Effective Width of Chain Pillars

The effective width of a large rectangular chain pillar can be calculated by using either of the following formulae:

weff = (w1 x w2)0.5
OR
weff = 4A/C

Where:
w1 = width of one side of the chain pillar (metres)
w2 = width of the other side of the chain pillar (metres)
A = Area of the pillar (metres2)
C = Circumference of the pillar (metres)
h = height of the pillar (metres)

The following restrictions have been placed on the above formulae

w2 = 2w1 or w2, whichever is least,
If w1/h <= 5, w2 = w1,
If w1/h > 5 and w2 > 2w1, w2 = 2w1

Worked Example

Calculate the effective width of rectangular pillars of the following dimensions:

4 m high, 18 m wide and 36 m long.
3 m high, 18 m wide and 80 m long.

Solution

1.

w1/h <= 5
Therefore, Use weff = w1 = 18 m

2.

w1/h > 5
w2 > 2w1
Therefore, set w2 = 2w1 = 36 m

Option 1
weff = (w1 x w2)1/2
= (18 x 36)1/2
= 25.5 m

Option 2
weff = 4A/C
= 4 x (18 x 36)/(18 +18 + 36+ 36)
= 4 x (648/108)
= 24 m

Facebooktwittergoogle_plusredditpinterestlinkedinmailFacebooktwittergoogle_plusredditpinterestlinkedinmailby feather