Fire Performance of FRP: Bond of GFRP Bars to Concrete and FRP Strengthened Columns
Standard pullout tests (e.g. 200 mm cubes) with a short embedment length have shown a significant reduction (80% loss at 200 °C) in the bond strength of GFRP bars at high temperatures. More detailed bond behaviour of glass fibre reinforced polymer (GFRP) reinforcing bars has been examined in this study. This study adopted a modified pullout test method in which pullout specimens consisting of GFRP bars embedded in 350 mm (22db) long concrete cylinders are tested at high temperatures. The tests examined the bond degradation under different temperature distributions (i.e. uniform and gradient). The results were compared with the previous pullout tests with 68 mm (4db) embedment length and showed that the pullout capacity of GFRP bars in this test were 3.3, 4, and 2 times higher at 115, 135 and 300 °C, respectively. The results proved the effectiveness of longer embedment length particularly at temperatures below 200 °C. Pullout tests with temperature gradients simulated the bond behaviour of GFRP bars at the unexposed end zones of GFRP reinforced concrete beams or slabs. The results showed that the tensile force in GFRP bars gradually transferred to the lower temperature zones as the heated parts of the bar lost bond with concrete. The results showed that the concentrated forces over a short length of GFRP can trigger concrete splitting and loss of bond even if the GFRP bars still maintain bond with concrete. Providing thicker concrete cover at the end zones of GFRP reinforced members is recommended to enhance fire resistance. Also, a series of approximate and simple numerical models including heat and structural analysis were developed to study the effects of high temperatures on two FRP-wrapped and insulated reinforced concrete columns tested by the National Research Council (NRC) of Canada. The results of finite element models showed less than 5% difference with the experimental results.
URI for this recordhttp://hdl.handle.net/1974/27992
Request an alternative formatIf you require this document in an alternate, accessible format, please contact the Queen's Adaptive Technology Centre
The following license files are associated with this item: