ANNULAR PILE CAP DESIGN OF Sarenga PWSS - 6
ANNULAR PILE CAP DESIGN OF Sarenga PWSS - 6
ANNULAR PILE CAP DESIGN OF Sarenga PWSS - 6
65
3 Inner Pile Line 2.6 2.6/6.4 0.41
4 Column Line 4.25 4.25/6.75 0.65
Calculation of Tangential Moment for f = 0.665 (Ref: Design of Tall Chimnyes by S.M. Monohar,
Chart-6.3)
Sl. Load Location Moment
Ring Load Mr x 102/a (at f = 0.63)
No. (β) Factor
1 Q1 0.93 -5 (-5) x (-328.55) = + 1642.75
2 Q2 0.65 -23.5 (-23.5) x (-298.95) = + 7025.33
3 Q3 0.41 -21 (-21) x (-278.90) = + 5856.90
4 R1 0.65 -23.5 (-23.5) x (925.56) = -21750.66
Total Moment (Kn) = -7225.68
Calculation of Radial Moment f = 0.33 (Ref: Design of Tall Chimnyes by S.M. Monohar, Chart-
6.2)
Sl. Load Location Moment
Ring Load Mr x 102/a (at f = 0.63)
No. (β) Factor
1 Q1 0.93 -5 (-5) x (-328.55) = + 1642.75
2 Q2 0.65 -23.5 (-23.5) x (-298.95) = + 7025.33
3 Q3 0.41 -28 (-28) x (-278.90) = + 7809.2
4 R1 0.65 -23.5 (-23.5) x (925.56) = -21750.66
Total Moment (Kn) = -5273.38
Now,
Radial moment at outer edge (Mtβ1) = (-7225.68x 6.4) / 100 = (-) 462.45 KN-m/m. and
Radial moment at inner edge (Mtα) = (- 5273.38 x 6.4) / 100 = (-) 337.52 KN-m/m.
As in reality, this inner edge is a free edge. For an annular raft apply equal and opposite moment
in the inner surface. The sum of the two effects will give the final value.
Now, applying an equal and opposite moment, Mα at f = α, the radial moment at f = β is:
𝛼 2 (1 + 𝑓 2 )
𝑀𝑡𝛽2 = 𝑀𝑡𝛼 𝑥 2 𝑥
𝑓 (1 − 𝛼 2 )
So, Radial Moment, Mtβ2 = (-337.52) x (0.1089/0.442) x ( 1.442 / 0.891) = -134.61Kn-m/m