Abstract
It is generally to use a square as a section of structure of towers. However, there are towers as a section of equilateral triangle, rectangle, hexagonal triangle and others, which are not square in construction of tower by the purpose of using. It is not so many wind tunnel experimental datas about structure of towers and are not obvious relationship between drag-coefficient and projection ratio in to case of a design. We investigated the relationship between drag-coefficient and projection ratio on towers of special section and variation of drag-coefficient in the case of changing wind direction. We investigated as follows as obvious facts : In the case of a special sections (equilateral triangle, rectangle, hexagonal triangle), a relationship between wind direction and drag-coefficient fitted as the result of a square section by calculating drag-coefficient with projection area. In the case of towers of a special section, a relationship between projection ratio and drag-coefficient was obviously investigated as same as a square section which is divided into three groups.
