2　Terms and Symbols

2.1　Terms

2.1.1　Height of tower

Vertical distance from the bottom of tower base plate to the top lightning rod.

2.1.2　Tower spacing

Distance between adjacent center lines of trilateral and quadrangular towers.

2.1.3　Slenderness ratio

A ratio between the calculated member length and the radius of gyration of member section.

2.1.4　Major member

A pylon of tower and mast structure，i.e.main stressed member corresponding to the chord of space truss.

2.1.5　Web member

A support member connecting each major member of the tower，including cross member and diagonal member.

2.1.6　Horizontal Cross member

A member used to connect cross member.

2.1.7　Secondary member

A member used to reduce the calculated length of stressed member.

2.1.8　Steel tower

A free-standing high-rising steel framework.

2.1.9　Steel pole

A free-standing high-rising steel framework consisting of a single large-diameter steel tube and platform（s）.

2.1.10　Guyed steel mast

A high-rising steel structure consisting of columns and guys.