Study on mechanical properties of (1 PVA fiber +1 Steel fiber) PS-ECC under the coupling effects of elevated temperature and dynamic loads

摘要

The coupling effect of temperature and impact loads can cause the concrete strength to decay and lead to the failure of the structure that cannot reach the designed load-bearing strength. In this study, the evolution laws of dynamic compressive strength, dynamic increase factor (DIF), and absorbed energy of (1% polyvinyl alcohol [PVA] fiber +1% steel fiber) PS-ECC (engineered cementitious composite) were obtained by a split Hopkinson compression bar test. The conclusions can be concluded: the dynamic compressive strength, DIF, and absorbed energy of PS-ECC largely show a tendency to decrease with increasing temperature; however, the recovery effect occurs at 200℃ due to the accumulation of steam inside the specimen to counteract the impact force. Then, 200℃ becomes a threshold value, and the sensitivity of PS-ECC to strain rate shows a steep drop when the temperature exceeds 200℃. Compared to 200℃, the growth rate of dynamic compressive strength, DIF, and energy absorption capacity from strain rate 50-80 s~(-1) decreases by 50.65, 55.24, and 45.71% at 300℃, the growth rate decreases by 55.87, 56.5, and 48.45% at 400℃. The impact energy absorption of PS-ECC was provided mainly by PVA fiber. The energy absorption of PS-ECC is almost the same at 300 and 400 C for the same strain rate due to PVA fiber burning disappears.