Experimental Investigation of Extreme Flood Loading on Buildings Considering the Shadowing Effect of the Front Building

Understanding the flood impact dynamics on buildings is still a major challenge, especially considering the built environment. Motivated by the problem of the flood-structure interaction, this study experimentally measured loading conditions onto three-dimensional buildings to investigate flood loading mechanisms considering the shadowing effect. A total of 162 scenarios concerning different values of the initial impoundment depth ($H_i$), aspect ratio of the front building ($\alpha$), relative longitudinal spacing ($\lambda$), and orientation of the front building ($\theta$) were undertaken. Both flood loading mechanisms with and without considering the shadowing effect were discussed elaborately. Results showed that the existence of the front building leads to a dramatic change in flow regime upstream of the rear building, and the shadowing effect highly depends on the development of the flood flow reconstruction. In addition, the shadowing index ${\eta }_F$ was introduced, and it was more sensitive to $\lambda$ than $\alpha$ and $\theta$. When the $\lambda$ was less than 3.5, relative optimal values of $\theta$ were 50°, 45°, and 0° for the scenarios with $\alpha =0.5$, $\alpha =1.0$, and $\alpha =1.5$, respectively. There was a negative dependence of the flood hazard level on the shadowing index. Besides, the modified formula of the maximum flood impact force considering the shadowing effect and fitting formulas between $\lambda$ and $k_s$ were obtained. This research supports the study of flood loading mechanisms and is beneficial to the plan and design of safer building clusters.