Shear capacity of additively manufactured stainless steel bolted connections after fire

Additive manufacturing (AM) technology holds significant promise due to its advantages of high precision, high quality, and the capability to manufacture complex structures. Stainless steel (SS) is renowned for its corrosion resistance and aesthetic appeal, making it a widely used material in building construction worldwide. However, the prevalence of fire accidents in engineering can significantly impair the strength of structural components, such as SS columns or connections, potentially leading to structural collapse or partial failure. This study evaluates the mechanical properties of 316 L SS bolted connections manufactured using Selective Laser Melting (SLM) AM after exposure to fire. Eight shear specimens are tested under monotonic tensile loading to assess the influence of various factors, including the temperature, plate thickness, end and edge distances of bolt, and number of bolts, on the connections ' post-fire anti-slip and shear capacities. Material tests conducted prior to shear testing reveal that the ultimate strength of additively manufactured SS sheet increases after exposure to fire compared to conventional SS, although it declines beyond 900 °C. Interestingly, the ductility of the material increases after the temperature reaches 900 °C. The shear tests indicate that the anti-slip coefficient values of the connections after exposure to fire are in the range of 0.339 to 0.563, showing a slight increase compared to room temperature. Analysis of the test results indicates that the Japanese specification provides better accuracy than European specification for estimating the anti-slip bearing capacity of additively manufactured SS bolted connections. Additionally, current specifications may not accurately predict the ultimate bearing capacity of these connections. A more accurate model, which considers the effect of friction force, is developed for predicting the ultimate bearing capacity of additively manufactured SS bolted connections.