# Safety Assessment for Upper Part of Floating Crane Considering Minimum Luffing Angle
## 3 Load Condition and Modeling for Structural Analysis  
### Load Conditions  
3.1.1. Load Conditions for Boom  
The present study has reflected the design load of a crane presented in the KR rules (KR: Korea Register of Shipping, 2014). The safe working load of the crane is the maximum weight of a cargo loaded on the attached equipment of the sheave block head, which has been decided for 250 tons and 100 tons. Additional impact load must be the multiplication of the impact load coefficient presented in the KR rules according to the lifting load and types of crane. In the present study, the additional impact load coefficient of 0.25 has been used.  
The self-weight of the crane and attached discharging equipment is 151 tons. The weight of the sheave block and sheave in the loose gear is 14 tons, and the weight of the hook block is 13 tons, which sums up to 27 tons. The friction coefficient 0.02 of discharging has been used. The wind loading F is determined by the following Equation (1).  
\[F=PA\times 10^{-3}\ (\mathrm{kN}) \tag{1}\]  
Here, \(A\) is the sum (m\({}^{2}\)) of the reflected areas of structures and cargos that receive the wind pressure by the wind direction, and \(P\) is the wind pressure, which is calculated by the following Equation (2).  
\[P=\frac{1}{16}C_{h}C_{s}\delta V^{2}\ (\mathrm{Pa}) \tag{2}\]  
Here, \(C_{h}\) is the height factor by the height from the light load line, and \(C_{s}\) is the shape factor that is determined by the shape of various parts of discharging equipment and cargo. \(V\) is the wind velocity (m/s), which must be faster than 16 m/s under the service condition. For the navigation on the restricted area under the stowage condition, the designed wind velocity must be faster than 25.8 m/s. These two conditions have been classified and arranged in Tables 3 and 4, respectively [27].  
As for the inclination angles, which are used to calculate the inclination load of a ship, 5\({}^{\circ}\) of healing angle and 2\({}^{\circ}\) of trim occur simultaneously under the working condition. The heeling angle under the stowage condition is 30\({}^{\circ}\). Under the service condition, the load by the motion of a ship is 0.5 g in the longitudinal direction to the deck and 0.25 g in the traverse direction to the deck. Under the stowage condition, the load is 0.5 g in the longitudinal direction to the deck and 0.25 g in the traverse direction, which is parallel to  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Height** & **Velocity** & **Shape Factor** & **Height Factor** & **Wind Pressure** \\
**(m)** & **(m/s)** & **( C\({}_{s}\))** & **( C\({}_{h}\))** & **(Pa)** \\ \hline
18.1 & 25.8 & 1.2 & 1.1 & 538.7 \\
30.9 & 25.8 & 1.2 & 1.2 & 587.7 \\
42.8 & 25.8 & 1.3 & 1.2 & 636.7 \\
49.2 & 25.8 & 1.3 & 1.2 & 636.7 \\
51.9 & 25.8 & 1.4 & 1.3 & 742.8 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Wind pressure under stowage condition for boom.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Height** & **Velocity** & **Shape Factor** & **Height Factor** & **Wind Pressure** \\
**(m)** & **(m/s)** & **( C\({}_{s}\))** & **( C\({}_{h}\))** & **(Pa)** \\ \hline
18.1 & 16 & 1.2 & 1.1 & 207.2 \\
30.9 & 16 & 1.2 & 1.2 & 226.0 \\
42.8 & 16 & 1.3 & 1.2 & 244.9 \\
49.2 & 16 & 1.3 & 1.2 & 244.9 \\
51.9 & 16 & 1.4 & 1.3 & 285.7 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Wind pressure under service condition for boom.  
the deck. As for the force of the cylinder, four hydraulic cylinders are used for the boom luffing when the boom structure is under the luffing condition. The force of each cylinder is 100 tons with the total force of cylinders as 400 tons.