Experimental Investigation of Cyclic Degradation of Light RC Beams under Periodic Loading

Structural elements and systems experience a decrease in strength and stiffness throughout their lifetimes, called degradation. One of the most common types of degradation in RC (Reinforced Concrete) structures is the cyclic degradation caused by earthquakes. Structures that experience one or more earthquakes during their lifetime, experience a degree of degradation that affects their seismic response to subsequent earthquakes. Existing numerical models take into account the cyclic degradation of an earthquake, but many of these models neglect the effects of degradation caused by previous earthquakes; Recent studies show that this degradation has significant effects on the response of structural elements. In this study, the cyclic degradation of RC beams and their impact on the post-earthquake behavior of the beams is investigated experimentally. For this purpose, 12 RC beams are manufactured and subjected to displacement-control loading. Periodic loading with uniform amplitude is used to simulate the earthquake cyclic degradation. Three levels of slight, moderate and extensive degradation are selected to investigate the effect of cyclic degradation on the post-earthquake behavior of elements. After the experiment, the results of the hysteresis diagrams, strength degradation and energy absorption of the specimens are presented and discussed. The results of this study show that as the level of cyclic degradation increases, the energy absorption of RC beams decrease; Especially in the extensive level of degradation, the energy absorption of the beams is reduced by more than 40%.