Effects of Incident Flows on Wind Loads and Their Combinations on a Low-Rise Building Immersed in a Long Upstream Fetch

Abstract

The primary purpose of the present study was to investigate the effect of incident flows (i.e., variations in terrain roughness) on wind loads and wind load combination effects on a target low-rise building. Three area densities-6, 11, and 25%-were considered, and three boundary-layer flows-a low-turbulent flow, and a grid-generated flow-were simulated. Results show that pressure coefficients for the isolated model differ significantly depending on the incident flows, which is a well-known fact, showing large absolute pressure coefficients for a flow with a larger power-law exponent (or high turbulence intensity). For the target model, which has other buildings in its immediate surroundings, the pressure coefficients seem to be less affected by the various incident flows, showing similar variation trends. The effects of boundary-layer flows on interference factor, zoning interference factor, and interference factor of combination factor, are small. Thus, it is concluded that terrain variations can be used to determine interference factors in other terrains, within the range in which most buildings are placed. However, those factors obtained from the grid-generated flow differ significantly from those from other incident flows. (C) 2014 American Society of Civil Engineers.