Effects of horizontal pulse-like ground motions on a full-scale two-story RC frame with viscous fluid dampers: Shaking table tests

Near-fault pulse-like ground motions impose unique seismic demands often overlooked in conventional design, yet experimental evidence on the full-scale performance of viscous fluid dampers (VFDs) under such excitations remains scarce. This study presents full-scale shaking table tests on a two-story reinforced concrete frame equipped with VFDs, subjected to both pulse-like and non-pulse-like ground motions. The results reveal that pulse-like excitations markedly amplify damper demands, with displacements up to four times larger than those induced by non-pulse-like motions. Although damper forces remained within design limits, the increased displacements under strong pulse-like excitations indicate potential vulnerabilities. Structural acceleration responses were also significantly amplified, particularly on upper floors, with increases reaching 109.76 %. Directional differences were evident: in the damper-equipped direction, VFDs effectively stabilized displacements and reduced inter-story drifts by 76 %–120 % compared with the seismic-resistant direction, corresponding to an improvement of 2–4 acceleration intensity levels. These findings highlight both the sensitivity of damped systems to strong velocity pulses and the substantial contribution of VFDs in mitigating displacement demands under near-fault conditions. Despite inherent limitations of the test program, this study provides rare full-scale evidence on VFD performance under near-fault pulse-like ground motions, offering valuable insights to guide damping strategy optimization and seismic design in fault-adjacent regions. • Investigates the seismic response of a full-scale two-story RC frame with VFDs through shaking table tests. • Analyzes the influence of pulse-like ground motions on the dynamic behavior of VFDs. • Quantifies response differences between damper-equipped and resistant directions under pulse-like ground motions. • Provides insights for the seismic design and retrofit of damped structures in near-fault regions.