# Influencing Factors of Motion Responses for Large-Diameter Tripod Bucket Foundation
## 3 Experimental Setup and Test Procedures  
### Physical Model  
The geometric details of LDMBF prototypes and the models used in the experiments are shown in Figure 4. As shown in Figure 4a-c, all the prototypes are composed of three bucket foundations with the same diameter of 10 m and the same height 6.75 m and an equilateral triangle connecting frame used to constrain the foundations into a whole. The side lengths are 15 m (equal to 1.5 times the diameter D) for Prototype 1 (Figure 4a), 20 m (equal to 2.0 times the diameter D) for Prototype 2 (Figure 4b), and 25 m (equal to 2.5 times the diameter D) for Prototype 3 (Figure 4c). Three corresponding 1/25-scale stainless steel models were fabricated according to geometric similarity and Froude number similarity. With a 2.0 mm-thick side wall and 1.0 mm-thick top lid, the diameter, height, and mass of every bucket foundation are 0.4 m, 0.25 m, and 5.85 kg, respectively. The weights of the connecting frame welded by stainless steel pipes are 1.2 kg for Model 1 (Figure 4d), 1.4 kg for Model 2 (Figure 4e), and 1.7 kg for Model 3 (Figure 4f). Figure 3: Schematic diagram of the floating state for a single bucket foundation. As shown in Figure 5, the origin \(O\) of the global coordinate system is located at the bottom of structure. The origin \(O\) is located at the centroid at the bottom of the structure. The positive direction of the \(OX\) axis, perpendicular to the line connecting the gravity center of 2\(\#\) and 3\(\#\) bucket foundations, is the direction of incident wave and surge motion. The positive direction of \(OZ\) is set vertically upward and the direction of the heave motion. The \(OY\) axis, the direction of the sway motion, is defined by the corkscrew rule. Tables 1-3 show the pertinent parameters of Prototype 1 and Model 1, Prototype 2 and Model 2, and Prototype 3 and Model 3 in the design and experiments with different drafts, respectively. Figure 4: Prototypes and physical models of large-diameter multi-bucket foundation (LDMBF): **(a)** Prototype 1 with a distance of 1.5 D between one bucket and another bucket, **(b)** Prototype 2 with a distance of 2.0 D between one bucket and another bucket, **(c)** Prototype 3 with a distance of 2.5 D between one bucket and another bucket, **(d)** Laboratory model 1 for Prototype 1, **(e)** Laboratory model 2 for Prototype 2, **(f)** Laboratory model 3 for Prototype 3. Figure 5: Composition of LDTBF. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Items** & \(D\) **(m)** & \(H\) **(m)** & \(\dfrac{H_{d}}{(m)}\) & **S (m)** & \(\dfrac{M_{s}}{(kg)}\) & \(\dfrac{M_{s}+M_{w}(kg)}{I_{max}}\) & **Moment of Inertia (kg m\({}^{\star}\))** & **Gravity Center of** \\ \hline Model 1 & 0.4 & 0.25 & 0.16 & 0.6 & 18.75 & 61.83 & 4.691 & 4.697 & (0,0,0.156) \\ Prototype 1 & 10 & 6.75 & 4.0 & 15.0 & 292.97 & 966.1 & 45.81 \(\times 10^{6}\) & \(45.87\times 10^{6}\) & (0,0,3.89) \\ Model 1 & 0.4 & 0.25 & 0.18 & 0.6 & 18.75 & 69.56 & 5.311 \(\times 10^{6}\) & \(5.317\times 10^{6}\) & (0,0,0.156) \\ Prototype 1 & 10 & 6.75 & 4.5 & 15.0 & 292.97 & 1086.9 & 51.87 \(\times 10^{6}\) & \(51.92\times 10^{6}\) & (0,0,3.89) \\ Model 1 & 0.4 & 0.25 & 0.20 & 0.6 & 18.75 & 77.28 & 5.967 & 5.972 & (0,0,0.156) \\ Prototype 1 & 10 & 6.75 & 5.0 & 15.0 & 292.97 & 1207.6 & \(58.27\times 10^{6}\) & \(58.32\times 10^{6}\) & (0,0,3.89) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Details of the parameters of Prototype 1 and Model 1 evaluated in the experiments.