Effect of reinforcement detailing on catenary action in 2-D RC frame

The survivability of a structure under progressive collapse highly relies on its toughness (energy absorption prior to failure). In a 2-D Reinforced Concrete (RC) frame for example, if catenary action is developed, the provision of greater rotational capacity at the support interface would contribute to larger deformations (improving toughness) and longer surviving time of the frame. Previous tests on 2-D RC frames have shown that under large deformations, concrete surrounding the rebar was highly damaged due to cracking, spalling or splitting, reducing the frame capacity. It has also been realised that one way to increase the deformation limit of frames is by allowing more slip or elongation of reinforcement. Based on these two observations, alterations to the conventional reinforcement detailing are devised to improve the frame deformation capacity, i.e. provision of stirrups in accordance to seismic detailing rule to minimise concrete damage and substitution of deformed bars with round bars as longitudinal reinforcement to facilitate greater rotation and slip. Three frame specimens are presented in this paper, the first frame with conventional detailing as the control specimen (FR), the second frame with higher shear reinforcement ratio based on seismic detailing (FR-S), and the last frame with round bars as longitudinal reinforcement (FR-R). Through this study, the effects of modified detailing towards the load resistance and deformation capacity of 2-D RC frames can be quantified.