DESIGN OF ISOLATED SQUARE FOOTING

INPUT DATA:
Concrete Strength, f'c =

27.6

MPa

teel Yield Strength, fy =

414

MPa

Column size, b
h
Soil Pressure, Ps

Reduction factor,

PDL
PLL

= 0.90 (for flexure)

= 0.85 (for shear)
= 600 mm
= 300 mm
= 20.877 ksf
= 1000 kPa

Axial Deadload, PDL = 772.00 kN

Axial Liveload, PLL = 376.00 kN
Ultimate Axial Load, PU = 1720.0 kN

t
L

Weight of Footing: (10% of column load)

WF =
### kN
Total Load =
Required Area
L
TRY 1.0
Area

### kN

=
1.15
= 1.071
x 1.0
=
1.00

m2
m
m
m2

Net Ultimate Upward

PsNU = 1720.0 kPa
Soil Pressure,
Allowable Ultimate
PsALLOW =
Soil Pressure,

### kPa

Compute "d" by Punching Shear:

Allow. Punching Shear, V ( 1 + 2/c ) f'c/6
long side of column
c =
short side of column
= 2
Vc =

1.75

MPa

OR, Vc = f'c/3
= 1.75 MPa 0 0.00 MPa
0 =
0.00 MPa

309153893.xls

03/11/2016

Actual Punching Shea

Vn =

### =

0.00 d2

Vu
bod

Vu =

1720.00 [( 1000 )2 -( 600 + d)2] 1000

0.85 ( 600 + d ) 4d (1000)2

+ 1200.00 d

d + 1200 d
2

640000
- 640000 = 0

=0

200

600

By Quadratic Equation:
d = 400.00 mm
d =
400
mm

TRY

CHECK FOR BEAM SHEAR:

Actual Beam Shear,
n =

1000
Vu
bd

Vu = -688 kN
n = -2.02 MPa

-400 400

Allow. Beam Shear, c = f'c/6

= 0.876 MPa > -2.02

MPa safe for BEAM SHEAR

STEEL REINFORCEMENTS:
By Bending:
Mu =
34.40 kN-m
reqd =
0.0262
min
As
TRY 20
As1bar
no. of bars
USE 33

=
0.0034
=
### mm2
mm bar
= 314.160 mm2
= 33.32
- 20 mm bar

Development Length:
Required Ld =

0.02 Ab fy
f'c

Ab = ### mm2

= ### mm
Minimum Ld = 0.06 db fy
or 300 mm

= 496.8 mm2

Ld furnished = 130.0 mm

309153893.xls

03/11/2016

Check for Bearing Strength:

Bearing strength = 0.85 f'c A1 A2/A1
A1 =
### mm2
A2 =
### mm2
A2/A1 = 2.36
> 2.0
Use A2/A1 =
Bearing strength =
=
Check Weight of Footing:
Total depth =
Actual weight of footing =
Total weight =
Area required =

309153893.xls

2.0
5911920
5912 kN

N
> 1148 kN

SAFE

500 mm
11.77 kN
### kN
1.160 mm2

> 1.15 mm2 INCREASE A

03/11/2016

ROBINSON'S LIPA
DESIGN OF SLOPED SQUARE FOOTING
INPUT DATA:

F-5

Concrete Strength,
Steel Yield Strength

f'c =
fy =
=

Reduction factor,

Soil Pressure,

b
h
Ps

Axial Deadload,
Axial Liveload,

PDL
PLL

Column size,

41.4 MPa
414 MPa
0.90 (for flexure)

=
0.85 (for shear)
=
1000 mm
=
1000 mm
=
3.5 ksf
= 167.65 kPa
=
7609 kN
=
### kN

Axial Earthquake,
Peq =
0 kN
P
Ultimate Axial Load,
### kN
U =
Weight of Footing: (8% of column load)
WF = 806.64 kN
Total Load =

### kN

d/2= 550

800
d'

300

3250
###
d' =

984 mm > d/2

SAFE

Required Area = 64.95 m2

L = 8.059 m
TRY### x 8.60
m
Area =

73.96 m2

Net Ultimate Upward

PsNU = 220.86 kPa
Soil Pressure,
Allowable Ultimate
PsALLOW = 271.59 kPa
Soil Pressure,
Compute "d" by Punching Shear:
Allow. Punching She Vc = ( 1 + 2/c ) f'c/6
long side of column
c =short side of column
= 1
Vc =
OR,

3.22 MPa

Vc = f'c/3
= 2.14 MPa
USE Vc =
2.14 MPa

309153893.xls

<

3.22 MPa

03/11/2016

309153893.xls

03/11/2016

Actual Punching She

Vn =

2.14 =

33.02 d2
d

Vu
bod
(
+ d)2] 1000
220.855 [( ### )2 - ###
0.85 ( ### + d ) 4d (1000)2

+ 35017.94 d

7E+007 = 0

2E+006 = 0

1029 d

3800

1000

By Quadratic Equation:
d =
d =

TRY

1037.61 mm
mm
1100
8600

Check for Beam Shear:

Actual Beam Shear,

n =
Vu =
n =

Allow. Beam Shear,

Vu
bd
5128.26 kN
### ###

0.638 MPa

c = f'c/6
=
1.072 MPa

> ### MPa

SAFE

STEEL REINFORCEMENTS:
By Bending:
Mu = 13713.35 kN-m
reqd =
0.0023
min =
0.0034
As =
TRY
###
As1bar =
no. of bars =
USE 52 s =
Development Length:
Required Ld =

31990.34 mm2
mm bar
615.7536 mm2
51.95
28 mm bar
166 mm
0.02 Ab fy
f'c

Ab = 615.7536 mm2
Required Ld =
792 mm
Minimum Ld = 0.06 db fy or 300mm
=
695.52 mm

309153893.xls

03/11/2016

Ld furnished =

309153893.xls

3730 mm

03/11/2016

Check for Bearing Strength:

Bearing strength = 0.85 f'c A1 A2/A1
A1 =
### mm2
A2 =
### mm2
A2/A1 =
8.6 > 2
Use A2/A1 =
2
Bearing strength =
=

### N
49266 kN

>

10083 kN SAFE

Area required = 72.732 mm2 <

73.96 mm2SAFE

Check Weight of Footing:

Total depth =
Actual weight of footing =
Total weight =

309153893.xls

1212 mm
### kN
### kN

03/11/2016

309153893.xls

03/11/2016

LU residence
SQUARE FOOTING
F-1
INPUT DATA:
Concrete Strength,
Steel Yield Strength,
Reduction factor,
Column size,
Allowable Soil Pressure,

f'c
fy
f
f
b
h
Ps

Fixed Footing Width, B

Axial Deadload, PDL
Axial Liveload, PLL
Ultimate Axial Load, PU
Unit Weight of Soil, wSOIL
Main Reinforcement,
FOOTING AREA:
PTOTAL =

107

= 27.6 MPa
= 414 MPa
= 0.90 (for flexure)
= 0.85 (for shear)
= 200 mm
= 400 mm
= 3.00 ksf
= 143.6 kPa
= 0.90 m
= 87.64 kN
= 19.78 kN
= 156.3 kN
= 16.00 kN/m3
= 12 mm.

kN

h = 1.00

t = 0.30 m (assumed)
Allowable qNET = Ps - (wsoil x h) - (wconcrete x t)
= 120 kPa
AREA = P/qNET =
0.9 m2
A = length x width
L = B = 0.94 m
USE 1.00 X 1.00
AACTUAL =
1.0 m2

FOOTING

THICKNESS:
Average qNET = Pu/A
= 156.3 kPa
TRY t =

300

mm

dS

dL

CHECK FOR PUNCHING SHEAR:

dAVE = t - cc - f
=
213 mm

PULTIMATE =

156

kN

d/2

d/2
156.3 kPa
c+d

c+d

c + d = column width + dAVE

= 413 mm
bo = 4*(c + d)
= 1652 mm

To be safe, Vup Vcp

Vup = Pu - [Average qNET * (c + d)]
=
130 kN
f f'c
bo d
3
= 492
kN

Vcp =

Vup < Vcp, safe for PUNCHING SHEAR

CHECK FOR BEAM SHEAR:
d = dAVE + f/2
= 219.0 mm
To be safe, Vu Vc

1.00 m.

Vu =

28.294 kN

f f'c
bd
6
= 162.99202 kN

1.00
m.

Vc =

Vu < Vc, safe for BEAM SHEAR

x

d
0.40

0.20

0.40

REINFORCEMENT:

dAVE = 219 mm

PULTIMATE = 156 kN
Mu =

Rn =

156
0.40

rmin = 0.0034

0.20
1.00

kPa
0.40

r=

WuL2
= 12.51
2
Mu
fbd2

= 0.2897

0.85f'c
fy

[ 1-

kN-m

MPa

1-

2Rn
0.85f'c

As = 741 mm2
As1bar = 113.1 mm2
n = 6.55
PROVIDE 7 - 12 mm bars

] = 0.0007

DESIGN OF SQUARE FOOTING

INPUT DATA:
Concrete Strength, f'c = 3000
Steel Yield Strength, fy = 60000
Reduction Factor, = 0.85
Column Size, b = 47.24
h = 47.24
Allowable Soil Pressure, Ps = 4.20
Service Deadload, PDL = 7.86

P
psi
psi
in
in
ksf

Hs

kips

Service Vertical Load, PVL = 41.37 kips

L
Assume average weight of soil
and concrete above footing ba =
Height of Soil, Hs =

150
8.20

Tributary area

pcf
ft

BASE AREA:(Using Service Loads w/ Net Permissible Soil Pressure)

Total Weight of Soil = 1.23 ksf
Net Permissible Soil Pressure = 2.97 ksf
Req'd. Base Area, Af = 16.576 ft2
L = B = 4.0713 ft
USE 5.9 x 5.9
Af = 34.8

ft. SQUARE FOOTING

ft2

To proportion the footing for strength (depth and req'd. rebar),

factored loads are used.
Pu = 60.86 kips
Soil Reaction, qs =

1.75

ksf

DEPTH OF FOOTING:
5.90 ft
11.12 Determine depth of footing
based on shear strength w/o
shear reinforcement. Dept
required for shear usually
controls the footing thickness.

47.24 "+d
d/2

5.90 ft

47 "+d
d

Both wide-beam action an

two-way action for strength
computation need to be in
tigated to determine the
controlling shear criteria fo

bo for two-way action

bw for beam action

depth.

Assume t = 23.62 in
def = 18.62 in
= 1.55 ft
1. Wide-beam action:
Vu = qs x tributary area
bw = 19.68 ft
=
Tributary area =
Vu =
Vn =
=

### in
-11.22 ft2
-19.61 kips
(2f'cbwd)
409.4 kips > Vu OK

2. Two-way action:
Vu = qs x tributary area
(b + d)(h + d)
Tributary area = W x L 144

h of footing
strength w/o

= 4.69 ft2
Vu =

8.20 kips
4
2+ = 6
c

Vc
f'cbod

= minimum of

sd
bo
4

+2 = 5
=4

bo = 2(b+d) + 2(h+d)
= 263.4 in
c = b/d
=1

ting thickness.
bo/d = ###

for strength
s = 40
Vc = ###

> 8.2

kips OK

USE : 4

FOOTING REINFORCEMENT:
4 ft
47 in

-1.901

Critical section for moment

(long projection)

Clear cover (bott

24 in

d= 18.62

in.

qs = 1.75 ksf

1. Critical section for moment is at face of column

Pu = 60.86 kips
qs = 1.75 ksf
Mu = 3.22 ft-kips
2. As required
Required Rn =

Mu
= 0.52 psi
bd2
0.85f'c
fy

(1-

= 0.000009
(gross area) = d/h x 0.0025= 0.000007
min = 0.0034
Required As = bd

= ### in2

USING # 8 bars:
As = 0.785 in2
PROVIDE :###-# 8

1 - 2Rn/0.85f'

bars each way

3. Check development reinforcement

Critical section for development is the same
as that for moment (at face of column).

n for moment

3fy
ld
=
40f'c
((c+Ktr)/db)
db

Clear cover (bottom and side)= 3.0 in

nter-to-center bar spacing=

13 in

c = 3.5 in
c = 6.4 in
USE c = 3.5 in

c + Ktr
db

Ktr = 0

(no transverse reinforcement)

= 3.5

2.5 USE ###

>

= 1.0 (less than 12 in. of concrete below bars)

= 1.0 (uncoated reinforcement)
= 1.0 < 1.7
= 1.0 (larger than #7 bars)

= 1.0 (normal weight concrete)

ld
= 33
db
ld = 33

FOOTING ID:
INPUT DATA:
Concrete Strength, f'c
Steel Yield Strength, fy
lowable Soil Pressure, qa
Column width, b
Column depth, h
Main bar diameter,

=
=
=
=
=
=

27.6
414
287.4
0.300
0.300
16

MPa
MPa
kPa
m
m
mm

1.20
Y

Allowable Soil Pressu

0.90
1.20

b
COLUMN LOADS:
Axial Deadload, PDL =
Axial Liveload, PLL =

278

kN

85

kN

Total Axial Load, PT = ### kN

Footing Area, A =

PT
qa

= 1.389 m2

B=H
Try B = H
t
def = t-cc-

= 1.179 m
= 1.20 m
= 400 mm
= 317 mm

REINFORCEMENT:
Ultimate Load, Pu = 533.7 kN
qu =

Mu =

Pu
A

= 384.1 kPa

WuL2
= ### kN-m
2

0.45
CHECK FOR BEAM SHEAR:
Vu = 268.7 kN
Vc =

f'c
bd= 283
6

kN

Vc > Vu, safe for BEAM SHEAR

CHECK FOR PUNCHING SHEAR:
Vu = ### kN
Vc =

f'c
bod= 724
3

kN

bo = 1.534 m
Vc > Vu, safe for PUNCHING SHEAR

Rn =

Mu
= 1.720 MPa
fbd2

1200

act = 0.0043
rmin = 1.4/fy = 0.0034
As = 1643 mm2
USE :

8 - 16 mm bar

1200

8 -16mm bar
BOTHWAYS

FOOTING ID: F-2

INPUT DATA:
Concrete Strength, f'c
Steel Yield Strength, fy
Allowable Soil Pressure, qa
Column width, b
Column depth, h
Main bar diameter,

=
=
=
=
=
=

27.6
414
287.4
0.600
0.600
16

MPa
MPa
kPa
m
m
mm

COLUMN LOADS:
Axial Deadload, PDL =

650

kN

Axial Liveload, PLL =

517

kN

2.10
Y

Allowable Soil Pressur

1.50
b

2.10
h

Total Axial Load, PT = 1284 kN

Footing Area, A =

PT
qa

B=H
Try B = H
t
def = t-cc-f

= 4.467 m2
= 2.113 m
= 2.10 m
= 500 mm
= 417 mm

REINFORCEMENT:
Ultimate Load, Pu = ### kN
qu =

Mu =

Pu
A

= ### kPa

WuL2
= 946.2 kN-m
2

1.50
CHECK FOR BEAM SHEAR:
Vu = 910.9 kN
Vc =

f'c
bd=652
6

kN

Vc < Vu, increase size

CHECK FOR PUNCHING SHEAR:
Vu = ### kN
Vc =

f'c
bod=1635 kN
3

bo = 2.634 m

NG SHEAR

Vc > Vu, safe for PUNCHING SHEAR

Rn =

Mu
= 2.879 MPa
fbd2

act =
rmin = 1.4/fy =
As =
n=
USE :
32 -

0.0074
0.0034
6518 mm2
32.42
16mm bar

2100

2100

32 - 16mm bar
BOTHWAYS

FOOTING ID:
F-3
INPUT DATA:
Concrete Strength, f'c
Steel Yield Strength, fy
Allowable Soil Pressure, qa
Column width, b
Column depth, h
Main bar diameter,

= 21 MPa
= 414 MPa
= 114.9 kPa
= 0.500 m
= 0.300 m
= 16 mm

2.00
Y

1.70
2.00

b
COLUMN LOADS:
Axial Deadload, PDL = ### kN
Axial Liveload, PLL = 73.69 kN

Total Axial Load, PT = ### kN

Footing Area, A =

PT
qa

B=H
Try B = H
t
def = t-cc-

= 4.144 m2
= 2.036 m
= 2.00 m
= 500 mm
= 417 mm

REINFORCEMENT:
Ultimate Load, Pu = 628.1 kN
qu =

Mu =

Pu
A

= 151.6 kPa

WuL2
= ### kN-m
2

0.75
CHECK FOR BEAM SHEAR:
Vu = 388.9 kN
Vc =

f'c
bd= 541
6

kN

Vc > Vu, safe for BEAM SHEAR

CHECK FOR PUNCHING SHEAR:
Vu = ### kN
Vc =

f'c
bod= ### kN
3

bo = 1.934 m

ING SHEAR

Vc > Vu, safe for PUNCHING SHEAR

Rn =

Mu
= 1.399 MPa
fbd2

2000

act = 0.0035
rmin = 1.4/fy = 0.0034
As = 2939 mm2
USE :

15 - 16 mm bar

2000

15 -16mm bar
BOTHWAYS

NG SHEAR

FAIRMART - Renovation Project

DESIGN OF SQUARE FOOTING
INPUT DATA:
Concrete Strength,
Steel Yield Strength,
Reduction Factor,
Column Size,

P
f'c
fy
f
b
h
Ps
PDL
PLL
PSUR

=
=
=
=
=
=
=
=
=

Allowable Soil Pressure,

Service Deadload,
Service Liveload,
Service Surcharge,
Assume average weight of soil
and concrete above footing base
=
Height of Soil,
Hs =

3000 psi
40000 psi
0.85
12 in
12 in
3.13 ksf
19 kips
31 kips
100 psf

Surcharge
Floor Elev.
Hs
L

130 pcf
5 ft

BASE AREA:(Using Service Loads w/ Net Permissible Soil Pressure)

Total Weight of Surcharge =
0.75 ksf
Net Permissible Soil Pressure =
2.38 ksf
Req'd. Base Area, Af = 21.0084 ft2
L = B = 4.58349 ft
USE

3.0 x 3.0
Af = 9.00

ft. SQUARE FOOTING

ft2

To proportion the footing for strength (depth and req'd. rebar),

factored loads are used.
Pu =
79.3 kips
Soil Reaction, qs =
8.81 ksf
DEPTH OF FOOTING:
3.00 ft

12 "+d
d/2

3.00 ft

12 "+d
d
bo for two-way action
bw for beam action

11.12 Determine depth of footing

based on shear strength w/o
shear reinforcement. Depth
required for shear usually
controls the footing thickness.
Both wide-beam action and
two-way action for strength
computation need to be investigated to determine the
controlling shear criteria for
depth.

Assume t =
deff =
=

12 in
7 in
0.58 ft

1. Wide-beam action:
Vu = qs x tributary area
bw =
3 ft
=
36 in
Tributary area =
1.25 ft2
Vu = 11.0139 kips
fVn = f(2f'cbwd)
=
23.46 kips > Vu OK
2. Two-way action:
Vu = qs x tributary area
(b + d)(h + d)
Tributary area = W x L 144
=

6.49

Vu =

Vc
f'cbod

ft2

57.21 kips
4
2+ b = 6
c
asd
bo + 2 = 6

= minimum of

= 4

bo = 2(b+d) + 2(h+d)
= 76
in
bc = b/d
= 1
bo/d = 10.857
as = 40
fVc =

(for interior columns)

99.07

>

57.21 kips OK

USE : 4

FOOTING REINFORCEMENT:
3 ft
18 in

0.00

Critical section for moment

(long projection)

12 in

d= 7 in
qs = 8.81

1. Critical section for moment is at face of column

Pu = 79.3
kips
qs = 8.81
ksf
Mu = 0.00
ft-kips

2. As required
Required Rn =

r =

Mu
fbd2

= 0

0.85f'c
fy

( 1-

psi

1 - 2Rn/0.85f'c

= 0.00
r(gross area) =

d/h x 0.0025 = 0.0000

rmin = 0.00
Required As = rbd

= 0.45

in2

USING # 6 bars:
As = 0.4418 in2
PROVIDE : 5 -# 6

bars each way

ksf

3. Check development reinforcement

Critical section for development is the same
as that for moment (at face of column).
ld
db

3fyabgl
40f'c ((c+Ktr)/db)

Clear cover (bottom and side)=

3.0 in

Center-to-center bar spacing= 7.31 in

c = 3.38 in
c = 3.66 in
USE c = 3.38 in
Ktr = 0
c + Ktr
db

= 3.4
a
b
ab
g
l

ld
db

=
=
=
=
=

1.0
1.0
1.0
1.0
1.0

= 22

ld = 16

(no transverse reinforcement)

>

2.5 USE 2.5

(less than 12 in. of concrete below bars)

(uncoated reinforcement)
< 1.7
(larger than #7 bars)
(normal weight concrete)