Abstract:
In view of the freeze-thaw damage phenomenon of concrete structures in the alpine region and the characteristics of shear failure of concrete structures, the shear tests on concrete are carried out by using a large multifunctional dynamic and static electro-hydraulic servo triaxial testing system and a shear box device. The effects of normal stress, strain rates and freeze-thaw cycle times on the shear strength of concrete are studied and analyzed in this paper. By defining dimensionless sensitivity function, the sensitivities of the normal stress, strain rate and freeze-thaw cycle times to the shear strength of concrete are compared, and the sensitivity of each influencing factor is ranked. The analysis results show that: ① The shear strength of concrete increases with the increase of the normal stress. Its testing curves can be divided into three stages, i.e. linear rising stage, nonlinear rising stage and stable stage. The free water in the micro-cracks and pores of concrete is one of the important factors leading to the increase of the concrete shear strength with the increase of strain rate. The increase of concrete porosity is the reason that the shear strength of concrete decreases with the increase of the freeze-thaw cycles. ② When the freeze-thaw cycle times of concrete are not higher than 50 times. The normal stress is not more than 35 MPa and the loading strain rate is 10
-5/s~10
-3/s, the freeze-thaw cycle times have great influences on the sensitivity of the shear strength of concrete. The normal stress of concrete has little effect on the sensitivity of the concrete shear strength, while the strain rate has the least effect on the sensitivity of the concrete shear strength.