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. Loading Data

Loading : a. Permanent Load b. Temporary Load

P = Axial Load

( w/o foundation weight )= . on = . on

Vx = Shear ( x - direction )= 0.56 ton Vx = 2.95 ton

z = ear z - r ec on= . on z = . on

x = omen x - r ec on= 0.72 ton. m Mx = 0.00 ton.m

Mz = Moment ( z - direction )= . on.m z = . on.m

Note : Leter inside bracketmeans Forces which have direction perpendicular

to this plane.

2. Assumed Dimension

Foundation Size Data :H = 160 cm

Df = 160 cm= cm= cm

hf = 40 cmd = 32.5 cm

= cm= cm

Punching Shear Line :

= + = . cmb2 = h + d = 82.5 cmc1 = b/2 + d = 57.5 cmc2 = h/2 + d = 57.5 cm

3. Check of Soil Reaction "fe"

Design Loads :

a) Vertical Loads (P)

Perm. : P tot = P + Wf = 131210.0 kg

Temp. : P tot = P + Wf = 26920.0 kg

Where,Wf Wp + Wb + Ws = 3300 Kg

Wp = Pedestal weight = 720 Kg

Wb = Footing weight = 960 Kg

Ws = Soil weight on Footing = 1620 Kg

b) Moment due to Horizontal Force (M)

Permanent : Temporary :

Mx1 = Vx . H Mx1 = Vx . H

= 896 kg m = 4720 kg m

Mz1 = Vz . H Mz1 = Vz . H

= 32 kg m = 4125 kg m

c) Eccentricity (e)

- Perm. : Mx.tot = Mx1 + Mx = 1616 kg m ex = cm

Mz.tot = Mz1 + Mz = 63 kg m ez = cm

- Temp. : Mx.tot = Mx1 + Mx = 4720 kg m ex = cmMz.tot = Mz1 + Mz = 4125 kg m ez = cm

d) Compute "fe" : P tot

B . L

Take " " depend on " e " condition below :

= 1 + factor x + factor z

Where : ex(ez) < B(L)/6, factor x (z) = 6 ex(ez)/ B (L)

ex(ez) > B(L)/6, factor x (z) = 2/ [3{0.5-ex(ez)/ B (L)}]

for this case :

- Perm. : ex < B/6 Factor x =

ez < L/6 Factor z =

Xn = Neutral Axis

- Temp. : ex > B/6 Factor x =

ez < L/6 Factor z =

SPREAD FOUNDATION

1.2316

0.0480

17.533415.3224

0.07

0.00

0

0.92

P

Mx

Vx

H

H Df

hfd

b2

c2

c1

b1

L

B

h

b

Xn > B

Xn < B

P tot

ex

x

z

afe =

B (L)

Df

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e) Allowable soil stress "Fe" :

- Permanent - Temporary

Fe = 16.00 kg/cm2 Fe = 20.80 kg/cm2

f) Soil stress "fe" :

- Permanent - Temporary

P tot = 14.13 kg/cm2

P tot = 5.17 kg/cm2

B * L B * L

< Fe OK ! < Fe OK !

= 1.077 = 1.919

4. Check of Stability

Permanent : Temporary :Overturn ing Moment ( OM ) : Mx to 1616 kg m Mx tot = 4720 kg m

Mz tot = 63 kg m Mz tot = 4125 kg m

es s an omen : o . g m o . = g mo . = g m o . = g m

Permanent Load : RM / OM = Ptot . B 40.6 > 2.0

2 . Mx tot

Ptot . L 1041.3 > 2.0

2 . Mz tot

Temporary Load : RM / OM = Ptot . B 2.9 > 1.5

2 . Mx tot

Ptot . L 3.3 > 1.5

2 . Mz tot

5. Footing Design

5.1 Design Soil Reaction "qus"

fe max = 14.128 kg/cm2

qus = 1.6 * ( fe max - Wf ) 22.077 kg/cm2

; Note : 1.6 is used an average load factor,

B . L because the proportion of dead and live load are not known.

5.2 Required Re-bar due to Bending Moment

a. Design Moment :

Mux = qus . L . ( B - b )2/8 = 6899.2 kg m

Muz = qus . B . ( L - h )2/8 = 6899.2 kg m

b. Steel Ratio, r :

fy = 4000 kg/cm

fc' = 122.5 kg/cm2

m = fy 38.4 ; = 0.9

0.85 fc'

- About x - dirrection :

Rn = Mux 7.3 kg/ cm2

L d2

r req = 1 1 - 1 - 2 m Rn 0.0019 < r min

m fy

r min = 1.4 0.0035

fy r min = 0.0025

r r = 1.33 * rreq 0.0025

r o = 0.0025

As = r o * L * d 8.1 cm2

D = 16 mm ; Ab = 2.01 cm2

n = A s / Ab 5

Spacing, s = 210 mm ; whichever is smaller.

Spacing Limit : S max = 2d = 650 mm Spacing s = 210 mm

take : D 16 - 210

- About z - dirrection :

Rn = Muz 7.3 kg/ cm2

B d2

r req = 1 1 - 1 - 2 m Rn 0.0019 < r min

m fy

r min = 1.4 0.0035

fy r min = 0.0025

r r = 1.33 * rreq 0.0025

r o = 0.0025

As = r o * B * d 8.1 cm2

D = 16 mm ; Ab = 2.01 cm2

n = A s / Ab 5

spacing, s = 210 mm Whichever is smaller.

Spacing Limit : S max = 2 d = 650 mm spacing s = 200 mm

take : D 16 - 200

5.3 Check of Shear Stress

Vux = qus * ( B/2 - c1) / d = -5.09 kg/cm2