Cyclic Behavior of Lightly Reinforced Concrete Beams

Abstract

The cyclic behavior or seven lightly reinforced concrete cantilever beams is studied as a function of reinforcement ratio, nomina 1 stirrup capacity, stirrup spacing, and ratio of positive to negative reinforcement. An energy dissipation index, Di, is developed to serve as a measure of the performance of reinforced concrete beams subjected to cyclic loading. Di studies. is used to compare the test results of this study with those of four other Recommendations for design are made. Based on the experimental work, the use of a low reinforcement ratio reduces the maximum shear and compressive stresses in beams subjected to cyclic loading, and thus, reduces the rate of degradation. A reduced stirrup spacing and an increased positive to negative steel ratio, AS/As, increases the number of inelastic cycles endured and the total energy dissipated. However, an increased A~/As ratio also increases the induced shear and the energy demand, thus reducing the effectiveness of the increased positive reinforcement. Di appears to provide a consistent measure of beam performance. The analyses based on Di indicate that a decrease in maximum shear stress, and an increase in concrete strength and nominal stirrup capacity will improve the performance of reinforced concrete beams subjected to cyclic loading.