Constitutive Model of Aluminum under Variable-Amplitude Cyclic Loading and Its Application to Buckling-Restrained Braces

AbstractAluminum has been increasingly used in space, building, and other structures owing to its light weight and high durability. The cyclic plasticity of aluminum is of great importance for the design of aluminum structures in regions with high seismic risk, where extremely large plastic strain loading is involved. For seismic loading, strain amplitudes can vary in a wide range, which makes it necessary to calibrate the plasticity model at the full strain range. This paper aims to present a straightforward approach to accurately evaluating hysteretic properties of aluminum material and structures under variable-amplitude cyclic loading within the full strain range until fracture. In this paper, a new method is proposed to calibrate the generalized Armstrong-Frederick model at the full strain range using only representative mechanical variables of structural aluminum such as yield strength and tensile strength. The newly proposed method is validated at both the material and member levels, respectively, through quasistatic cyclic experiments on double-edge notched specimens and aluminum buckling restrained braces. The validation results show that the proposed method can well describe the cyclic plasticity of aluminum members at the full strain range.