Net Effective Area:

In tension members, the calculation of 'net effective area' of cross section [Gross Area (Ag) - Area of deductions (Ad)] is important. Deductions may be caused mainly due to following two reasons:

Holes

Made within the member for rivets, bolts, etc.

Unconnected (or Outstanding) Legs

Since distribution of stresses in connected and unconnected legs are different, (the former carrying higher stresses).

An provision of the Indian Standard Code IS 800: 1984 in this respect may be summarized as follows:

Deduction for Holes

The deductions in area for holes should be made as per guidelines given and shall be the sectional area of the maximum number of holes in any cross section at right angles to the direction of stress taking into account the zig-zag section if the holes are staggered. Refer Figure 6.

A number of holes to be given in built up tension members is given in Table.

Table: Built-up Tension Members