## 3 Materials and Methods
### Preliminary Design  
#### 3.3.1 Materials and Member Selection  
Hot-rolled structural steel is the main material for the structural members in this project. Both hot-rolled universal beams and columns are considered. Customised welded steel sections are also applied, while available steel sections cannot satisfy the required machinal properties. In practice, the hot-rolled steel sections are required to be prepared complying with AS/NZS 3679.1:2016 [92]. Welded I sections should follow AS/NZS 3679.2:2016 [93]. However, in the framework of this study, the preset material and section properties in Strand7 are used for simplification in numerical simulation. Figure 34: C# scripts for colour code conversion from hexadecimal format to RGB triplet. Figure 35: Grasshopper scripts for output line models of other structural components for Strand7 analysis. I sections have superior strength for bending due to their wide flanges and have excellent performance under shear force due to their webs, making them highly efficient for load-bearing structures with long-span-like bridges. High-strength bolts are assumed to be applied for member connections, and the joints are assumed to be rigid for simplified design. Steel beams are also capable of prefabrication and modular construction, which can minimise the structural imperfection and enable lower transportation costs for the equipment among different projects [94]. In addition, there have been studies confirming the feasibility of reusing steel construction materials, which is beneficial to not only control the marginal cost but also meet the sustainability requirements for heavy equipment such as the OMSS, which is mainly constructed of steel, but well-built BIM technology is required to ensure the safe operation of the OMSS over its multiple lifecycles [95]. The preliminary structural member selection and corresponding beam type setup in Strand7 were conducted before more detailed analysis, as shown in Table 3.  
Figure 36: Line model and layers baked from Grasshopper. Figure 37: Strand7 model import settings: (a) Strand7 button menu; (b) model import window. Figure 38: Rhino file properties read by Strand7: (**a**) Rhino colours to Strand7 beam properties; (**b**) Rhino layers to Strnad7 groups. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & **Structural Member** & **Beam Type** & **Initial Member Size** \\ \hline \multirow{5}{*}{\begin{tabular}{c} Primary Arch \\ (Main Arch) \\ \end{tabular} } & Truss Chords & Truss & 460 UB 82.1 \\  & Truss Bracings & Truss & 410 UB 59.7 \\  & Truss Verticals & Truss & 410 UB 59.7 \\  & Chord Transverse Bracings & Beam & 310 UB 46.2 \\  & Web Transverse Bracings & Beam & 310 UB 46.2 \\ \hline \multirow{5}{*}{\
\begin{tabular}{c} Secondary Arch \\ (Sub-arch) \\ \end{tabular} } & Truss Chords & Truss & 360 UB 56.7 \\ \cline{2-3}  & Truss Bracings & Truss & 460 UB 82.1 \\ \cline{2-3}  & Truss Verticals & Truss & 460 UB 82.1 \\ \cline{2-3}  & Chord Transverse Bracings & Beam & 310 UB 46.2 \\ \cline{2-3}  & Web Transverse Bracings & Beam & 310 UB 46.2 \\ \hline \multirow{5}{*}{
\begin{tabular}{c} Primary Girder \\ (Main Girder) \\ \end{tabular} } & Truss Top Chords & Truss & 410 UB 59.7 \\ \cline{2-3}  & Truss Bottom Chords & Truss & 410 UB 59.7 \\ \cline{2-3}  & Truss Bracings & Truss & 310 UB 46.2 \\ \cline{2-3}  & Truss Verticals & Truss & 310 UB 46.2 \\ \cline{2-3}  & Top Transverse Bracings & Beam & 250 UB 37.3 \\ \cline{2-3}  & Web Transverse Bracings & Beam & 250 UB 37.3 \\ \cline{2-3}  & Bottom Transverse Bracings & Beam & 250 UB 37.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Preliminary member selection and beam type setup for each structural component. An Excel spreadsheet was established based on AS 4100:2020 to select the proper section size with respect to the member axial force and bending moment calculated in Strand7 [7]. The details of the excel spreadsheets are shown in Figures 39-44.