Size effect of confined concrete subjected to axial compression

LI Zhen-bao(李振宝), SONG Jia(宋佳), DU Xiu-li(杜修力), YANG Xiu-guang(杨修广)

(College of Architecture and Civil Engineering, Beijing University of Technology,
Beijing 100124, China)

Abstract:In order to investigate the size effect and other effects on the stress-strain relationship of confined concrete, 42 specimens with different sizes and section shapes were placed under axial compression loading. Effects of key parameters such as size of specimens, tie configuration, transverse reinforcement ratio, and concrete cover were studied. The results show that for specimens with the same configuration and the same volumetric ratio of the transverse reinforcement, along with the increasing specimen size, the peak stress, peak strain and deformation of the post-peak show a down trend, however, the volumetric ratio of the transverse reinforcement is lowered, the decreasing of the peak stress is accelerated, but the decreasing of the deformation is slow down. For specimens with the same volumetric ratio but different configurations of transverse reinforcement, though the transverse reinforcement configuration becomes more complicated, the peak stress of the large size specimen does not improve more than that of the small size. However, the deformation occurs before the stress declines to 85% of peak stress, and the improvement with the grid pattern tie configuration is much greater due to size effect.

Key words:confined concrete; mechanical property; size effect; configuration type of transverse reinforcement; volumetric ratio of transverse reinforcement; concrete cover