Ductility-Targeted Design of Cast Steel Replaceable Modular Yielding Links and Their Experimental Validation through Large-Scale Testing

The application of steel castings in earthquake engineering has increased significantly in recent years, and steel casting technology has been proven as a viable solution for the design and development of energy dissipative yielding elements. The first-generation of cast steel replaceable modular yielding links were recently proposed as an off-the-shelf energy dissipative product line for use in steel eccentrically braced frames (EBF). The performance of the links was validated through an extensive full-scale experimental program. These links featured a design approach in which the effective length of all links across the product line was identical. As a result of this design approach, a wide range was observed in the ductility capacity, with the smaller- to medium-capacity links achieving larger rotation capacities than the larger-capacity links. This paper presents the design and experimental validation of an alternative design of cast steel replaceable yielding links where, rather than ensuring equal length across the product line, a similar link ductility capacity is targeted for all link sizes. The new cast steel links with targeted ductility capacity are presented, and the performance of two link sizes is validated through large-scale experiments to confirm that the proposed design achieved the targeted design ductility. Each link size was tested twice: once as a standalone element and once as part of a one-story EBF system that imparted a large axial load to the link. Based on the results, the effect of axial load on the performance of EBF links is discussed.