Material properties of YSt 310 steel tubular columns under extreme loading conditions

Steel tubular columns have emerged as one of the most sought-after solutions for infrastructure development due to their exceptional mechanical properties. The properties include resistance against bi-axial bending, axial compression and also better aesthetic appearance. YSt 310 cold-formed tubular sections are widely used across various Indian infrastructure projects. Given their extensive application, it is crucial to understand the material characteristics of YSt 310 under extreme loading conditions for designing structures that can withstand dynamic, blast, and impact loads. This study focuses on the material characterization of YSt 310 steel through coupon tests conducted at various strain rates (from 3 × 10⁻⁴/s to ∼1400/s), temperatures (from 27 to 600 °C), and notch radii (2, 1.5, and 1 mm). High strain rate tests are performed using tensile split Hopkinson pressure bar (TSHPB) and split Hopkinson pressure bar (SHPB). The Johnson-Cook (JC) constitutive and damage model parameters are evaluated alongside Cowper-Symonds (CS) model and presented. Notably, the study proposes modifications to the JC model to improve its predictions, specifically at elevated temperatures. The findings are compared with the strain-based acceptance criteria in ASME B&PV Code, Section III. The experimental findings revealed that the plastic stress demonstrated a positive sensitivity to higher strain rates, while an increase in temperature resulted in negative sensitivity. From the experiments, it was observed that fracture strain decreased with an increase in strain rates, and there is a marginal influence of temperature on fracture strains.