CAPACITY OF RC JOINTS SUBJECTED TO EARLY-AGE CYCLIC LOADING

The influence of cyclic loading applied on T-shape beam-column subassemblies at an early stage of the concrete curing period on the capacity of the joints after the maturing period is experimentally investigated. A series of 20 joints constructed for this purpose were subjected first to an early-age cyclic loading and then retested at the age of 28 days. From the results it is deduced that the early-age loading has significantly influenced the capacity and the overall behaviour of the specimens after the concrete curing period. Specimens subjected to early-age loading 12 or 24 hours after casting exhibited at the age of 28 days peak load values and energy dissipation higher than the ones of the specimens subjected to early-age loading two or seven days after casting, due to the high recoverability of the material at the very early stages of concrete curing period. Emphasis has been placed on the study of the influence of the early-age loading sequence and the slippage of the bars anchorage on the final capacity of the examined specimens. Finally, an attempt is made to assess the damage caused by early-age loading based on the observed stiffness degradation.