Fire-resistant design of stainless steel-concrete composite beam considering slip of stud connector

Stainless steel-concrete (SSC) composite beams have gained attention in structural engineering in recent years. However, there is currently no fire-resistant design approach proposed specifically for SSC composite beams. The current fire-resistant design approach for composite beam is based on the material behavior of carbon steel, which may not accurately reflect the behavior of SSC composite beams due to the significant differences in material properties. In particular, the nonlinear constitutive characteristic and greater coefficient of expansion of stainless steel compared to carbon steel can impact the fire resistance of SSC composite beams. The shear behavior of connectors is also crucial in composite beams, with the shear behavior of connectors being of particular importance. Towards clarifying the shear behavior of the stainless steel stud connectors, this paper conducted push-out tests and finite element analyses. The load-slip curves of the S30408 stainless steel stud connectors with different diameters (13 mm, 16 mm, 19 mm, 22 mm) at different temperatures were obtained. Subsequently, comprehensive parameter analyses of the fire resistance of the S30408 SSC composite beam based on the load-slip curves of the stud connectors were conducted. Based on these analysis results, the essential modification of the formula of ultimate bearing capacity at elevated temperature of the Chinese national standard GB 51249-2017 was conducted. Moreover, a modified fire-resistant design approach was proposed to predict the critical temperature of the S30408 SSC composite beam under the ISO-834 standard fire, and the approach was assessed by existing test results.