Experimental investigation on fire resistance of stainless steel columns with square hollow section

• The test results of reduction factors of mechanical properties are close to the code results.
• There exists a temperature gradient alongside the length of the column in fire test.
• The load ratio and eccentricity are key influence factors on the fire resistance of the column.
• There are two failure modes of stainless steel column without axial constraints in the fire test.
• The deformation of thermal expansion is larger for the column without axial restraints in fire.

To study the bearing capacity and failure mechanism of a square stainless steel column in fire, a series of tests were performed on S30408 stainless steel, including 6 material mechanical property tests at room temperature, 16 material mechanical property tests at elevated temperature and fire experiments on 8 square sections of stainless steel columns. Steady tests at elevated temperature were performed to investigate the mechanical properties of stainless steel. The stress–strain curve, elastic modulus, yield strength and the reduction factor of the ultimate strength of stainless steel at elevated temperature were determined, and the test results were compared with the European Codes. The experiments studied the properties of the square section stainless steel columns without axial constraints in fire, which were compressed axially and eccentrically. The failure phenomenon, heating curve, deformation curve and critical temperature of the specimens were obtained. The effects of the load ratio, section dimension and eccentricity on the critical temperature and fire-resistance performance of the stainless steel column were examined. The test results show that load ratio and eccentricity are the key factors for critical temperature and fire-resistance performance of the stainless steel column without axial constraints.