The concept of seismic-resilient structure has perpetually held significant importance in maintaining the safety and durability of buildings. While most conventional seismic-resistant structures are capable of achieving one key aspect of seismic resilience, namely “robustness”, they often lack the attributes of “redundancy” and “rapidity of repair”. In recent decades, the incorporation of metallic dampers into conventional structures has significantly enhanced their seismic resilience. U-shaped flexural plate (UFP), recognized as one of the most effective metallic dampers, has been widely employed in conventional structures to effectively dissipate input seismic energy. Its innovative application, multiple UFP dissipater (MUD), in the form of a bracing member, not only offers superior strength, stiffness and energy dissipation capacity compared to conventional bracing members but also aligns with the seismic-resilience principle of “redundancy” and provide easier repairability. However, there is lack of comprehensive experimental and numerical research on both UFP and MUD. This research aims to address this gap by focusing on two parts: conducting experimental investigations on four full scale MUD specimens subjected to quasi-static cyclic load at various loading sequences and performing numerical studies on both single UFP and MUD member under monotonic load and cyclic load using ABAQUS.

The experimental tests demonstrate that the MUD is capable of achieving its theoretical capacity and exhibits stable and repeatable hysteretic behaviour. It can dissipate significant amounts of energy, even after the individual UFPs have fractured. MUD has the potential to prevent sudden failure, as reductions in capacity and stiffness are gradual and the failure of an individual UFP does not result in the failure of the entire brace.

In the numerical studies, reliable models of both UFP and MUD were developed and validated against the experimental results. The local deformation behaviour of UFP during rolling motion is discussed in details, including the transformation of the yield area, deformed shape and stress distribution. Furthermore, a parametric study was performed to investigate the effect of UFP geometry, specifically the slenderness ratio and section modulus of the UFP flange, on the amount of flange deflection. Additionally, the relationship between the overall stiffness of MUD and the stiffness of its individual components was analysed.