Influence of both concrete strength and transverse confinement on bending behavior of reinforced LWAC beams

This paper presents an experimental study focused on the structural behavior, regarding not only bending strength but also ductility of reinforced lightweight aggregate concrete (LWAC) beams. The studies about this subject are mainly for normal weight concrete (NWC) and the main design codes consider the prediction of LWAC mechanical properties based on the corresponding values of NWC multiplied by corrective coefficients. However, and since mechanical strength, as well as the stress–strain relation and the distribution of internal stresses, are quite different between those materials, it is necessary to study the influence of the LWAC parameters on both bending strength and ductility of reinforced concrete (RC) elements. Therefore, three types of LWAC were designed, with a specific gravity of 1.9 and with different values of compressive strength; additionally, these were combined with five different ratios of longitudinal reinforcement and three different ratios of transversal confinement stirrups to produce the beams. These beams were tested until bending failure and experimental measurements were performed by specific instrumentation. Results were analyzed and it was concluded that curvature increase with the increase of concrete strength, the ductility indexes are very affected by the tensile reinforcement ratio and the experimentally EII/EIII ratio is different from that predicted by EC2.