M. J. 25 August 2011 (has links)
Experiments were conducted to investigate the shear behaviour of large deep beams subjected to uniform load. Six tests were performed on specimens with identical cross sections and reinforcing, but under different loading configurations. Variables included: span, degree of cracking prior to loading, proximity to a disturbed region near a reaction, and type of flexural stress on the loaded face.
The findings indicate a specific set of variables resulting in unconservative predictions made using a strut-and-tie model for simply-supported beams subjected to uniform load, confirming and validating recent results by other researchers. A fanning strut model is proposed and is shown to provide more conservative results. The emerging trend of high capacity in continuous uniformly-loaded specimens is supported by the experimental results, as is the high capacity of specimens uniformly-loaded on their flexural tension face. Further, the high strength of specimens with suboptimal crack orientations supports recent experimental work.
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Continuous Beam of Laser-Cooled Ytterbium Atoms for Precision MeasurementsRathod, Ketan D January 2014 (has links) (PDF)
What if an elementary particle such as an electron had an intrinsic electric dipole moment (EDM)? Existence of such an EDM would be an indication of time-reversal symmetry
violation in the laws of Physics. The Standard model of Physics is considered incomplete, and theories that go beyond the standard model predict existence of such EDM’s within experimental reach. Experiments that search for their existence serve as a test bed for these theories. Use of laser-cooled Yb atoms launched in a fountain for EDM search has been proposed earlier.
This thesis describes the main experimental work on generating a continuous cold
beam of Yb atoms using laser cooling. Such cold beams are ideal for performing EDM
experiments and have several advantages over the more common pulsed fountain. We
demonstrate two ways to achieve this (i) extracting the beam from atoms trapped in 2-
dimensions and (ii) deflecting the atomic beam using 1D-optical molasses. We find that
the latter method gives a longitudinal temperature of 41 mK, which is a factor of 3 better than the former one. We also demonstrate the implementation of Ramsey’s separated oscillatory field technique in a thermal beam to measure the larmor precession frequency with high precision. This serves as a first step towards implementation with cold beam.
Extending the work reported here, we suggest future experiment for measuring an EDM.
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