Cyclic Behavior of High Strength Concrete Beams

Four high strength, lightly reinforced concrete beams were fabricated and tested to evaluate member response under severe cyclic loading. Concrete strengths varied from 11 • 31 0 to 12,860 psi with reinforcement ratios of 0.68 and 1 • 02%. Nominal stirrup strength was approximately 170 psi for all specimens. The applied shear stress ranged from 1 45 to 210 psi. The measured energy dissipation capacity for the beams investigated in this study was compared to specimens fabricated with concrete strengths between 4000 and 6000 psi. Based on a statistical analysis of research representing five major studies, recommendations are made to improve the cyclic performance of reinfor·ced concrete beams. The findings show that for beams with similar geometry, strength and load history, an increase in concrete strength improves.cyclic performance. The primary factor influencing cyclic behavior is the applied shear stress. Results also indicate that the use of reduced stirrup spacing and increased beam widths provide improved eye lie performance. Increases in beam width appear to be the most effective means to improve the cyclic performance of beams subjected to severe seismic loading