Fire resistance of stainless steel beams with rectangular hollow section: Experimental investigation

• The test results of mechanical properties are close to the code results.
• There are differences in the mechanical properties obtained from two tests methods.
• Load ratio and section height are key influence factors on the fire resistance.
• Failure mode presents in-plane bending for the rectangular tube beam in fire test.

To study the bearing capacity and failure mechanism of rectangular stainless steel beams in a fire, a series of tests were performed on S30408 stainless steel, including 3 material mechanical property tests at room temperature, 45 material mechanical property tests at elevated temperature and fire experiments of 6 rectangular hollow section stainless steel beams with two simply supported ends. Both steady tests and transient tests at elevated temperature were used to investigate the mechanical properties of stainless steel. The stress–strain curve, elastic modulus, yield strength and reduction factor of ultimate strength of stainless steel at elevated temperature were found, and the test results were compared with the results of the European Codes. The experiments studied the mechanism properties of a rectangular hollow section stainless steel beam in fire, and the failure phenomenon, heating curve, deformation curve and critical temperature of the test specimens were obtained. The effects of the sectional dimension and load ratio on the critical temperature and fire-resistance performance of the stainless steel beam were also studied. The test results show that the load ratio and section depth are the key factors for the critical temperature of a stainless steel beam in fire.