关键词: 冻融循环;混凝土;动态性能;应变率;应力-应变曲线

Abstract: The uniaxial dynamic compression experiments are conducted on frozen-thawed concrete specimens, the effects of freeze-thaw cycles(0, 25, 50 and 75 times) and strain rates(10 -5 s-1、10 -4 s-1 and 10 -3 s-1 ) on the compressive strength , peak strain and stress-strain curve are systematically analyzed .The test results show that the failure model of frozen-thawed concrete at various strain rates are different , and with the increasing of strain rates the fracture section of specimens turns to be more flat and many coarse aggregates are damaged;Under the same number of freeze-thaw, with the increasing of strain rate, the compressive strength increases , the peak stain decreases , the peak of the stress-strain curve shows a trend of moving to the upper left , the ascending branch becomes longer whose slope gradually increases, and the descending branch changes in a steepening trend , which shows obvious brittleness;Under same strain rate , as the increase of freeze-thaw cycles , the compressive strength decreases , the peak stain increases , the peak of the stress-strain curve significantly shifts to the below and right , and the area under the stress-strain curve is decreased , which indicates the energy-absorbing capacity decreases;Based on the experimental data , the compressive stress-strain curve equation considering the effects of strain rate and freeze-thaw cycles is proposed .

Key words: freeze-thaw cycle;concrete;dynamic behavior;strain rate;stress-strain curve