The damage-based inelastic displacement ratio for performance-based design of fully self-centering systems under pulse-like near-fault earthquake ground motions

In this investigation, the damage-based inelastic displacement ratio (IDR) for fully self-centering (SC) systems with flag-shaped hysteresis behavior is determined under pulse-like earthquake ground motions to use in performance-based design theory. Pulsive earthquakes are known as dangerous natural phenomena due to the location of structures in the vicinity of the fault with forward-directivity and high-velocity amplitude features, which expose the system to high risk. Before this, the IDRs were obtained based on constant-ductility and strength reduction factor intensities for designing new and evaluating existing structures with SC behavior. However, the issue could be extended to an energy-based theory using the Park-Ang damage model as a popular index among researchers, with the ability to consider record amplitude, frequency content, and duration. Therefore, the damage-based IDR was determined under 252 pulse-like records with 126 pairs at four damage levels, 30 periods of vibration, four ultimate ductility factors (mu u), four stiffness hardening ratios (alpha), and three dissipative energy factors (beta n) by conducting comprehensive nonlinear dynamic analysis. Then, the influence of the mentioned parameters on obtained IDRs is evaluated to propose a robust equation for estimating target displacement in these systems. Statistical results illustrate that the approximate equation based on normalizing the structural period to the predominated period can predict the target displacement compared to achieved ones from direct time-history analysis, where the difference between estimated and mean target displacements is below 15%.