Civil Insight: A Technical Magazine Volume 3 | Page 60

Gautam A. et al.
Civil Insight (2019) 57-63
ߩ ൌ 
‫ܩ‬ሺܽ‫݄ݐ݌݈݁݀݀݅݉݁݅݌ݐ‬ሻ
ሺͶሻ
‫ܩ‬ሺܽ‫݌݅ݐ݈݁݅݌ݐ‬ሻ
Further, the stiffness of the soil spring for the pile tip was approximated by using the solution of Boussinesq
(1885) for a rigid footing resting on an elastic half space. The stiffness of the pile tip is expressed as
‫ܭ‬ ௕௔௦௘ ൌ 
Ͷ‫ݎܩ‬ ଴
ሺͷሻ
ሺͳ െ ߥሻ
The values of lateral spring stiffness of soil were calculated using Vesic (1961), as expressed in Eqn (6).
ሺ݇ ௦ ሻ ௩௘௦௜௖ ൌ
ͲǤ͸ͷ‫ܧ‬ ௦ భమ ‫ܧ‬ ௦ ‫ܤ‬ ସ
ሺ͸ሻ
ඨ
ͳ െ ߥ ଶ
‫ܧ‬ ௣ ‫ܫ‬ ௣
After modeling the foundation in SAP2000 (SAP2000, 2015), analysis was run and the results were
obtained at the intersection of the base of the pile cap and the piles.
3) Observations and Results
3.1) Load Distribution on piles using the Classical Method
The load calculated at the base of the pile cap is shown in Table 2.
Table 2. Load at the base of the pile cap
Axial Load (kN) Moment Longitudinal or ML (kNm) Moment Transverse or MT (kNm)
18720 8351 21244
The distribution of loads using the Classical Method was evaluated using Eqn (1), which is shown in Table
3.
Table 3. Distribution of load axial on piles using the Classical Method
Pile X (m) Y (m) X 2 (m 2 ) Y 2 (m 2 ) Axial (kN)
1 -4.50 -4.50 20.25 20.25 2 -1.50 -4.50 2.25 3 1.50 -4.50 4
5
6
7
8 4.50
-4.50
-1.50
1.50
4.50 9 1170 Due to ML
(kN)
-208.8 Due to MT
(kN)
-531.1 Total
(kN)
430
20.25 1170 -208.8 -177.0 784
2.25 20.25 1170 -208.8 177.0 1138
-4.50
-1.50
-1.50
-1.50
-1.50 20.25
20.25
2.25
2.25
20.25 20.25
2.25
2.25
2.25
2.25 1170
1170
1170
1170
1170 -208.8
-69.6
-69.6
-69.6
-69.6 531.1
-531.1
-177.0
177.0
531.1 1492
569
923
1277
1631
-4.50 1.50 20.25 2.25 1170 69.6 -531.1 708
10 -1.50 1.50 2.25 2.25 1170 69.6 -177.0 1062
11 1.50 1.50 2.25 2.25 1170 69.6 177.0 1417
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