Yes / The current paper aimed at investigating the flexural performance of five large-scale continuous concrete beams reinforced by both steel bars and glass fibre reinforced polymer (GFRP). All the studied specimens had the same geometrical dimensions, with 200mm width, 300mm depth, and two identical spans of 2600mm. The quantity of longitudinal steel reinforcement, GFRP reinforcement, and hybrid reinforcement ratio at the top and bottom layers of beams were the key parameters explored in this study. The experimental findings indicated that using the hybrid reinforcement of steel and GFRP in multi-span continuous concrete beams exhibited a ductile behaviour. However, the hybrid ratio of steel bars/GFRP is critical for restricting the extent of moment redistribution ratios. Moreover, using the same hybrid reinforcement ratios at sagging and hogging regions led to a limited moment redistribution. On the other hand, the hybrid beams strengthened by various hybrid ratios in the critical sections of the tested beams demonstrated a remarkable moment redistribution up to 43%. The test results were compared with the available theoretical model and equations for predicting the beams’ moment capacity. It was found that the ACI.440.2R-08 reasonably predicted the flexural capacity of tested beams whereas the Yinghao and Yong equation underestimated the flexural capacity in the hogging sections. It was also shown that using the collapse mechanism with plastic hinges at sagging and hogging sections yielded good predictions for the loading capacity of hybrid reinforced concrete continuous beams.

This thesis has investigated the application of CFRP and GFRP bars as longitudinal reinforcement for continuously supported concrete beams. Two series of simply and continuously supported CFRP and GFRP reinforced concrete beams were tested in flexure. In addition, a continuously supported steel reinforced concrete beam was tested for comparison purposes. The FRP reinforced concrete continuous beams were reinforced in a way to accomplish three possible reinforcement combinations at the top and bottom layers of such continuous beams. The experimental results revealed that over-reinforcing the bottom layer of either the simply or continuously supported FRP beams is a key factor in controlling the width and propagation of cracks, enhancing the load capacity, and reducing the deflection of such beams. However, continuous concrete beams reinforced with CFRP bars exhibited a remarkable wide crack over the middle support that significantly influenced their behaviour. The ACI 440.1R-06 equations have been validated against experimental results of beams tested. 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. However, The potential capabilities of these equations for predicting the load capacity and deflection of continuous CFRP reinforced concrete beams have, however, been adversely affected by the de-bonding of top CFRP bars from concrete. An analytical technique, which presents an iterative procedure based on satisfying force equilibrium and deformation compatibility conditions, has been introduced in this research. This technique developed a computer program to investigate flexural behaviour in particular the flexural strength and deflection of simple and continuously supported FRP reinforced concrete beams. The analytical modelling program has been compared against different prediction methods, namely ACI 440, the bilinear method, mean moment inertia method and Benmokrane¿s method. This comparison revealed the reliability of this programme in producing more enhanced results in predicting the behaviour of the FRP reinforced beams more than the above stated methods.

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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The incidence of type 2 diabetes is considered an epidemic in Western countries, and its prevalence is more common in the Hispanic population than in non-Hispanic whites. Postprandial hyperglycemia has been associated with oxidative stress (OS), thus; reducing postprandial glycemia and/or OS through dietary consumption of resistant starch (RS) may be one approach to help modulate glucose and insulin responses. The purpose of this study was twofold: 1) to evaluate the physicochemical and sensory properties of cereal food products supplemented with RS. 2) to compare the effects of a single ingestion of granola bars with high (~18 grams of RS) and low (~0 grams of RS) RS compositions on the postprandial glucose and insulin responses (n=14) and oxidative stress parameters (cellular glutathione peroxidase, F2- isoprostanes, and oxygen radical absorbance capacity) in Hispanic women (n=9). Granola bars and cereals were developed to provide 2 levels (10% and 15%) of RS; isocaloric (0% RS) control samples were prepared with readily digestible (high amylopectin) starch. Samples were stored for up to 4 weeks at 20 °C. Mean composition of the high RS granola bars was 6% protein, 15% moisture, and 18% lipid. RS levels slightly increased from 14 to 16 g/serving after 4 weeks of storage, supporting published research that RS increases with storage due to retrogradation and crystallization of amylose chains. Color became lighter as the level of RS increased (p<0.001). Granola bars containing RS were less brittle (p=0.0043) than control granola bars. Sensory results indicated granola bars/cereals were acceptable. RS-supplemented granola bars were then used for the evaluation of RS ingestion in humans. There was no difference in postprandial glucose and insulin responses after a single ingestion of a RS-supplemented (18 g) granola bar. No differences were found in the oxidative stress parameters measured. In a subgroup of subjects (n=9), a lower glucose response 30 minutes after RS consumption was found (p=0.0496). Thus, RS consumption may lower fluctuations in blood glucose, which may help manage glucose levels in individuals at risk of type 2 diabetes. Further studies of short term RS consumption are warranted to elucidate its benefits in glucose management. / Ph. D.

The primary objective of this research was to investigate the shear strength of concrete bridge decks with GFRP top-mat reinforcement. Several models currently exist to predict the shear strength during the design process; however, previous research at Virginia Tech indicates that the existing equations are overly conservative. For this research, a series of concrete decks with varying lengths were tested in a laboratory environment in a two-span continuous configuration, during which data was collected on deflections, rebar strain, crack widths, and ultimate load. It was concluded that the existing equations, particularly the guidelines of ACI 440, are grossly over-conservative for GFRP-reinforced concrete bridge decks continuous over multiple supports. It was suggested that this is due to multiple factors, including additional support provided by the typically-neglected steel reinforcement in the bottom mat and a higher shear strength of the uncracked portion of concrete due to higher compressive stresses in the section as a result of the continuous deck configuration. The second objective of this research was to investigate the effects of environmental exposure on the composite deck and the individual GFRP rebar. Three deck specimens were subjected to differing environmental conditions, including one that was placed into service at an interstate weigh station. All three decks were tested in the same manner as those in the shear investigation. Additionally, live load tests were conducted on the weigh station deck during the time it was in place and tensile tests were conducted on rebar that were extracted from the concrete decks. In the live load testing, the GFRP strains increased by more than 200% over the period of service, which was likely due to a combination of a reduction in GFRP stiffness and a greater amount of cracking. During the laboratory tests on the decks, no clear correlation between conditioning and deflections or cracking was found. The ultimate strength actually increased with conditioning, with the weigh station specimen exhibiting the highest shear strength. Finally, the results of the rebar tensile tests suggested a decrease in both modulus of elasticity and ultimate tensile strength of the GFRP with environmental exposure when compared to unconditioned bars. / Master of Science

The purpose of this research was to investigate the effectiveness and durability of GFRP bars as reinforcement for concrete decks. Today's rapid bridge deck deterioration is calling for a replacement for steel reinforcement. The advantages of GFRP such as its high tensile strength, light weight, and resistance to corrosion make it an attractive alternative to steel. The first objective of this research was to perform live load testing on a bridge deck reinforced with GFRP in one span and steel in the other. The results were compared to the findings from the initial testing performed one year earlier. The strains and deflections of the bridge deck were recorded and the two spans compared. Transverse stresses in the GFRP bars, girder distribution factors, and dynamic load allowances were calculated for both spans. From the live load tests, it was concluded that the GFRP-reinforced span results were within design parameters. The only concern was the increased impact factor values. The second objective was to perform live load tests on a slab reinforced with GFRP installed at a weigh station. Two live load tests were performed approximately five months apart. Peak strains in the GFRP and steel bars were recorded and compared. The peak stresses had increased over time but were within design allowable stress limits. The third objective of this research was to investigate the long term behavior and durability of the GFRP reinforcing bars cast in a concrete deck. The strain gauges, vibrating wire gauges, and thermocouples in the bridge deck were monitored for approximately one year using a permanent data acquisition system. Daily, monthly, and long term fluctuations in temperature and stresses were examined. It was concluded that the vibrating wire gauges were more reliable than the electrical resistance strain gauges. It was further observed that the main influence over strain changes was temperature fluctuations. / Master of Science

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.