Reinforced concrete under cyclic loading

Abstract

In order to contribute to the on going research effort in this field, an experimental working plan with cylinder steel fibre reinforced concrete specimens under compression cyclic loading was carried out. Sets of five specimens were reinforced with conventional transverse reinforcement of 0, 0.57, 1.71 and 4.01 volume percentage of specimen concrete core. To evaluate the fibre reinforcement effect, each of this specimens set was reinforced with 0, 30, 60 and 90 kg/m3 of hooked-ends steel fibres with an aspect-ratio of 60 and a yield strength of 1250 MPa. A total of eighty tests were carried out. The peak stress and the initial elasticity modulus were not significantly changed by fibre reinforcement. The strain at peak stress and the rigidity of the unloading/reloading branches were marginally increased with the increment of the fibre content. The slope of the softening branch was decreased with the increment of fibre content, revealing a significant increase in the energy absorption capacity. The results have pointed out that conventional transverse reinforcement can be partially replaced by appropriate fibre content, without loss of ductility and strength. This replacement could be favorable in zones densely reinforced with hoops and stirrups, like beam-column joints of structures submitted to seismic action.