Second-Order Effects in Lightweight Aggregate Concrete Slender Columns

This paper covers the analysis of the behavior of columns made of LWAC (Lightweight Aggregate Concrete), which can be used as a substitute for normal-density concrete. This work presents an experimental research program focused on second-order effects in slender elements (λ = 74) made of LWAC and normal-density concrete tested under eccentric load. Elements with two ratios of longitudinal reinforcement (0.9%, 2.3%) were considered. Despite the similar compressive strengths of the concrete, the significantly different moduli of elasticity of the two types of concrete caused the lightweight concrete columns to show higher displacements, leading to their lower load bearing capacity. This disproportion was more pronounced for low longitudinal reinforcement. In the second part of this experiment, the behavior of the columns was simulated using models taken from the literature. The analysis showed that the models often do not accurately predict the elastic modulus or LWAC limit strain of concrete, so when trying to predict the behavior of this type of element accurately, these parameters should be determined experimentally.