Effect of strain rate on compressive behaviour of high-strength concrete after exposure to elevated temperatures

• Effect of strain rate on compressive behaviour of pre-heated HSC was investigated.
• HSC prisms were heated up to 20, 200, 400, 600 and 800 °C.
• Pre-heated prisms were axially loaded at strain rates of 10−5, 10−3 and 0.067 s−1.
• Dynamic increase factors of pre-heated HSC are proposed and discussed.

The effect of strain rate on the compressive behaviour of high-strength concrete (HSC) after exposure to elevated temperatures was experimentally investigated. 45 HSC prisms were heated up to 20, 200, 400, 600 and 800 °C. The pre-heated prisms were then axially loaded at a quasi-static strain rate of 10−5 s−1 as well as two aftershock dynamic strain rates of 10−3 and 0.067 s−1, respectively. The test results indicate that the higher the temperature and strain rate are, the larger the number of cracks and fragments will be. Both the residual compressive strength and elastic modulus of HSC decrease with the increase of elevated temperatures, whereas they increase as the strain rate increases. Moreover, the peak strain is enhanced by the elevated temperature but hardly influenced by the strain rate. Finally, the stress–strain relationship and dynamic increase factor (DIF) of HSC after exposure to elevated temperatures are proposed.