Wind tunnel tests for mean wind loads on partially clad structures

Many structures, such as buildings under construction, industrial process structures, and manufacturing and storage facilities, are temporarily or permanently partially clad. Scant wind load data for these structures are available in the literature and wind codes. An investigation was undertaken at the L.S.U. Wind Tunnel Laboratory to study the aerodynamic behavior of these structures. Mean force coefficients for various cladding arrangements are reported for models of a 10-storey structure for two plan aspect ratios (1:1 and 3:1) in smooth, grid turbulent, and boundary layer flow. Three flow regimes were tested to validate results against published data and to investigate the possibility of reducing the number of key variables. Results for the fully clad and unclad cases compared well with available data for ground-mounted prisms and lattice frames, respectively. It was found that force coefficients for some of the cladding configurations significantly exceeded those for a fully clad structure of the same overall geometry. Additionally, the manner in which the force coefficients varied with wind direction was found to differ dramatically from the fully clad cases for some of the cladding arrangements. The conditioning of the approach flow was found to be less important for unclad models than for partially or fully clad configurations.