Strength, Deformation, and Resilience of Cryogenic CFST Columns Subjected to Cyclic Loading

Abstract

According to three aspects of physical mechanisms of cryogenic effect based on tests, a thermo-mechanical sequential coupling meso-scale simulation method was adopted to study the seismic performances of concrete-filled steel tubular (CFST) columns, considering the effects of axial compression ratios (n = 0.2 ~ 0.8), cross-section sizes (D = 200 ~ 800 mm), and temperatures (T = 20 and −60°C), with special focus on the nominal shear strength, deformation characteristic, and seismic resilience of CFST columns. The results demonstrate that the CFST column was prone to brittle failure under high axial compression ratios, particularly at low temperatures. The shear strength of CFST columns first increases and then decreases as the axial compression ratio increases. At ambient temperature, the axial compression ratio threshold is found to be approximately 0.6, while it decreases to 0.4 at low temperatures. The influence of low temperature on the shear strength is diminished as the axial compression ratio increases, but the size effect is enhanced. The yield and ultimate drift ratios are significantly reduced with the addition of axial compression ratio, especially for large-sized columns, as well as the seismic resilience. At low temperatures, the deformation capacity and seismic resilience of CFST columns are markedly reduced, particularly for large-sized columns, with a maximum decrease of 45.2% in ultimate drift ratio while 77.9% in seismic resilience. Based on GB 50936-2014 and JBDPA, the revised limit suggestions for both elastic drift ratio and elastic-plastic drift ratio are given, as well as the revised damage classification standard for CFST columns exposed to low-temperature environments, which can offer references for damage assessment of CFST columns in low-temperature conditions and development of structure repair strategies.

Keywords

drift ratio limit / Low-temperature effect / meso-scale thermo-mechanical coupling simulation / seismic performance / seismic resilience

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