Improving the collapse risk of steel structures with high-performance steel

With the advent of material science, high-performance steel materials have been developed for seismic applications that potentially reduce the earthquake-induced collapse risk of steel frame buildings. The High Yield Point (HYP400) steel is one of those materials that is developed based on thermomechanical control process. Both its yield strength and notch toughness is enhanced compared to conventional seismic-resistant steels. This is achieved through refinement of the microstructural grain size. The application of such material in steel columns facilitates economic design and enhances the collapse capacity of steel moment resisting frames during severe seismic events. This paper first discusses the key aspects of the HYP400 steel and illustrates its potential through detailed nonlinear analyses and earthquake-induced collapse simulations of a steel frame building. The material cyclic hardening prior to the onset of local buckling is characterized on the basis of uniaxial cyclic coupon tests. Finite element studies are then conducted to investigate the pre- and post-buckling behavior of hollow structural section steel columns made of HYP400 steel under various loading histories. A versatile fiber-based deterioration model is then utilized that captures the steel material potential and facilitates computationally efficient collapse simulations. The effectiveness of the HYP400 steel for enhancing the collapse capacity of a steel moment resisting frame is demonstrated through incremental dynamic analysis of a case study steel moment-resisting frame.