EFFECTS ON SURFACE-ROUGHNESS FOR WIND PRESSURE ON GLASS AND CLADDING OF BUILDINGS

High rise multiple dwelling houses with balconies have been frequently constructed in recent years because of the concentration of populatio n in a big city. The wall surface of buildings with balconies and mull ions, becomes extremely rough. To the present, wind loading on glass a nd cladding have been mainly derived from tests on buildings with smoo th surfaces. However, effects of reduction of wind pressures are consi derable for walls with surface roughnesses such as balconies. The pape r describes the results of an experimental study carried out in a Gott ingen-type wind tunnel under uniform flow and boundary layer flow over urban terrain. The basic model of study represented square buildings 75 m high and 25 m wide in a scale of 1/300. The surface roughness att ached on all building walls was: uniform roughness of maximum size equ al to 0.21 m in full scale, and three kinds of balconies of 0.63, 1.25 and 2.5 m wide without mullions, and 0.63 m wide balconies with mulli ons. The experimental data indicate that wind pressures were remarkabl y affected by the surface roughness, particularly near the leading edg e of the side wall on which local severe peak pressures decrease with increasing roughness, and that the increment of roughness restrains th e development of conical vortices formed at the lower and higher zone of buildings from discussion of power spectra and root-coherence for f luctuating wind pressures. The paper quantifies the effects and makes appropriate recommendations. (C) 1998 Elsevier Science Ltd. All rights reserved.