Investigating Behavior of Cantilever Beams of Normal and Lightweight Reinforced Concrete under Cyclic Load

Abstract

Background/Objectives: Investigation the behavior of lightweight aggregate concrete beams and connection under cyclic loading and compare it with the behavior of concrete beam with normal weight. Methods/Statistical Analysis: This study is focused on the experimental investigation of the behavior of the beams constructed of scoria lightweight aggregate concrete. Five samples of cantilever beams are developed; tree of which are made of lightweight aggregate concrete, while two are made of normal weight concrete. In this paper, performance of the plastic hinge in the flexural beams made of lightweight aggregate concrete is investigated based on the stiffness reduction parameters, pinching phenomena, strength reduction, and ductility. Findings: The results showed that beam stiffness, independent from strength, is reduced with increase in the displacement cycles and in the high deformation cycles, pinching phenomenon occurs randomly. Also, strength is not reduced with increase in amplitude of the cycles until reaching displacement ductility 4 and flexural behaviors of normal and reinforced lightweight aggregate concretes are the same value. In deformation cycles with the amplitude of 80mm, equivalent to ductility 4, no significance decrease in the strength is observed in force–deformation curve. With respect to ratio of the shear span to significant depth of the test specimens, the flexural behavior is dominant and the beams endure ductility of greater than 4. It is concluded that the reinforced lightweight aggregate concrete beams with maximum lightweight aggregate size of smaller than 5mm have ductility behavior during the bending, similar to the reinforced normal concrete beams. Application/Improvements: The results demonstrated that in flexural beams, type of concrete (lightweight or normal aggregate) does not have particular influence on the stiffness reduction.