Mechanical properties of GFRP reinforcing bars at high temperatures

This paper presents experimental results of tensile strength tests on glass fibre reinforced polymer (GFRP) bars at high temperatures. These results are a part of a comprehensive study on characteristics of GFRP reinforcing bars from different manufacturers. To represent real construction practices, commonly used #5 GFRP reinforcing bars with nominal diameter of 16 mm are studied. The reinforcing bars are selected from three different manufacturers to study the potential differences of various products. Besides conventional steady-state temperature testing, tensile tests are conducted under transient temperature conditions. In transient tests, specimens are loaded before heat exposure. Temperature ranges from 25 to 500 °C are considered for the steady-state tests depending on the type of bar, and for the transient temperature tests, bars are loaded to between 25 and 70% of the bar's strength at room temperature. The overall conclusion relating to fire performance of GFRP reinforced concrete members is that the three types of GFRP bars that are tested can retain the expected service stress level of 25% of their original tensile strength up to at least 400 °C, and this temperature can be used as the critical temperature in design.