Cyclic testing of an innovative self-centering X-braced ductile shear panel

This paper presents an innovative seismic load-resisting component of braced ductile shear panel (BDSP) with self-centering ability. Tension-only nickel-titanium (NiTi) shape memory alloy (SMA) wires installed along the inclined segments are employed to facilitate the self-centering ability. Thin shear panel with pinching hysteretic feature is adopted to decrease the amount of SMA wires, and it provides sufficient lateral bearing capacity and lateral stiffness. A total of eight specimens at one-third scale tests were performed to investigate the hysteretic behavior and re-centering capacity under cyclic loading. The experimental results show that the adoption of SMA wires inside traditional BDSP component realized the desirable self-centering ability and retained moderate energy dissipation capacity with the equivalent viscous damping ratio in the range of 0.124-0.158. Compared to solid shear panel, the employment of slotted shear panel obtained a considerably pinching hysteretic loop and reduced the amount of SMA wires for providing the re-centering ability. The local buckling and damage were primarily focused on the shear panel. The self-centering BDSP specimens were used as replaceable fuse elements for realizing the repairability after an earthquake. The tension field inclination in the solid shear panel ranged from 18 degrees to 33.5 degrees, which was approximately consistent with the main diagonal direction according to observed experimental phenomenon. Furthermore, the surrounding flanges of shear panel did not play an important role on improving lateral strength. The average overstrength factor of the self-centering BDSP specimens was 1.49.