Surface Interaction Studies on Glass Fiber Reinforced Polymer Bars

2007 ◽  
Vol 345-346 ◽  
pp. 1217-1220
Author(s):  
Jung Yoon Lee
Keyword(s):  
High Strength ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Interfacial Bond ◽  
Glass Fiber Reinforced Polymer ◽  
Bond Failure ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Frp Bars

The use of fiber reinforced polymer (FRP) bars has been gaining increasing popularity in the civil engineering community due to their favorable properties such as high-strength-to-weight ratio and good corrosion resistance. In order for concrete to be FRP reinforced, there must be interfacial bond between FRP bars and concrete. The interfacial bond behavior of FRP bars to concrete is expected to vary from that of conventional steel bars, since various key parameters that influence bond performance are different. This paper presents the results of an experimental and analytical study on the interfacial surface interaction of glass fiber reinforced polymer (GFRP) bars in high strength concrete cube. The experimental program consisted of testing 54 concrete cubes prepared according to CSA S802-02 standard 1). The split specimens showed that interfacial bond failure of the steel bar occurred due to concrete crushing in front of the bar deformations, while interfacial bond failure of the GFRP bars occurred partly on the surface of the bar and partly in the concrete by peeling of the surface layer of the bar.

Tension stiffening and cracking of concrete reinforced with glass fiber reinforced polymer (GFRP) bars

2004 ◽  
Vol 31 (4) ◽  
pp. 579-588 ◽  
Author(s):  
Peter H Bischoff ◽  
Richard Paixao
Keyword(s):  
Reinforced Concrete ◽  
Glass Fiber ◽  
Crack Spacing ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Tension Stiffening ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

Tension stiffening and cracking of axial tension members is evaluated for concrete reinforced with steel (reinforcing ratio ρ = 2.0%) and glass fiber reinforced polymer (GFRP) bars (1.3%, 2.0%, and 2.9%), with shrinkage included in the analysis of the member response. Results show that because of a lower bar stiffness the GFRP-reinforced concrete exhibits greater tension stiffening than steel-reinforced concrete for any given value of axial member strain. Transverse cracking in the GFRP-reinforced concrete does not stabilize until much higher values of axial strain are reached, and longitudinal splitting cracks are also evident before cracking has stabilized. Crack widths in concrete reinforced with GFRP bars are larger because of their lower bar stiffness in combination with an increased crack spacing during the crack development stage. Tension stiffening of cracked reinforced concrete is taken into account using an average stress-strain response with a descending branch to model the concrete in tension. A tension stiffening factor is used to characterize this tensile property with an empirical relationship related to the reinforcing bar stiffness and independent of both concrete strength and reinforcing ratio. Results are also compared with the predicted member response based on the 1978 Comité Euro-International du Béton (CEB) CEB-FIP model code approach and American Concrete Institute (ACI) method of using an effective cracked section property for the transformed concrete area. This comparison shows that both methods are valid only for a limited range of reinforcing ratios.Key words: cracking, crack spacing, crack width, GFRP, reinforced concrete, tension stiffening.

Low-Temperature Compressive Strength of Glass-Fiber-Reinforced Polymer Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 167-172 ◽  
Author(s):  
P. K. Dutta
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Glass Fiber ◽  
Low Temperatures ◽  
High Strength ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

Polymeric composites are relatively inexpensive materials of high strength, in which deformation of the matrix is used to transfer stress by means of shear traction at the fiber-matrix interface to the embedded high-strength fibers. At low temperatures, complex stresses are set up within the microstructure of the material as a result of matrix stiffening and mismatch of thermal expansion coefficients of the constituents of the composites. These stresses in turn affect the strength and deformation characteristics of the composites. This is demonstrated by compression testing of an unidirectional glass-fiber-reinforced polymer composite at room and low temperatures. The increase of compressive strength matched the analytical prediction of strength increase modeled from the consideration of increase in matrix stiffness and thermal residual stresses at low temperatures. Additional compression tests performed on a batch of low-temperature thermally cycled specimens confirmed the predictable reduction of brittleness due to suspected increase of microcrack density. The mode of failure characterized by definite pre-fracture yielding conforms more to Budiansky’s plastic microbuckling theory than to Rosen’s theory of elastic shear or extensional buckling.

Contribution of longitudinal glass fiber-reinforced polymer bars in concrete cylinders under axial compression

2018 ◽  
Vol 45 (6) ◽  
pp. 458-468 ◽  
Author(s):  
Brandon Fillmore ◽  
Pedram Sadeghian
Keyword(s):  
Elastic Modulus ◽  
Glass Fiber ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Steel Bars ◽  
Concrete Cylinders

Contribution of longitudinal glass fiber-reinforced polymer (GFRP) bars in concrete columns under compression has been ignored by current design guidelines. This paper challenges this convention by testing 21 concrete cylinders (150 mm × 300 mm) reinforced with longitudinal GFRP and steel bars in compression. It was observed that GFRP bars could sustain high level of compressive strains long after the peak load of the specimens without any premature crushing. The results of a new coupon test method showed that the elastic modulus of GFRP bars in compression is slightly higher than that of in tension, however the compressive strength was obtained 67% of tensile strength. An analytical model was successfully implemented to predict the axial capacity of the tests specimens and it was found that the contribution of the bars in the load capacity of the specimens was within 4.5–18.4% proportional to the bars reinforcement ratio normalized to the elastic modulus of steel bars.

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