## 2 Materials and Methods
### Experimental Setup  
Experimental studies were carried out at the Wind Engineering Laboratory of the Cracow University of Technology [40]. The aerodynamic tunnel allows for a maximum wind speed of about 40 m/s in a measuring area of 10 m in length. The flow can take place in both closed and open circuits. The shape of the measurement space is rectangular and is 2.2 m wide and 1.4 m high.  
A closed-circuit tunnel was used during the test. The first 6 m of the measurement space is intended to create a profile of wind speed and induce turbulent flow. For this purpose, a barrier, and spires of appropriate geometry and spacing were used. The barrier is 200 mm high, and its top edge is irregular and zigzag. The spires are pyramid-shaped.  
Figure 4: The overall dimension of the scaled section model: (**a**) model of box girder SB-8; (**b**) model of truss girder SB-4.5.  
Figure 5: The model of the box girder of the SB-8: (**a**) for experimental tests; (**b**) for CFD simulation.  
Figure 6: The model of the truss girder of the SB-4.5: (**a**) for experimental tests; (**b**) for CFD simulation.  
The width at the base is 300 mm, and the height is 1000 mm. Both elements are located at the tunnel close to the inlet, as shown in Figure 7. The flat urban terrain and turbulent flow are assumed.  
The wind speed measurement was carried out using a set of pressure sensors, as shown in Figure 7. The wind profile was determined independently in the tunnel without the investigated sectional models. Next, the appropriate model was installed inside the tunnel, and the measurements were performed. For these settings, the wind profile was determined at heights between 200 and 700 mm above the floor of the tunnel using six anemometers placed vertically at 100 mm. The height range was determined by the location of the model in the measurement space. The sectional models were placed 350 mm above the tunnel floor. Therefore, the mean value of wind speed \(V_{ref}=17.01\) m/s was assumed at a 400 mm height (mean value of dynamic pressure \(p_{ref}=181.59\) N/m\({}^{2}\)). Turbulence intensity \(I_{V}=12.7\%\) and is the quotient of the standard deviation of the measured wind speed \(\sigma_{v}\) and the mean value of wind speed \(V_{ref}\). The resulting wind profile and turbulence intensity are shown in Figure 8,b.  
Figure 8: Characteristics of (**a**) the wind speed profile for urban terrain and (**b**) the turbulent intensity profile for urban terrain [41].  
Figure 7: Elements of tunnel equipment: (**a**) spires and a barrier for generating turbulent flow; (**b**) vertical rod with pressure sensors for determining the wind profile.  
The coordinate system and the method for defining the wind direction angle \(\theta\) are shown in Figure 9. For the models tested in the tunnel, the aerodynamic forces \(F_{x}\) and \(F_{y}\) and the aerodynamic moment \(M_{xy}\) are measured using a three-component balance based on the electrical resistance of the strain gauges. The fixed \(x\), \(y\), and \(z\) coordinate system is as follows: \(x\)--along the wind direction, \(y\)--across the wind direction, and \(z\)--in the vertical direction; \(W\)--wind direction, with changes from \(-6^{\circ}\)-\(6^{\circ}\) in \(1^{\circ}\) increments.  
The model of the studied girder of the gantry crane was installed horizontally onto the aerodynamic balance. The angle of the wind direction \(\theta\) was changed by rotating the model in the \(xy\) plane. A diagram of the measuring system is depicted in Figure 10.  
To preview the wind speed value in real time, a wind speed sensor with a thermoanemometer was also used to measure the wind speed. The sampling time of the experimental data was equal to 5000 ms.  
Figure 10: Diagram of the measuring system.  
Figure 9: The wind direction and assumed Cartesian coordinate system used in the experiment.