Patent ID: 8783721

Claim:
A metallic hollow columnar member with a polygonal cross-section having at least five vertices and sides extending between the vertices, wherein: the polygonal cross-section is divided by two vertices (A, B) with small inside angles into two perimeter segments with a perimeter comprising one or more sides, the at least one of the two perimeter segments containing at least four sides, the respective inside angles of at least three vertices (V(i) (i=1, 2, 3, . . . )) included in the perimeter segment which includes the at least four sides are equal to or less than 180 degrees, a distance (SS(i) (i=1, 2, 3, . . . )) between each of the at least three vertices (V(i) (i=1, 2, 3, . . . )) and a straight line (L) connecting the two vertices (A, B) is shorter than ½ of a distance between the two vertices (A, B), the inside angle of a vertex (C) with the smallest inside angle among the at least three vertices (V(i)) is larger than the inside angles of the two vertices (A, B), and vertices (VI) are present on the perimeter segment including the at least four sides, respectively between the vertex (C) with the smallest inside angle among the at least three vertices (V(i)) and one (A) of the two vertices (A, B), and between the vertex (C) with the smallest inside angle and the other (B) of the two vertices (A, B), said vertices (VI) having inside angles larger than the inside angle of the vertex (C) with the smallest inside angle.