Effect of ground-motion duration on seismic performance and collapse probability of high-rise buildings with fluid viscous dampers

While fluid viscous dampers (FVDs) enhance structural seismic performance, their efficacy under long-duration (L-D) ground motions in high-rise buildings remains under-researched. This study investigates the seismic response of a 20-story steel moment-resisting frame in both uncontrolled and FVD-controlled configurations. To evaluate the duration effect, 44 pairs of spectrally matched short- and long-duration ground motions were scaled up to six times the Maximum Considered Earthquake (6MCE). The results demonstrate a fundamental decoupling between transient kinematic demands and cumulative hysteretic degradation. While peak transient deformations, such as inter-story drift, remain relatively insensitive to ground-motion duration, prolonged cyclic excitation drastically amplifies total input energy, plastic hysteretic energy, and structural damage indices. Consequently, L-D motions induce low-cycle fatigue in the uncontrolled baseline structure, reducing its ultimate deformation capacity at failure by approximately 32% and significantly elevating its probability of collapse. However, the integration of FVDs neutralizes this duration-induced vulnerability, maintaining consistent structural collapse probabilities across varying seismic durations. Furthermore, the findings reveal that relying strictly on peak displacement parameters inherently underestimates structural degradation, underscoring the critical necessity of incorporating cumulative energy metrics into the performance-based seismic design of heavily damped high-rise structures.