Impact of permeability on the structural response of mid- and high-rise RC wall buildings under sequential earthquake-tsunami loading

Sequential earthquake-tsunami events are characteristic of subduction zone environments, where rapid coastal urbanisation and population growth increase exposure and risk. When horizontal evacuation is not feasible, vertical evacuation (VE) using suitable buildings may represent the only viable life-safety strategy. However, the structural response of buildings to tsunami loading remains highly dependent on permeability assumptions, which govern how water penetrates the structure and redistributes forces among structural elements. This study investigates the impact of permeability on the structural response of mid- and high-rise reinforced concrete (RC) wall buildings subjected to sequential earthquake-tsunami loading. Two representative Chilean RC wall buildings of 9 and 17 storeys are modelled using three-dimensional OpenSees models with MVLEM-3D macro-elements to represent the shear walls. Three permeability assumptions: impermeable, partially permeable, and fully permeable are evaluated through ten earthquake-tsunami record pairs derived from the same physical source. Key engineering demand parameters, including inter-storey drift, wall shear demand, and fibre strain, are assessed. Results show that earthquake response is primarily governed by flexural-compressive mechanisms, whereas tsunami response is dominated by shear. Structural damage is highly sensitive to permeability assumptions, with the fully permeable condition consistently producing the most critical response due to increased out-of-plane wall loading. The 9-storey archetype is found to be particularly vulnerable to tsunami-induced shear demands, frequently exceeding its capacity, whereas the 17-storey archetype exhibit comparatively better performance due to increased stiffness, wall thickness, and self-weight. The results highlight the importance of permeability assumptions and three-dimensional modelling in evaluating RC wall buildings for sequential earthquake-tsunami hazards and their potential use as vertical evacuation shelters.