Abstract: Shakedown analysis is an important theoretical basis for structural design and safety assessment under cyclic loading, and it can better reflect the actual carrying capacity of the structure. The material might exhibit cyclic hardening/softening features under cyclic loading, which affects the shakedown of the structure. Taking the commonly used Q235 steel as the research object material, the Q235 sheet is subjected to uniaxial tension and uniaxial symmetric strain controlled cyclic loading tests, and the corresponding stress-strain curve and material mechanical parameters are measured to study its uniaxial tensile properties and cyclic hardening/softening features. The shakedown of the box bearing structure is analyzed numerically using the material parameters measured under above different loading conditions, and the numerical results are compared with the experimental result in the literature. The result show that Q235 exhibits cyclic softening features under the cyclic loading. Compared with the result of physical experiments, the error of the shakedown analysis result obtained by using uniaxial tensile performance parameters is about 25.3%; the error of the result obtained by using cyclic performance parameters is about 6.7%, and the shakedown analysis result considering cyclic softening effect is closer to the result of physical experiment.

Key words: cyclic hardening/softening, cyclic stress-strain curve, shakedown limit load, box bearing structure, Q235