Papers by Keyword: GFRP Bar

Abstract: To alleviate the corrosion issue, GFRP bars are usually preferred over steel reinforcing bars. However, its application causes larger deflection and brittle failure of concrete members. To solve this, steel bars can be used in combination with GFRP bars to reduce deflection and enhance ductility. Steel-GFRP hybrid reinforced concrete is a relatively recent concept, as a result, it is still in the development stage. This study numerically examines the flexure response of concrete beams reinforced with hybrid reinforcement i.e., GFRP bars combined with steel. A total of five numerical models were developed for this investigation. The analysis methodology is based on the models developed for investigation of GFRP reinforced concrete beams which was validated with experimental studies. It is found that with an increase in the replacement percentage of steel in GFRP RC beams, the ultimate load is increased. Also, it is observed that there is a significant reduction in deflection in post-cracking and pre-steel yielding region along with enhancement in the attributes of ductility which is beneficial for serviceability aspects. The steel-GFRP hybrid-reinforced concrete beams were found to have failed by yielding of steel and subsequent concrete crushing.

Abstract: The objectives of this study are to analyze the pattern crack and failure mode of the GFRP concrete beam by using GFRP sheet as shear reinforcement (GFB) compared with the two types of the conventional reinforced concrete beam (CB and GB). One of the conventional reinforced concrete beams is reinforced with the steel bar (CB) and the other is the GFRP bar (GB) as longitudinal reinforcement. The nine beams were cast from one concrete batch with dimensions of 150 mm width, 250 mm depth and 3300 mm length. This study focuses on a simply-supported beam using a roller and pinned supports at the end of the beam. Control beam (CB) that using steel reinforcement shows three phases of deformation based on the deflection load curve, ie before crack, after crack, and after yield, while GB and GFB beams that use GFRP bar reinforcement only show two phases of linear deformation namely the deformation phase before cracking and after cracking. From the crack pattern, CB beams experience the flexural cracks which starting from the mid-span on the tensile side of the constant moment region and propagated to the compression region along with the increase in load. All GB beams show the crack starts from the mid-span and then propagates towards the support. Whereas GFB beam show the flexural cracks that occur in the constant moment region and in the shear span, also diagonal cracks that divide the GFRP sheet occurred. From the failure mode, CB experienced flexural failure, while GB experienced compression failure and shear failure in all GFB beams.

Abstract: Reinforced concrete has been the material mainly used in the repair of traditional structures of historic buildings. However, since the end of the 20th century, it began to question its use, especially for damages arising from corrosion of steel. An alternative is lime concrete reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Current lime concrete provides a high compressive strength and prevent problems such as cement alkalinity. GFRP bars provide the necessary tensile strength. Its modulus of elasticity and adhesion, improved by various mechanisms, allows good compatibility with concrete lime. Mechanical characteristics of the mixture are studied together to withstand the tensions and compressions in historic buildings. This new material is progressively replacing to Portland cement in the restoration of architectural heritage

Abstract: There has been much research conducted on the current performance of Fiber Reinforced Polymer (FRP) as reinforcement. It was due to FRP easier to maintain than steel during construction because of less weight. Laboratory works on the flexural behavior of concrete beams that with GFRP and CFRP use as a plate strengthening for the beam size 2800 x 200 x 250 millimeter. study of the pattern of cracking and failure modes of the beam will be compared between the ten types of beams consisting of steel reinforced beams , beam-reinforced GFRP and GFRP reinforced beams strengthened with CFRP with different lengths. Comparing between the beam bending performance was examined through the ultimate load, cracking and failure modes.

Abstract: In order to obtain GFRP reinforcement bars it is necessary to undertake tests regulated code which require important mechanical tools. This paper presents a method which allows for determining GFRP rebars tensile strength value from their flexural strength value which has been obtained with a simple, inexpensive and reliable test. This method results will be verified by applying it to values obtained in a series of bending tests and comparing these results with values obtained in tensile tests. Values concordance for small diameter GFRP rebars is very good.

Abstract: The GFRP bar has good mechanical properties and durability, but it is hard to test the tensile strength of large diameter FRP bar. Its test method given by ACI is too conservative, especially for large diameter FRP bar, and the length of test specimen will be too long and beyond the range of most testing machine. This article tested the tensile strength of GFRP bar using new methods, meanwhile, analyzed its stress distribution along the length of the specimens. The test results show that the use of bond anchor with steel plug or internal thread to measure the tensile strength of GFRP bar is feasible, and it can reduce the free length and the anchor length of the specimens, thus simplifying the test method of the tensile strength of FRP bars.

Abstract: This study evaluates the flexural performance of reinforced concrete beams with GFRP(Glass Fiber Reinforced Polymer) bars and RCA(Recycled Coarse Aggregates). A total of four specimens with various replacement ratios of RCA (0%, 30%, 50%, and 100%) were tested. An investigation was performed on the influence of RCA with various replacement ratios on load-carrying capacity, post cracking stiffness, cracking pattern, and ductility. The test results showed that replacement ratios of RCA had not a bad effect on concrete compressive strength or flexural strength of beams. They were compared with the design flexural strength and the nominal moment predictions of ACI Code.

Abstract: This paper presents the experimental results of shear behaviour on concrete beams longitudinally reinforced with glass fiber-reinforced polymer (GFRP) reinforcement bars. Totally sixteen concrete beams were tested under static load. Half of the tested beams were longitudinally reinforced with GFRP reinforcement bars, while, the other half were reinforced with conventional steel reinforcement bars. The beams were prepared with varying test variables, such as shear span-to-effective depth ratios (a/d), amount and types of longitudinal reinforcement bars and stirrup spacing. The experimental results show that the ratios of a/d and stirrup spacing significantly influence the ultimate capacities of the beams. Moreover, more closely spaced diagonal shear cracks were resulted in GFRP reinforced concrete (RC) beams compared to steel RC beams.

Abstract: To avoid the creep rupture of GFRP bar in RC members, not exceeding 20% design tensile strength (ffu)) is recommended as design limit for sustained stress level in GFRP bar in current ACI 440.1R-06 guideline. In this paper, the effects of using light weight concrete (LWC) is studied to investigate the sustained stress level in GFRP bar RC bridge decks by a parametric study. Results show that the sustained stress in GFRP bar in LWC bridge decks is in between 2.8-5.7% of ffu, while it is about 3.44-7.52% for normal weight concrete (NWC) deck.

Abstract: In current ACI 440.1R-06 design guideline, an environmental reduction factor (ERF) is specified to account for long-term durability of GFRP bar used in reinforced concrete structures. Such ERF factor is still lack of confidence to concrete industry prior to deliberate calibrations with in-field real time data. In this paper, a parametric study on the design of GFRP bar RC bridge deck per ACI 440 guideline is presented to investigate the stress level in GFRP bar under ultimate design loads per AASHTO LRFD Specifications. Results show that tensile stress in GFRP under ultimate design loads is always less than 25% of GFRP guaranteed tensile strength f*fu, which is much lower than the design strength per as specified in ACI 440 Guideline (i.e., 0.7 f*fu). It showed that GFRP bar RC bridge deck as designed in accordance with ACI 440 guideline could give sufficient safety margin.