Megathrust earthquakes, such as the 2010 Maule and 2011 Tohoku events, have underscored the destructive potential of long-duration ground shaking, which poses unique challenges for structural systems and carries significant societal implications. Traditional seismic design prioritizes peak ground motion parameters, often overlooking the cumulative damage effects associated with prolonged shaking. This study examines the influence of ground motion duration on the seismic performance of reinforced concrete (RC) shear walls using controlled laboratory experiments. Three identical half-scale, flexure-dominated RC shear walls—designed according to pre-2010 Chilean seismic provisions—were subjected to in-plane cyclic loading under distinct displacement protocols. Two specimens were driven by nonlinear OpenSees time-history analyses reproducing (1) long-duration subduction motion and (2) spectrally equivalent short-duration motion; a control specimen followed a conventional symmetric cyclic protocol. Damage progression, energy dissipation, and failure modes were monitored via hysteresis loops, crack mapping, and displacement capacity measurements. Long-duration histories accelerated crack proliferation, concrete cover spalling, and reinforcement buckling, yielding lower ultimate displacement capacities compared to both short-duration and standard protocols. The short-duration specimen’s test was truncated at μ = 6 due to lateral frame instability, underscoring the need for robust test setups. Findings support integrating duration-sensitive loading sequences into experimental and design practice to capture cumulative low-cycle fatigue and improve seismic resilience of RC shear walls.
Lopez et al. (2026) studied this question.