EXPERIMENTAL STUDY ON THE AXIAL COMPRESSION BEHAVIOR OF PREFABRICATED RC COLUMNS LINKED AT MIDDLE REGION AT DIFFERENT STAGES OF CONSTRUCTION

Five prefabricated RC columns linked at the middle region and two monolithically casted RC columns were tested under axial compression loads to investigate the influence of linkage site curing time on the axial compression performance of specimens at different stages of construction. The results indicate that obvious differences in axial compression performance for prefabricated RC columns exist at different construction stages. The axial strength of the prefabricated RC column without casting concrete at the linkage site is 46.2% that of the monolithically casted RC columns. After concrete is cast, the axial strength of prefabricated RC columns increases with the increase of curing time for the linkage site. When the curing time for the linkage site is 28 days, the axial strength of the specimen is 87.9% that of the monolithically casted RC columns. Due to the pressure exerted at the cone-shaped cross section of the upper columns, the linkage site of the prefabricated RC columns expanded laterally, which gave rise to the confinement of the concrete by the stirrups. The failure modes of the specimens show distinct plastic characteristics compared with those of the monolithically casted RC columns. The mechanical analysis of axial compression for prefabricated RC columns was carried out and a calculation method for axial strength is proposed. Calculated results show good agreement with test results. This paper can be referenced for the engineering practice of prefabricated RC structures.