Civil Engineering Reference
In-Depth Information
Load combination 3:
6e
b
⋅
qif
e
b
1
6
⋅
3
3
1
+
≤
=4.3 ksf
⋅
ave3
q:
=
4
31
2e
b
qif
e
b
1
6
e
b
1
2
max3
3
3
⋅
≥
∧≤
ave3
3
⋅
−
The maximum soil pressure shall not exceed the admissible soil pressure.
Note that it is typically acceptable to increase the allowable soil pressure when
the maximum pressure is investigated. Here, an increase of 20% is deemed
appropriate. The ratio between the eccentricity and the side of the footing,
e/b, is also normally limited to a maximum of 0.25. Furthermore, under seis-
mic or wind loading the allowable soil pressure can be increased by 33%.
Load combination 1:
“OK” if q
≤⋅ σ
1.2
max1
adm
CheckSoilPressure1:
=
“Not good”otherwise
CheckSoilPressure1 = “OK”
Load combination 2:
“OK” if q
≤⋅ σ
1.2
max 2
adm
CheckSoilPressure2:
=
“Not good”otherwise
CheckSoilPressure2 = “OK”
Load combination 3:
“OK” if q
≤⋅
1.2 1.33
⋅σ
max3
adm
CheckSoilPressure3:
=
“Not good”otherwise
CheckSoilPressure3 = “OK”
10.5.3 Ultimate pressure under the footing
To proportion the footing for strength, factored loads are considered.
Load combination 1:
P
u1
:= 1.4P
D
= 266⋅kip
M
u1
:= 1.4⋅M
D
= 44.8⋅kip⋅ft
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