# Experimental Study on the Straw Flexible Space Assembly Flood Control System
## 2 Design of the Flood Control System
### ABAQUS Finite Element Model for the Flood Control System  
As shown in Figure 2, the ABAQUS numerical model components mainly consist of columns, water baffles, and straws. The columns of the oncoming and backing boards of the flood control system are set up. The columns of the oncoming boards only serve to fix the water barrier within a certain range, and do not have a force-bearing role. The columns of the backing boards serve to hold the backing boards in place, and the forces applied to the backing boards are transferred to the columns, so the columns of the backing boards must be reflected in the numerical model. The oncoming and backing boards are five each. The flexible space flood control system focuses on the forces on the water baffles, so the water baffles must be represented in the numerical model. The innovation of the straw flexible space flood control system lies in the addition of a flexible space in the middle of the water baffle. The flexible space is characterised by its ability to be deformed by forces and to assume the role of enhancing the stability of the flood control system, so the flexible space must be reflected in the numerical model.  
There are four types of contact in the numerical model of the flood control system: the two-sided contact between the headwater panel and the flexible space, two-sided contact between the backwater panel and the flexible space, self contact in the flexible space, two-sided contact between the backing board and the column, and tie restraint between the backing boards. The mechanical properties of the contact are mainly defined in the contact properties. Flood control systems generally do not study heat transfer and define the tangential and normal properties of the mechanical properties. The tangential properties are mainly defined according to the coefficient of friction between the materials, which is around 0.2 between aluminium alloy and wood. The boundary conditions of the flexible space flood control system are set without rotation and only fixed as well as directional displacements exist. The main cell type for grid assignment in the gridding of flexible space flood control systems is the C3D8R cell type. The numerical model of the  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline  & **Type** & **Density (KN/m3)** & **Modulus of Elasticity (Pa)** & **Poisson’s Ratio** \\ \hline Water baffles & Aluminum alloy 6061 & 27 & \(7\times 10^{10}\) & 0.34 \\ Column & Q235B & 78.9 & \(20.6\times 10^{10}\) & 0.3 \\ Inclined rod support & Q235B & 78.9 & \(20.6\times 10^{10}\) & 0.3 \\ Connecting rod & EN1.4301 & 78.9 & \(20.6\times 10^{10}\) & 0.3 \\ Bolt plate & Q235B & 78.9 & \(20.6\times 10^{10}\) & 0.3 \\ Straw & - & 4 & \(1.9\times 10^{9}\) & 0.3 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Mechanical property parameters of each component material.  
Figure 1: Straw flexible space flood defending system. (**a**) Composition of flood control system. (**b**) Elevation of the flood control system.  
-flood control system uses a structured sub-grid, which will give the maximum value of the grid density of the solid model. The grid division density also follows the guideline that the greater the stiffness, the greater the density of the grid division should be, so the grid seed interval of the flexible space is 1.5 mm, the grid seed interval of the water barrier is 1 mm, and the grid seed interval of the column is 0.5 mm.