Civil Engineering Reference
In-Depth Information
GEO limit state requirement satisfied since design bearing resistance (1738.8 kN)
>
design
effects of actions (1702.1 KN).
R
F
1738 8
1702 1
.
.
d
Over-design factor
,
Γ =
=
=
1 02
.
d
2.
Combination 2 (partial factor sets A2
+
M2
+
R1)
(ii) Design actions:
Again we use the total weight of the foundation and subtract the uplift force due to
water pressure under foundation.
Design value of self weight of concrete and soil (unfavourable, permanent action):
W
=
(
W
+
W
)×
γ
,
d
concrete
soil
G unfav
=
(
54 0
.
+
76 8
.
)
×
1 0
.
=
130 8
.
kN
Design value of the vertical structural (unfavourable) actions:
V
= ×
V
γ
+ ×
V
γ
=
(
800 1 0
×
.
)
+
(
350 1 3
×
.
)
=
1255
kN
d
G
G unfav
,
Q
Q unfav
,
Design value of water pressure under the base (unfavourable (negative) action - from
Single Source Principal):
U
= ×
U
γ
,
= − ×
(
1 5 2 0 2 0 9 81 1 0
.
.
×
.
×
.
)
×
.
=−
58 9
.
kN
d
G unfav
Design effect of actions (i.e. sum of vertical forces):
F W V
=
+ + =
U
130 8 1255 58 9
.
+
−
.
=
1326 9
.
kN
d
d
d
d
Overburden pressure: q
=
γ
soil
z
=
(20 - 9.81)
×
1.5
=
15.29 kPa
(iii)
Design material properties:
′
tan
φ
tan
.
28
1 25
°
=
=
Design angle of shearing resistance:
φ
′ =
tan
−
1
−
tan
1
23 0
.
°
d
γ
φ
′
=
γ
γ
γ
20
1
=
k
Design weight density of soil
:
γ
=
20 N m
k
/
3
d
(iv)
Design geometry:
No eccentric loading,
⇒
A'
=
B
×
L
=
2.0
×
2.0
=
4.0 m
2
No inclined loading,
⇒
i
c
=
1.0
Foundation base horizontal,
⇒
b
c
=
1.0
From EN 1997-1:
2004,
Annex D:
′
φ
=
′
N
q
=
e
π
⋅
tan
φ
tan
2
45
+
8 7
.
2
′
=
N
=
2
(
N
q
−
1
)
tan
φ
6 55
.
γ
d
s
q
= +
1
sin
φ
′ =
1 39
.
s
γ
=
0 7
.
(v)
Bearing resistance:
′
=
′
+
′
′
R/A
c N b s i
q N b s i
+
0 .
γ
B N b s i
c
c c c
q q q q
γ
γ γ γ
R
k
=
4 0
.
× +
[
0
(
15 29 8 7 1 0 1 39 1 0
.
× × ×
.
.
.
×
.
)
+
(
0 5
.
×
(
20 9 81
−
.
)
×
2 0 6 55
.
×
.
× × ×
1 0 0 7 1 0
.
.
.
)]
=
926 5
.
kN
