Site Specific Wind and Ice

Wind Pressure Forces on Structures Engineers who design or analyze structures such as wireless communication and broadcast towers must account for the external forcing on the structure which results from wind pressure, and ice loading of the structure which affects the wind pressure. Wind speed and icing are both highly variable regionally and are also affected by local roughness of the surface, as well as topographic obstructions to flow which act to slow down or speed up the wind. The engineer needs information on what to expect for the maximum ice and wind load for the structure.

The drug was used during world war ii and found to be quite buy provigil online legit useful. Building Codes used for the analysis of towers, such as the TIA-222 and ASCE7 in the US and S37 in Canada, provide a mapping of the Basic extreme wind and ice, and a prescription for adjusting the basic values to account for the terrain and topographic corrections of the basic winds.

It is used in the united states to treat open-angle glaucoma, usually in people who have not responded to treatment with The codes recognize that the mapping introduces generalizations which may not provide the most appropriate values for wind load calculations in some regions (designated as special wind regions) and recommends Site Specific assessment in those cases.

ICE Approach to Site Specific Wind Extreme Assessment

The Site Specific assessment uses the most appropriate local hourly data and statistical procedures and the latest research literature to extract the wind extremes, coupled with the terrain and topographic corrections in deriving the wind and ice values for a site.

In carrying out thousands of such site specific assessments for ASCE7, TIA and S37 we at ICE Inc. have been able to identify some shortcomings in the codes which lead to failure to provide a complete picture of hazard conditions. These include the effect of tower location on elevated terrain in freezing rain events, the potential for rime icing on such structures, as well as rime icing on very tall towers on level terrain.

We have also used experimental and theoretical results to generalize the effect of changes in surface characteristics using a continuous measure of roughness to improve on the transition between differing terrain along the fetch to the structure, and to account for topographic effects which are not dealt with in the isolated hill or ridge case.