Numerical investigation of cyclic behaviour in H-shaped stainless-steel beam-columns

This study conducts a numerical investigation into the cyclic performance of H-shaped stainless steel beam-columns under seismic loading. Numerical models were developed and validated using experimental data from H-shaped carbon steel beam-columns subjected to cyclic bending. These models showed high predictive accuracy, with a 7.5 % margin when comparing end moments and rotations. Through the finite element approach and Taguchi method, key parameters were analysed including column length, stiffener spacing, material classification, load ratio, stiffener thickness, and number of local buckling modes. The results highlight austenitic stainless steel's exceptional deformation capacity, with enhanced elongation at fracture and superior post-yield strength compared to carbon steel. With a ductility ratio of 19.09 under a 0.4 load ratio, it surpasses ferritic and duplex stainless steels. This demonstrates superior seismic energy absorption and enhanced energy dissipation through broader hysteresis loops. Duplex stainless steel, with 30.5 % higher yield stress than austenitic grade, exhibited narrower hysteresis loops and earlier local buckling, balancing high cyclic strength with moderate ductility. This makes it ideal for stiffness-critical applications under intense cyclic demands. Ferritic stainless steel, though stronger than carbon steel, showed 50 % lower elongation than austenitic steel, with higher brittleness and inferior energy dissipation compared to duplex steel. The study underscores the role of axial load ratios in governing failure modes and deformations. These findings are pivotal for advancing design codes and enhancing structural resilience in earthquake-prone regions. They emphasize the inclusion of stainless steel in seismic design standards, addressing current limitations due to insufficient research on its cyclic behaviour.