Behavior of GFRP Bars and Sheet Coupons Under Sustained Stress and High Temperatures

Abstract

As part of a comprehensive study on the effects of climate change on the performance of structures containing internal or external FRP reinforcement, tensile tests were performed on FRP specimens under different loading and temperature conditions representing different field scenarios. For steady state temperature testing, specimens were heated to the desired temperature and subsequently loaded to failure. Tensile tests were also conducted on specimens subjected to sustained load or sustained deformation and increasing temperature conditions until failure. A significant difference in the results was observed for the two loading scenarios. For the GFRP bars, steady state temperature tests were conducted up to 250 °C and sustained stress levels varied from 40 to 90% of the bar strength at room temperature. Results showed that GFRP bars experienced about a 60% reduction in strength as the steady state temperature increased to 250 °C. The bars were subjected to a 40% stress level and then exposed to an increasing temperature at a fire rate sustaining the load for about 50 min. Similarly, for the GFRP sheets, steady state temperature tests were conducted up to 150 °C and transient temperature specimens were tested at 40%, 65% and 85% of the GFRP sheet strength at room temperature. The results indicated a sudden drop in the mechanical properties of the GFRP sheets around the glass transition temperature ‘Tg’ in both scenarios. However, beyond glass transition temperature, the specimens were able to retain almost 40% of the strength at room temperature.