Investigations on the effect of roof types on wave impinging on a building: A hybrid experimental-numerical approach

Numerous efforts have been made to estimate the tsunami wave loads on structures, particularly box-shaped buildings (flat-roofed). As buildings have different types of roofs, insights into their respective wave flow mechanisms are important especially for the overtopping case. This study, therefore, focuses on the effect of roof types on tsunami-like waves impinging on a building. Through a series of wave flume experiments and numerical simulations, wave loads exerted on the front and back faces of a typical gabled-roof building were measured and compared with that of a box-shaped building. Results showed that the roof eaves caused the wave reflection and increased the upstream water depth, leading to an increment in maximum front face force up to 11% relative to the case of flat roof. Howbeit, less wave overtopping effect was demonstrated, thereby inducing a lower wave impact at the back of the building with a gabled roof. A ratio comprising the maximum flow depth and the story height of a building was then proposed, where the effect of gabled roof on the resulting maximum horizontal force was found to be insignificant to a ratio below 0.6. Finally, empirical equations to predict the maximum wave pressure on a building's front and back faces were formulated, which provide practical information for the design of a tsunami-resilient coastal building.