Localization and size-dependent response of reinforced concrete beams

This paper describes an experimental investigation to determine whether the flexural response of reinforced concrete beams is size (length) dependent. Sixteen normal- and high-strength concrete beams were tested with four different constant-moment zone lengths and two different reinforcement ratios. Closed-loop control was used to obtain post-peak behavior which allowed additional information about the failure mechanisms to be obtained. Results indicate that damage localization occurs in the compression zone, and the size of the damage zone is constant between specimens of different size (length). Evidence of strain-softening behavior could be seen by comparing local and global strains. While the moment-carrying capacity of different size beams was relatively constant, the average strain at yield and maximum moment was observed to be slightly dependent on specimen length. The overall ductility of the beams was dependent on the constant-moment zone length, with larger specimens demonstrating a more brittle response.