Many shapes and size are used. The steel structure can have the following basic shapes:
Square, rectangle, ELL, channel and "I" section. Combinations of these sections are used. The cross section of any structural member has the following properties: area of cross Section, circumference, moment of inertia about X - axis, moment of inertia about Y- axis, Product of inertia, section modulus about X - axis, section modulus about Y - axis, Warping constant, center of gravity, distance to extreme fibers and paint area.