Behaviour of fibre reinforced beam-column sub-assemblages under reversed cyclic loading

The potential of usage of steel fibre reinforced concrete (FRC) in structural components like beam-column joints under cyclic loading has been explored in the present study. Three different types of beam-column sub-assemblages, i.e. (i) with normal concrete, and designed according to Indian Standard and Eurocode including seismic joint detailing (Type A), (ii) adopting modified reinforcement detailing but including FRC and, (iii) designed for target joint failure (Type B) as well as flexural failure (Type C), have been considered. The specimens were experimentally investigated under repetitive reversed cyclic loading. Performance of the specimens under cyclic loading is evaluated in terms of failure mode, energy dissipation, strength degradation, shear deformation, strain development in reinforcement, etc. It has been found that longitudinal reinforcements of FRC specimen were found to be yielded at the face of the column and joint failure was completely avoided. At a drift level of ±5%, both the code based ductile specimens (Type A) showed a strength deterioration of 30% after the third cycle whereas Type B and Type C specimens experienced 10% and 20%, respectively. The present study has also brought out that all specimens of Type B performed better than Eurocode based reference ductile (Type A) in terms of energy dissipation. It is also observed that flexural specimens (Type C) were able to dissipate higher seismic energy than that obtained from Indian Standard based full ductile specimen (Type A). The results and observations of the present study would help in understanding the behaviour of critical regions of structures such as beam-column sub-assemblages and the efficacy of usage of FRC in those joints under cyclic loading.