Laboratory and Numerical Experiments on Flood Impacts on Buildings

In recent years the raising number of urban floods connected to climate change highlighted the importance of investigating the action of floods on building and urban systems. In fact, the identification of hydrodynamic loads produced by the floods can improve the building safety design, the effective hazard assessment and the emergency management. We propose an experimental and numerical study to investigate the actions generated by floods with different characteristics (depth, velocity and incidence angle) on masonry buildings, typical of many European and Italian urban fabric.

The experimental study was carried out in the 50-m long flume of the Laboratory of Hydraulics and Maritime Construction of the Polytechnic University of Marche. A masonry bay with scale 1:10 was reproduced with steel structure and scaled masonry infill walls, characterized by scarcely permeable surfaces. Due to the large discharge to be reproduced in the flume, the effect of the flow hitting the building was obtained with the motion of the building inside the water body [1]. Different flows were reproduced in the laboratory, by varying the flow velocity, the water depth and the angle of incidence on the building. To quantify the action of the flow on the building, the relative pressures at significant locations of the building was measured. The comparison of flow characteristics with the corresponding actions shows that the load on the building depends on the flow characteristics in different manner for the frontal, lateral and rear walls.

Numerical simulations reproduced the experimental conditions, using the CFD commercial software Ansys Fluent^©. First, the experimental condition was exactly reproduced, moving the building in the water body at rest. Additional simulations reproduced the same geometry of the experiments, with the fixed building subject to a steady flow. Comparison of numerical results revealed the differences between the experimental configuration (a moving building inside a water body) and the real case (a fixed building hit by the water flow). The numerical simulations also provide further information of the hydrodynamics around the building.

References:

[1] M. Postacchini, G. Zitti, E. Giordano, F. Clementi, G. Darvini, S. Lenci. Flood impact on masonry buildings: the effect of flow characteristics and incidence angle (Submitted to Journal of Fluids and Structures)