mathcad - concrete footing with pedestal
TRANSCRIPT
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tftg1 1.0 mtftg2 0.5 mdsoil 1.0 m (depth of soil)
Lftg 2.2 m (latudinal dimension)
Wftg 2.2 m (longitudinal dimension)
aw 0.63m (pedestal short dimension)
aL 0.63m (pedestal long dimension)
30 (soil angle of friction)
Mload 85.15kN m conc 24kN
m3
Hload 0.46 kNVload1 28.27 kN soil 19
kN
m3
Vload2 25.32kN
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OVERTURNING MOMENT, MO
MO Mload Hload tftg1 tftg2 MO 85.84 kN m
RESISTING MOMENT, MR
Wtftg conc Lftg Wftg tftg2 aw aL tftg1 Wtftg 67.606 kN
MR Vload1 Wtftg soil Wftg Lftg aw aL dsoil Wftg2MR 136.13 kN m
OVERTUNING MOMENT FACTOR OF SAFETY, FOSOT
FOSOTMRMO
1.586 > 1.5; OK
SLIDING FORCE, HSL
soil 31.5 (angle of internal friction)
soil tan soil 0.613 (soil coefficient)HSL Hload 0.46 kN (craine sliding force)
SLIDING RESISING FORCE, HRF
HRF Vload1 Wtftg soil (sliding resisting force)HRF 24.105 kN
SLIDING FACTOR OF SAFETY, FOSSL
FOSSLHRFHSL
52.402 ; OK
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SOIL BEARING
soil1Vload1 Wtftg soil Wftg Lftg aw aL dsoil
Lftg WftgMO
Wftg2
Lftg Wftg3
12
soil2Vload1 Wtftg soil Wftg Lftg aw aL dsoil
Lftg WftgMO
Wftg2
Lftg Wftg3
12
soil1 73.939 kPa
soil2 22.801 kPa ;Negative soil pressure is rejected. Use another approach
ECCENTRICITY OF VERTICAL FORCE
eOMO
Vload1 Wtftg soil Wftg Lftg aw aL dsoileO 0.694 m
rWftg2
eO
r 0.406 m
SOIL BEARING
f 2( )Vload1 Wtftg soil Wftg Lftg aw aL dsoil
3r Lftg
f 92.284 kPa < 200 KPa; OK
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PUNCHING
dbar 16 mmcon 0.65d tftg2 75 mm dbar2 0.417 mfc 23 MPa
Bo aw 2 aL 2d28
min aL aw max aL aw
1Bo 4.188 m 1s 40Vult1 39.58 kN Vult2 35.45 kN
Shear 1.2 conc aw aL tftg1 Vult2Shear 46.881 kNfcmax min fc 70 MPa( ) 23 MPa ACI 318M-08 Sec.11.1.2
Vc1 0.17 12
fcMPa
MPa Bo d ACI 318M-08 Sec.11.11.2.1 Eq. 11-31
Vc1 4271.465 kN
Vc2 0.083s dBo
2
fcMPa
MPa Bo d ACI 318M-08 Sec.11.11.2.1 Eq. 11-32
Vc2 4159.008 kN
Vc3 0.33 fc
MPa MPa Bo d ACI 318M-08 Sec.11.11.2.1 Eq. 11-33
Vc3 2763.889 kNVc con min Vc1 Vc2 Vc3 1796.528 kN > Shear 46.881 kN ;OKONEWAY SHEAR
Shear 46.881 kN
Vsc con 0.17 fc
MPa MPa min Lftg Wftg d
Vsc 486.166 kN > Shear 46.881 kN ;OK
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BENDING REINFORCEMENT
xwWftg aw
2
xw 0.785 m
SOIL STRESS AT PEDESTAL EDGE
fxf xw3 r
fx 59.423 kPa
FOOTING MOMENT
Mftg 1.6 Lftg fxxw
2
2 f fx xw
2
3
Mftg 88.207 kN m