Evaluation of damage development and performance degradation for self-centering shear walls under nonstandard loading histories

This paper evaluates the damage development and performance degradation for self-centering shear walls (SCSWs) subjected to diverse nonstandard loading histories. Sixteen SCSWs with varying concrete strength, self-centering parameters, and stirrup reinforcement ratios are developed and modeled in OpenSees to capture their hysteretic behaviors and energy-dissipating responses. Characteristic damage states are defined to assess and compare damage development for SCSWs under four cyclic loading histories — H1, H2, H3, and H4 — with identical drift amplitudes but different deformation sequences. An energy-based, path-sensitive damage model is employed to quantify damage indices (DI) for SCSWs. The results show a consistent trend of H4 >H3 >H2 >H1 in quantified DI, demonstrating that early application of large drifts significantly accelerates damage accumulation, while improved structural features effectively reduce both damage levels and path sensitivity. In contrast, the Park-Ang model shows limited ability to capture path-dependent damage. Meanwhile, a loading-history sensitivity index (LHSI) is introduced to quantify deformation-history effects, yielding average DI increases of 9.33%, 23.91%, and 40.75% for H2 to H4 relative to the standard loading protocol. A path modification factor is further developed to adjust DI obtained under nonstandard loading paths to align with the suggested damage intervals. Additionally, investigations of residual drifts and equivalent damping ratios confirm the strong influence of deformation history on performance degradation, while increasing the considered structural features can effectively mitigate discrepancies across different loading histories, indicating an enhanced structural performance and damage controllability.