Experimental investigation on uniaxial tensile creep behavior of cracked steel fiber reinforced concrete

摘要

This paper mainly investigates the uniaxial tensile creep behavior of pre-cracked steel fiber reinforced concrete. Hooked-end fiber RC65/60BN with fiber dosage of 80 kg/m(3) was used with normal strength concrete. A suitable tensile creep frame and a pre-cracking test set-up were developed. Cylindrical specimens were pre-cracked at crack opening displacement (COD) of 0.05 and 0.2 mm respectively before the tensile creep test. The pre-cracked specimens were loaded at a load level of 30 % of the maximum pre-cracking load . The specimens were unloaded after 3 months and then reloaded to 60 % of . Time dependent COD were continuously measured by LVDTs under constant temperature of 20A degrees and relative humidity of 60 %. The measured time dependent COD was considered as the summation of three parts, the irreversible part , the instantaneous part and the creep part . It was observed that and the loading level have a great impact on the tensile creep behavior. For the specimens with a pre-cracking COD of 0.05 mm, the maximum creep deformation is almost the same as the initial instantaneous deformation after 3 months loading. For the specimens pre-cracked at 0.2 mm, the damage evolution at the fibre/matrix interface in terms of irreversible crack opening and load level is also discussed. It is interesting to be noted that the creep deformation under load level of 30 % will not introduce extra damage even though the increases.