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 dif ferent constant-moment zone lengths and two different reinforcement ratios. Closed-loop control was used to obtain post-peak behavior which allowed ad ditional information about the failure mechanisms to be obtained. Results i ndicate that damage localization occurs in the compression zone, and the si ze of the damage zone is constant between specimens of different size (leng th). Evidence of strain-softening behavior could be seen by comparing local and global strains. While the moment-carrying capacity of different size b eams was relatively constant, the average strain at yield and maximum momen t was observed to be slightly dependent on specimen length. The overall duc tility of the beams was dependent on the constant-moment zone length, with larger specimens demonstrating a more brittle response.