Coupling CFD model and FEM model to investigate the impact of debris flows on a low-rise building

This study integrates a hydrodynamic model with a structural analysis model to investigate the behavior of a reinforced concrete (RC) frame building under the influence of various hydrodynamic variables, such as debris flow materials, flow intensity, and flow direction. The impact force generated during the first phase of fluid-structure interaction is significantly larger around (20 ÷ 30) % than that in the steady phase, resulting in a substantially bigger maximum value of bending moment ( M max ) and displacement ( δ ) in every RC column. An increase in flow intensity and solid concentration leads to a larger impact load, resulting in higher values of M max and δ . Furthermore, the flow that passes through the porous exterior of the house poses a greater risk than the flow that affects the non-porous side of the house. By comparison with two Vietnamese standards of bending moment and displacement, all columns of the target building are susceptible to collapse in all scenarios when taking into account the bending moment. Nevertheless, in relation to the key threshold of displacement, the building is likely to remain secure. • The hydrodynamic impact force of debris flood and flow on RC frame buildings may be properly determined using a 3D CFD model, considering building orientation and flow intensity. Early flow interaction with the building results in a peak impact force that is (20 ÷ 30) % higher than at the steady stage. • A FE model is used to simulate maximum bending moment and displacement in the beam and column elements. These value are compared with two threshold values taken in the Vietnamese standard. It is evident that the target building is vulnerable since the maximum bending moment exceeds the critical value, although the maximum displacement does not.