Yes / GFRP profiled-concrete composite beams with groove shear connectors are analyzed using finite the element (FE) analysis. The concrete damaged plasticity (CDP) model was adopted for normal strength concrete (NSC) and reactive powder concrete (RPC). The orthotropic behaviour of GFRP profile was taken into consideration, and the bi-linear traction-separation model was used to investigate the bond-slip behavior between GFRP profile and concrete. Furthermore, parametric studies were conducted to investigate the effects of strength and the cross-sectional dimensions of concrete, strength (orthotropy), and the cross-sectional dimensions (the web height and the thickness of FRP plate). Numerical analysis results correlate well with experimental results. Based on numerical analysis, the composite beam with shear connectors spacing at 100 mm has a deflection-limit load of 21.4 % higher than the specimens with 150 mm spacing. It is possible to improve the bonding behavior of interfaces by using groove shear connectors. The ultimate load and deformation, and pseudo-ductility were significantly improved by using RPC with high strength and toughness (ultimate compressive strain). GFRP profiles with greater orthotropy coefficients provide fully utilized concrete's compressive strength, preventing premature crushing and enhancing composite structure stiffness. Flexural performance of the composite beams can be improved efficiently by choosing the appropriate sectional size during design and construction. / The authors would like to thank the financial support provided by the Natural Science Foundation of Jiangsu Province, China (BK20201436), the Science and Technology Project of Jiangsu Construction System (2018ZD047, 2021ZD06), the Science and Technology Project of Gansu Construction System (JK2021-19), the Open Foundation of Jiangsu Province Engineering Research Center of Prefabricated Building and Intelligent Construction (2021), the High-End Foreign Experts Project of Ministry of Science and Technology, China (G2022014054L), the Science and Technology Cooperation Fund Project of Yangzhou City and Yangzhou University (YZU2022194, YZU212105), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020), the Science and Technology Project of Yangzhou Construction System (2022ZD03, 202204) and the Technology Innovation Cultivation Fund of Yangzhou University (2020-65).

Yes / The flexural performance of geopolymer concrete (GPC) T-beams reinforced longitudinally with GFRP bars under a four-point static bending test was investigated. Six full-scale simply supported T-beams were cast and tested; one control specimen was made with ordinary Portland cement concrete (OPCC), while the other five beams were made of geopolymer concrete. The G-GPC2 was designed to attain the same theoretical moment capacity as the G-OPCC6 control beam. The main parameters investigated were the reinforcement ratio of ρ_f/ρ_b= 0.75, 1.05, 1.12, 1.34 and 1.34 for G-GPC1, G-GPC2, G-GPC3, G-GPC4, and G-GPC5, respectively, and compressive strength of geopolymer concrete. Based on the results of the experiments, the ultimate strain of GPC did not show the same behaviour as that of OPCC, which affects the mode of failure. The beam capacity and deflection were, respectively, overestimated and underestimated using the ACI 440 2R-17 predictive equations.

Purpose: This study aimed at conducting a case study to compare the differences in reinforcement quantity, sustainability goals, and emissions in a concrete slab between fiberglass reinforcement and steel reinforcement. Method:  To calculate and study the amount of reinforcement and emission values for the different materials, a case study was made on a concrete slab for an industrial single-story building with presented dimensions from the structural engineering company Bjerking AB. Data collection consists of interviews with distributors and employees of the construction department at Bjerking and a literature study. The calculations for minimum reinforcement are valid for both steel and fiberglass reinforcement according to Eurokod 2 and DIBt. Results: Several different factors were taken into consideration including change of parameter values for the separate calculations of steel rebars and fiber glass rebars. The required amount of concrete and emission values for both reinforcement materials of each case was based on calculated minimum reinforcement and on data from climate database of Boverket. The results vary between the different materials depending on the calculated amount of reinforcement which is determined by choice of tensile strength and elastic modulus. Conclusions: A larger amount is needed when reinforcing a concrete slab with fiberglass reinforcement than steel due to higher strain values. The amount of concrete with fiberglass reinforcement is almost equal to steel reinforcement. In relation to the sustainability goals the positive effect of fiberglass reinforcement lie in the difference in emission during production, which is lower than steel.      Keywords: GFRP, FRP, reinforcement, steel reinforcement, sustainability goals, Eurocode 2, CO2e.

No description available.

The threat of terrorist bombings and accidental industrial explosions motivates the need for more economical and efficient blast-resistant construction techniques that offer enhanced levels of protection at reduced component damage levels. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. This thesis presents the results of an experimental and analytical investigation on the effect of hybrid arrangements of glass fiber reinforced polymer (GFRP) and conventional mild steel reinforcement on the blast performance of reinforced concrete beams. Seven large-scale reinforced concrete beams with different combinations of tensile steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loading generated using the Virginia Tech Shock Tube Research Facility. The effect of hybrid reinforcing on the blast performance of the beams was evaluated based on the global response, failure mode, damage pattern, mid-span displacement, and support reactions of the tested beams. The results demonstrated several benefits in using hybrid arrangements of steel and GFRP reinforcement. Beams with hybrid reinforcing experienced reduced overall residual displacements compared with similar conventionally reinforced concrete members. This was attributed to the elastic nature of GFRP rebar which was found to produce a self-centering behavior that assisted in returning the hybrid members to their original undeformed position. This permitted the hybrid beams to safely experience larger maximum displacements at substantially less damage than all-steel construction. Furthermore, if the GFRP reinforcement did rupture, the presence of steel arrested hazardous component failure and provided additional energy dissipation and redundancy. Accompanying the experimental tests was an inelastic single-degree-of-freedom analysis to predict the displacement time-history response of the beams. Reasonably good predictions of response were obtained when the advanced material models and the effects of accumulated damage due to repeated blast testing were incorporated into the analytical predictions. Finally, a series of protective design recommendations and a new proposed response limit, that describes the level of damage achieved after a blast event, were established to encourage use of hybrid GFRP/steel reinforcement in blast-resistant construction. / Master of Science / The threat of terrorist bombings and accidental industrial explosions motivate the need for new blast resistant construction techniques. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. Large-scale reinforced concrete beams with different combinations of steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loads, gen-erated by the Virginia Tech Shock Tube Research Facility. The results demonstrated that beams with hybrid reinforcing experienced reduced overall residual damage in comparison with similar conventionally reinforced concrete members. Additionally, if the GFRP rebar ruptured, the presence of steel prevented a brittle failure and provided additional energy dissipation and redundancy. The inelastic single degree of freedom model developed for this investigation resulted in an adequate prediction of the load-deflection characteristics record-ed from experimental testing. To encourage the use of hybrid FRP/steel reinforcement in blast-resistant construction, a series of protective design recommendations and a proposed response limit, that describes the level of damage achieved after a given blast event, were established.

Yes / This paper presents the experimental results of five large-scale hybrid glass fiber reinforced polymer (GFRP)-steel reinforced concrete continuous beams compared with two concrete continuous beams reinforced with either steel or GFRP bars as reference beams. In addition, two simply supported concrete beams reinforced with hybrid GFRP/steel were tested. The amount of longitudinal GFRP, steel reinforcements and area of steel bars to GFRP bars were the main investigated parameter in this study. The experimental results showed that increasing the GFRP reinforcement ratio simultaneously at the sagging and hogging zones resulted in an increase in the load capacity, however, less ductile behaviour. On the other hand, increasing the steel reinforcement ratio at critical sections resulted in more ductile behaviour, however, less load capacity increase after yielding of steel. The test results were compared with code equations and available theoretical models for predicting the beam load capacity and load-deflection response. It was concluded that Yoon's model reasonably predicted the deflection of the hybrid beams tested, whereas, the ACI.440.1R-15 equation underestimated the hybrid beam deflections. It was also shown that the load capacity prediction for hybrid reinforced concrete continuous beams based on a collapse mechanism with plastic hinges at mid-span and central support sections was reasonably close to the experimental failure load. / Higher Education of Libya (972/2007).

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.

Yes / In this study, bond properties of glass fibre reinforced polymer (GFRP) bars embedded in high-strength concrete (HSC) were experimentally investigated using a pull-out test. The experimental program consisted of testing 84 pull-out specimens prepared according to ACI 440.3R-12 standard. The testing of the specimens was carried out considering bar diameter (9.5, 12.7 and 15.9 mm), embedment length (2.5, 5, 7.5 and 10 times bar diameter) and surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) as the main parameters. Twelve pull-out specimens reinforced with 16 mm steel bar were also tested for comparison purposes. Most of the specimens failed by a pull-out mode. Visual inspection of the tested specimens reinforced with GFRP (HW-SC) bars showed that the pull-out failure was due to the damage of outer bar surface, whilst the detachment of the sand coating was responsible for the bond failure of GFRP (SC) reinforced specimens. The bond stress – slip behaviour of GFRP (HW-SC) bars is different from that of GFRP (SC) bars and it was also found that GFRP (SC) bars gave a better bond performance than GFRP (HW-SC) bars. It was observed that the reduction rate of bond strength of both GFRP types with increasing the bar diameter and the embedment length was reduced in the case of high-strength concrete. Bond strength predictions obtained from ACI-440.1R, CSAeS806, CSA-S6 and JSCE design codes were compared with the experimental results. Overall, all design guidelines were conservative in predicting bond strength of both GFRP bars in HSC and ACI predictions were closer to the tested results than other codes.

<p dir="ltr">This project looks into the strength capacity and behavior of GFRP rebars compared to steel rebars. Tested with different adhesives and embedded at multiple embedment depths, this research aims to look how those factors influence the overall performance of the rebars.</p>

Ce travail porte sur l'étude des comportements en flexion à court et long termes des poutres hybrides collées constituées d'un profilé pultrudé GFRP et d'une dalle en béton, assemblés par un joint de colle époxy. L'utilisation du collage dans des structures réelles se heurte encore à la réticence des concepteurs en raison du manque de garanties sur la durabilité à long terme et de l'absence d'outils de modélisation donnant la durée de vie en service des assemblages collés. La présente étude constitue donc un jalon dans cette démarche de compréhension du comportement à long terme de ces structures collées. Elle s'appuie sur analyse multi-échelles qui permet d'aborder le problème à l'échelle locale de l'interface (essai pushout) et à l'échelle globale de l'élément de structure (essai de flexion sur des poutres). Des essais de vieillissement accéléré ont tout d'abord été conduits pour étudier les effets de l'humidité et de la température sur l'adhésif seul et sur l'assemblage structural et il en ressort que l'eau, et notamment une immersion prolongée, s'avère particulièrement néfaste à la résistance au cisaillement des éprouvettes et modifie leur mode de ruine. La réponse instantanée de l'assemblage pultrudé-béton a ensuite été plus amplement étudiée. Grâce à une étude paramétrique expérimentale, une géométrie et une méthode de fabrication des éprouvettes ont été définies pour assurer la reproductibilité des résultats et limiter leur dispersion. De plus, un modèle numérique 3D a été développé dans le code d'éléments finis Cast3m et montre une distribution de contraintes, notamment de cisaillement, non uniforme le long de la surface de collage avec une concentration aux extrémités du joint. Une analyse paramétrique numérique a permis d'identifier les dimensions des dallettes et du joint de colle comme des paramètres influents sur la résistance des éprouvettes. Enfin, le comportement en fluage d'une poutre hybride est étudié. Sous l'effet d'un vieillissement naturel, seul, le joint d'adhésif ne s'avère pas impacté. Des essais de fluage en flexion 3-points ont été effectués pour étudier les réponses à long terme du profilé seul et de la poutre hybride. Ils montrent une augmentation considérable du déplacement des poutres en raison du fluage et du retrait du béton et du fluage du profilé. Des modèles 3D en variables locales, dans le cadre de la viscoélasticité linéaire, sont développés dans Cast3m et permettent de fidèlement restituer l'évolution des déplacements et des états de déformation au cours du temps pour les différentes poutres testée / This dissertation focuses on the short- and long-term responses of bonded hybrid beams consisting of a GFRP-pultruded profile bonded by an epoxy adhesive joint to a reinforced concrete-slab. The problems related to the durability and the long-term response of these structures still represent an open issue. The present study is meant to increase the knowledge and understanding of these hybrid structures in this context. Firstly, different accelerated ageing tests were carried out to evaluate the effects of some environmental agents such as water, moisture and freeze thaw cycles in the behaviour of GFRP/concrete bonded assemblies. Mechanical characterizations were carried out on control and exposed of both materials and push-out specimens to quantify the degradation and damage of the mechanical resistance of each material and of the adhesive bond properties. The water effect on the adhesion of the joints was found to be significant, especially at longer immersion times. The second part was directed at characterizing the push-out test. An experimental parametric study was performed to elaborate a methodology of fabrication of the push-out specimens that can reduce the dispersion of results and give an accurate prediction of the shear strength on a limited set of specimens. Also, a 3D finite-element model was developed using the finite-element code Cast3m. This model showed that the stress components, especially peel and shear stresses, are not constants across the bonding area and peaking near the free edges (stress concentrations). A numerical parametric study allowed to conclude that the most effective geometrical parameters influencing bond between GFRP and concrete were the bonded length and the dimensions of the concrete substrate. Last part deals with experimental and numerical investigations carried out to study the short- and long-term flexural behaviour of full-scale hybrid beams. All experiments showed considerable increase in beam deflection over time due to concrete creep and shrinkage and GFRP creep. Finally, 3D-finite-element models, realized with Cast3m, are developed based on the incremental formulation of the linear-viscoelasticity theory. The proposed models allow evaluation of the long-term deflection of the pultruded and hybrid beams. Using the proposed model, evolution with time of stresses, strains and displacements in different location of the hybrid beam are obtained