Experimental investigation of fire resistance of axially compressed stainless steel columns with constraints

A series of tests were performed on S30408 stainless steel, including material mechanical property tests at elevated temperatures and fire experiments on rectangular sections of stainless steel columns. Steady tests at elevated temperatures were performed to obtain the stress-strain curves of stainless steel and reduction coefficient of mechanical properties at different temperatures. The test values of the mechanical properties of the stainless steel material are close to those from European specification at temperatures between 100 °C and 700 °C, and their changed trends are basically consistent with temperature. Six axially compressed rectangular columns of stainless steel with constraints were used to investigate the effects of the load ratio, section size and restraining stiffness on the fire-resistance performance of stainless steel columns. The test phenomenon, heating curve, deformation curve and buckling temperature of specimens were determined. The test results show that load ratio and axial restraining stiffness ratio are the key factors for buckling temperature and fire-resistance performance of axially compressed stainless steel columns with constraints. The larger the load ratio and axial restraining stiffness ratio is, the lower the buckling temperature and the worse the fire resistance of stainless steel columns. There are two main types of buckling failure modes of axially compressed stainless steel columns with constraints in fire: the first is flexural buckling and the second is coupling mode between flexural buckling and local buckling. The types of buckling failure modes depend on the cross-section size and the section type of the specimen.