Experimental study of topographic effects on gust wind speed

This paper presents a follow-up study to our earlier work on comparing approaches to determine topographic effects in four major wind load codes. These codes are further evaluated and compared with earlier studies as well as new tests undertaken in the Texas Tech University boundary layer wind tunnel. Wind tunnel experiments with a model scale of 1:1000 were carried out to evaluate the wind speed-up effects of two main types of topography: escarpments and symmetrical ridges. Of particular interest were effects of ground surface roughness and the upwind slope of the two topographic features on wind speed-up and the space limits for speed-up applications around the crest of topography. Experimental results show that the surface roughness has significant speed-up effects for ridges rather than for escarpments. The results also indicate that wind load codes tend to be unconservative in specifying the minimum and maximum upwind slope as well as the spatial extent around the crest for application of speed-up factors.