Experimental Investigations of Loading Rate Effects in Reinforced Concrete Columns

Seismic loading rates can significantly affect the behavior of reinforced concrete (RC) elements. However, few data are available to quantify these effects. Shaking table tests allow the study of loading rate phenomena; however, they suffer from difficulties in assessing causality (direct assessment of causes on effects) and are expensive to conduct. An alternative is to test individual RC elements by directly imparting high-velocity loading protocols. However, multiactuator setups are necessary to achieve seismically representative loading and boundary conditions, which entails particularly challenging control requirements. This investigation makes use of recent advances in real-time testing hardware to study the effects of loading rates on the structural response of lightly confined RC columns. A pioneering test setup in which three actuators are controlled independently at high velocities was used to test a series of columns until axial collapse. The experimental challenges and column behavior are discussed.