| Abstrakt: |
The application of fiber-reinforced polymer (FRP) composites continues to gain wide attention in the construction industry over the last few years. The high ratio of strength to weight, along with corrosion resistance and durability are the main criteria for selecting the most suitable FRP materials. However, exposure to high temperatures affects the FRP performance and subsequently the overall structural performance. The present study sheds light into performance of FRP composites with different matrices as a strengthening material after exposure to elevated temperatures with extended time periods which is unprecedented. To evaluate the effect of elevated temperatures on flexural strength, the concrete beams strengthened with basalt fiber reinforced polymer (BFRP) and glass fiber reinforced polymer (GFRP) sheets in the presence of cement and epoxy adhesives and were subjected to temperatures of 50, 100, 200, and 400 °C respectively for one, three, and to five hours. The results showed the flexural strength values of beams made with cement adhesive were lower than those strengthened using epoxy adhesive at temperatures below 100. For non-strengthened beams, elevating the heat 200–400 °C reduced the flexural strength up 63% to 91% compared to the control beam at room temperature. At 200 and 400 ℃, the strengthened beams made with cement adhesive illustrated higher flexural strength values compared to using epoxy adhesive; this indicates the effectiveness and high tolerance of using cement adhesive for reinforcing beams at extreme heat. Beams strengthened with BFRP sheets and made with either cement or epoxy adhesives had higher flexural strengths compared to non-strengthened or GFRP-strengthened beams at all reported temperatures during the exposure period. The maximum flexural strength of samples exposed to 50 °C and 100 °C belongs to the samples made with BFRP sheets and epoxy adhesive with the strength of 10.5 and 7 MPa, respectively, while the strength of 5.5 and 4 MPa was achieved in samples strengthened with BFRP sheets and cement adhesive at 200 and 400 °C. In order to predict the experimental results, the artificial neural network (ANN) system was used as a reliable method to evaluate and estimate the results, and the results of the numerical analysis showed a reliable estimation of the experimental results. |
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