## 6 Study 3: Large-Scale Open-Jet Testing for Cladding Design in High-Rise Buildings
### Objectives of the High-Rise Building Study  
This investigation aimed to precisely reproduce the distribution of wind-induced pressure surrounding a tall building, through experimentation on a large-scale model at a high Reynolds number [57]. The primary objective was the adept design of cladding components, glass, and fenestration for high-rise structures to mitigate damage from severe wind occurrences. Emphasis was placed on comprehending the impacts of aspect ratio and scale effects on pressure magnitude and distribution [57]. The aerodynamic testing encompassed two distinct aspect ratios (width-to-depth ratios of 0.67 and 1.5) to gauge the significance of structural dimensions on wind loading. Comparative analysis of findings from this open-jet testing study with those from a smaller-scale study was conducted, to underscore the criticality of testing at elevated Reynolds numbers. Non-dimensional pressure contours were generated for all facets of the structure. An examination of peak and fluctuating pressures was undertaken to grasp the influence of the Reynolds number on the aerodynamic loads responsible for damage to cladding, glass, and fenestration of tall buildings in the face of extreme winds. A three-dimensional experimental model, scaled at 1:50, was crafted to delve into the aerodynamic behaviour of the building. The subject of this study is an envisaged timber high-rise slated for construction in Chicago, USA. The dimensional specifications for the full-scale structure are as follows: a height of 121 m, a width of 36 m, and a depth of 24 m [77]. A rigid model of the building was constructed using plywood to \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Case 1**} & \multicolumn{2}{c}{**Case 2**} & \multicolumn{2}{c}{**Case 3**} & \multicolumn{2}{c}{**Case 4**} \\ \cline{2-9}
**Zone** & **Cp** & **Angle** & **Cp** & **Angle** & **Cp** & **Angle** & **Cp** & **Angle** \\ \hline \(1_{\text{W}}\) & \(-0.865\) & \(0\) & \(-0.400\) (54\%) & \(0\) & \(-0.478\) (45\%) & \(0\) & \(-0.336\) (61\%) & \(270\) \\ \(1_{\text{L}}\) & \(-0.906\) & \(0\) & \(-0.362\) (60\%) & \(180\) & \(-0.436\) (52\%) & \(180\) & \(-0.335\) (63\%) & \(270\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The highest average “net” minimum pressure coefficients for Zone 1 across all test angles. These net pressure coefficients indicate the aggregate force exerted on the structure when subjected to wind-induced loads acting on both the roof and the attached solar panels. custom the outer veneers, while wooden studs formed the skeleton, firmly fastened via screws. Depicted in Figure 11 is the scaled building model, situated within the open-jet test section. Notably, most high-rise edifices examined in wind tunnels are markedly smaller in scale, typically ranging from 1:500 to 1:300 [78; 79]. Given the larger scale of this structure, scaling effects on wind load estimations were attenuated, resulting in a more realistic emulation of actual wind flow and associated pressures. The placement of the building, set at twice the height of the open jet from the exit of the blowers, necessitated a specialized configuration at its base to counteract shear and overturning moments. The specifics of the experimental arrangement, model configuration, pneumatic couplings, orientations of wind flow (0 and 90 degrees), and tube layout within the building model are depicted in Figure 11. Five pressure scanners were deployed at five discrete levels [57]. A statistical methodology was employed to obtain minimum and maximum pressures [80]. Although the conventional approach assumes a Gaussian distribution of response, it has been documented that stochastic responses may adhere to a non-Gaussian process. A recent examination has proposed using the Weibull distribution to model peak pressures [81]. Other investigations have concurred that the extreme value type I (Gumbel) distribution accurately represents peak pressures [82; 83; 84].