Isolated Footing 14

Input Values

Footing Geomtery
Design Type : Calculate Dimension
Footing Thickness (Ft) : 305.000mm
Footing Length - X (Fl) : 1000.000mm
Footing Width - Z (Fw) : 1000.000mm
Eccentricity along X (Oxd) : 0.000mm
Eccentricity along Z (Ozd) : 0.000mm

Column Dimensions

umn Shape : Rectangular

umn Length - 0.400m

X (Dcol) :

lumn Width - 0.400m

Z (Bcol) :

ude Pedestal?

Pedestal
No

destal Shape : N/A

edestal Height N/A

(Ph) :

destal Length - N/A

X (Pl) :

estal Width - Z N/A

(Pw) :

Design Parameters
Concrete and Rebar Properties
Unit Weight of Concrete :

25.000kN/m3

Strength of Concrete : 20.700N/mm2

Yield Strength of Steel : 275.000N/mm2

Minimum Bar Size : #16

Maximum Bar Size : #20
Pedestal Minimum Bar Size : #12
Pedestal Maximum Bar Size : #32
Minimum Bar Spacing : 50.000mm
Maximum Bar Spacing : 450.000mm
Pedestal Clear Cover (P, CL) : 50.000mm
Bottom Footing Clear Cover (F, CL) : 75.000mm

Soil Properties
Soil Type : Drained
Unit Weight : 22.000kN/m3
Soil Bearing Capacity : 190.000kN/m2
Soil Bearing Capacity Type:

Gross Bearing Capacity

Soil Surcharge : 0.000kN/m2

Depth of Soil above Footing : 0.000mm
Cohesion : 0.000kN/m2

Sliding and Overturning

Coefficient of Friction :0.500
Factor of Safety Against Sliding :1.500
Factor of Safety Against Overturning :1.500

Global Settings
Top Reinforcement Option :Always calculate based on self weight
Concrete Design Option :Gross Pressure
Top Reinforcement Factor :1.000
------------------------------------------------------

Design Calculations
Footing Size

Initial Length (Lo) =

1.000m

Initial Width (Wo) =

1.000m

Load Combination/s- Service Stress Level

Load
Combinatio
n Number

Load Combination Title

Load
Soil
Self
Combinatio Bearing Weight
n Factor
Factor Factor

1.508DL + 1.4EQX + 1.0LL

1.00

1.00

1.00

10

1.508DL + 1.4EQZ + 1.0LL

1.00

1.00

1.00

Load Combination/s- Strength Level

Load
Combinatio
n Number

Load Combination Title

Load
Soil
Self
Combinatio Bearing Weight
n Factor
Factor Factor

1.508DL + 1.4EQX + 1.0LL

1.00

1.00

1.00

10

1.508DL + 1.4EQZ + 1.0LL

1.00

1.00

1.00

Applied Loads - Service Stress Level

LC

Axial
(kN)

Shear X
(kN)

Shear Z
(kN)

Moment X
(kNm)

Moment Z
(kNm)

699.729

22.340

5.912

13.848

-60.243

10

700.457

-0.904

30.975

79.531

1.943

Applied Loads - Strength Level

LC

Axial
(kN)

Shear X
(kN)

Shear Z
(kN)

Moment X
(kNm)

Moment Z
(kNm)

699.729

22.340

5.912

13.848

-60.243

10

700.457

-0.904

30.975

79.531

1.943

Reduction of force due to buoyancy =

0.000kN

Effect due to adhesion = 0.000kN

Area from initial length and width, Ao =Lo X Wo = 1.000m2
Min. area required from bearing pressure,
P / qmax = 3.934m2
Amin =

Note: Amin is an initial estimation.

P = Critical Factored Axial Load(without self
weight/buoyancy/soil).
qmax = Respective Factored Bearing Capacity.

Final Footing Size

Length (L2) =

2.300 m

Governing Load Case :

#9

Width (W2) =

2.300 m

Governing Load Case :

#9

Depth (D2) =

0.355 m

Governing Load Case :

# 10

Depth is governed by Ultimate Load Case

(Service check is performed with footing thickness requirements from concrete check)
Area (A2) =
Final Soil Height =
Footing Self Weight =

5.290 m2
0.000 m
46.94
kN
7

Soil Weight On Top Of

0.000 kN
Footing =

Pressures at Four Corners

Please note that pressures values displayed in tables below are calculated
after dividing by soil bearing factor

Load Case

Pressure Pressure at Pressure

Pressure
at corner 1
corner 2
at corner 3 at corner 4
(q1)
(q2)
(q3)
(q4)
(kN/m2)
(kN/m2)
(kN/m2)
(kN/m2)

Area of
footing in
uplift (Au)
(m2)

99.6651

166.9039

182.6323

115.3934

0.000

99.6651

166.9039

182.6323

115.3934

0.000

10

97.7598

95.5268

184.8126

187.0456

0.000

10

97.7598

95.5268

184.8126

187.0456

0.000

If Au is zero, there is no uplift and no pressure adjustment is necessary.

Otherwise, to account for uplift, areas of negative pressure will be set to zero
and the pressure will be redistributed to remaining corners.

Summary of Adjusted Pressures at 4 corners Four Corners

Load Case

Pressure at
corner 1 (q1)
(kN/m2)

Pressure at
corner 2 (q2)
(kN/m2)

Pressure at
corner 3 (q3)
(kN/m2)

Pressure at
corner 4 (q4)
(kN/m2)

99.6651

166.9039

182.6323

115.3934

99.6651

166.9039

182.6323

115.3934

10

97.7598

95.5268

184.8126

187.0456

10

97.7598

95.5268

184.8126

187.0456

Check for stability against overturning and sliding

Factor of safety against
sliding

Factor of safety
against overturning

Load
Case
No.

Along XDirectio
n

Along ZDirectio
n

Resultan
t

About XDirection

About ZDirection

16.711

63.146

16.155

53.845

12.595

10

413.351

12.065

12.059

9.494

379.632

Critical Load Case And The Governing Factor Of Safety For

Overturning And Sliding - X Direction
Critical Load Case for Sliding along X-Direction :

Governing Disturbing Force : 22.340kN

Governing Restoring Force : 373.702kN
Minimum Sliding Ratio for the Critical Load Case :

16.711

Critical Load Case for Overturning about X- 10

Direction :
Governing Overturning Moment : 90.527kNm
Governing Resisting Moment : 859.499kNm
Minimum Overturning Ratio for the Critical Load 9.494
Case :

Critical Load Case And The Governing Factor Of Safety For

Overturning And Sliding - Z Direction
Critical Load Case for Sliding along Z-Direction :

10

Governing Disturbing Force : 30.975kN

Governing Restoring Force : 373.702kN
Minimum Sliding Ratio for the Critical Load Case :

12.065

Critical Load Case for Overturning about Z- 9

Direction :
Governing Overturning Moment : -68.173kNm
Governing Resisting Moment : 859.499kNm
Minimum Overturning Ratio for the Critical Load 12.595
Case :

Critical Load Case And The Governing Factor Of Safety For Sliding Along Resultant
Direction
Critical Load Case for Sliding along Resultant 10
Direction :
Governing Disturbing Force : 30.988kN
Governing Restoring Force : 373.702kN
Minimum Sliding Ratio for the Critical Load 12.059
Case :

Compression Development Length Check

Development length skipped as column reinforcement is not specified in input (Column Dimnesion
Task Pane)

Shear Calculation
Punching Shear Check

Total Footing Depth, D = 0.355m

Calculated Effective Depth, deff = D - Ccover - 0.5 * db =
For rectangular column,

= Bcol / Dcol =

Effective depth, deff, increased until 0.75XVc

0.270m
1.000

Punching Shear Force

Punching Shear Force, Vu = 683.601kN, Load Case # 10

From ACI Cl.11.12.2.1, bo for column=

2.680m

Equation 11-33, Vc1 =

1640.192kN

Equation 11-34, Vc2 =

1648.352kN

Equation 11-35, Vc3 =

1093.461kN

Punching shear strength, Vc =

0.75 X minimum of (Vc1, Vc2, Vc3)

=

820.096kN

0.75 X Vc > Vu hence, OK

One-Way Shear Check

Along X Direction

(Shear Plane Parallel to Global X Axis)

469.209k
N

From ACI Cl.11.3.1.1, Vc =

Distance along X to design for
shear, Dx =

0.680m

Check that 0.75 X Vc > Vux where Vux is the shear force for the critical load
cases at a distance deff from the face of the column caused by bending about
the X axis.
From above calculations,

0.75 X Vc =

351.90 kN
7
270.15
kN
0

Critical load case for Vux is # 10

0.75 X Vc > Vux hence, OK

One-Way Shear Check

Along Z Direction
(Shear Plane Parallel to Global Z Axis)

From ACI Cl.11.3.1.1, Vc =

472.685 kN
0.67
m
8

Distance along X to design for shear, Dz =

Check that 0.75 X Vc > Vuz where Vuz is the shear force for the critical load
cases at a distance deff from the face of the column caused by bending about
the Z axis.
From above calculations,

0.75 X Vc =

354.51 kN
3
257.07
kN
9

Critical load case for Vuz is # 9

0.75 X Vc > Vuz hence, OK

Design for Flexure about Z Axis

(For Reinforcement Parallel to X Axis)

Calculate the flexural reinforcement along the X direction of the footing. Find
the area of steel required, A, as per Section 3.8 of Reinforced Concrete
Design (5th ed.) by Salmon and Wang (Ref. 1)
Critical Load Case # 9
The strength values of steel and concrete used in the formulae are in ksi
Bars parallel to X Direction are placed at bottom
Effective Depth deff=
Factor

0.272 m
0.850

from ACI Cl.10.2.7.3 =

From ACI Cl. 10.3.2,

0.0372
9

From ACI Cl. 10.3.3,

0.0279
7

From ACI Cl. 7.12.2,

0.0020
0

From Ref. 1, Eq. 3.8.4a, constant m =

15.629

Calculate reinforcement ratio for critical load case

Design for flexure about Z axis is

1.350 m

performed at the face of the

column at a distance, Dx =
Ultimate moment,

171.79
kNm
8

Nominal moment capacity, Mn =

190.88
kNm
7

(Based on effective depth)

Required =

0.0042
2

(Based on gross depth) x deff / Depth =

Since

min max

0.0032
3
OK
2639.0 mm2
05

Area of Steel Required, As =

Selected bar Size = #16

Minimum spacing allowed (Smin) = = 50.000mm
Selected spacing (S) = 164.154mm
Smin<= S <= Smax and selected bar size < selected maximum bar size...
The reinforcement is accepted.
According to ACI 318 Clause No- 10.6.4
Max spacing for Cracking Consideration = 385.642mm
Safe for Cracking Aspect.
Based on spacing reinforcement increment; provided reinforcement
is
#16 @ 190.000mm o.c.

Required development length for bars

=

=0.30
m
5

Available development length for bars,

DL =

0.875 m

Try bar size

# 16

Number of bars required, Nbar =

Area of one bar =

201.06 mm
4 2
14

Because the number of bars is rounded up, make sure new

reinforcement ratio < max

Total reinforcement area, As_total =

deff =

Nbar X (Area of one bar) =

D - Ccover - 0.5 X (dia. of one
bar) =

Reinforcement ratio, =

2814.8
98 mm2
0.272 m
0.0045
0

From ACI Cl.7.6.1, minimum req'd clear distance between bars

Cd = max (Diameter of one bar, 1.0" (25.4mm), Min. User Spacing) = 50.000mm
Provided Steel Area / Required Steel Area = 1.067

Check to see if width is sufficient to accomodate bars

Design for Flexure about X axis

(For Reinforcement Parallel to Z Axis)

Calculate the flexural reinforcement along the Z direction of the footing. Find
the area of steel required, A, as per Section 3.8 of Reinforced Concrete
Design (5th ed.) by Salmon and Wang (Ref. 1)

Critical Load Case # 10

The strength values of steel and concrete used in the formulae are in ksi
Bars parallel to X Direction are placed at bottom
Effective Depth deff=
Factor

0.256 m
0.850

from ACI Cl.10.2.7.3 =

From ACI Cl. 10.3.2,

0.0372
9

From ACI Cl. 10.3.3,

0.0279
7

From ACI Cl.7.12.2,

0.0020
0

From Ref. 1, Eq. 3.8.4a, constant m =

15.629

Calculate reinforcement ratio for critical load case

Design for flexure about X axis is
performed at the face of the
column at a distance, Dz =

1.350 m

Ultimate moment,

180.23
kNm
9

Nominal moment capacity, Mn =

200.26
kNm
5

(Based on effective depth)

Required =

0.0050
3

(Based on gross depth) x deff / Depth =

Since
Area of Steel Required, As =

min max

0.0036
3
OK
2961.0 mm2
99

Selected Bar Size = #16

Minimum spacing allowed (Smin) = 50.000mm
Selected spacing (S) = 152.429mm
Smin<= S <= Smax and selected bar size < selected maximum bar size...

The reinforcement is accepted.

According to ACI 318 Clause No- 10.6.4
Max spacing for Cracking Consideration = 385.642mm
Safe for Cracking Aspect.
Based on spacing reinforcement increment; provided reinforcement
is
#16 @ 300.000mm o.c.

Required development length for bars

=

0.305 m

Available development length for bars,

DL =

0.875 m

Try bar size

# 16

Area of one bar =

201.06
4 mm2

Number of bars required, Nbar =

15

Because the number of bars is rounded up, make sure new

reinforcement ratio < max

Total reinforcement area, As_total =

deff =

Reinforcement ratio, =

Nbar X (Area of one bar) =

D - Ccover - 1.5 X (dia. of one
bar) =

3015.9
62 mm2
0.256 m
0.0051
2

From ACI Cl.7.6.1, minimum req'd clear distance between bars

Cd = max (Diameter of one bar, 1.0" (25.4mm), Min. User Spacing) = 50.000mm
Provided Steel Area / Required Steel Area = 1.019

Check to see if width is sufficient to accomodate bars

Bending moment for uplift cases will be calculated based solely on

selfweight, soil depth and surcharge loading.

As the footing size has already been determined based on all servicebility
load cases, and design moment calculation is based on selfweight, soil depth
and surcharge only, top reinforcement value for all pure uplift load cases will
be the same.

Design For Top Reinforcement Parallel to Z Axis

Top reinforcement is calculated based on self weight of footing and soil

Calculate the flexural reinforcement for Mx. Find the area of steel
required
The strength values of steel and concrete used in the formulae are in ksi
Bars parallel to X Direction are placed at bottom
Effective Depth deff=
Factor

from ACI Cl.10.2.7.3 =

0.256 m
0.850

From ACI Cl. 10.3.2,

0.0372
9

From ACI Cl. 10.3.3,

0.0279
7

From ACI Cl. 7.12.2,

0.0020
0

From Ref. 1, Eq. 3.8.4a, constant m =

15.629

Calculate reinforcement ratio for critical load case

Design for flexure about
X axis is performed at
the face of the column
at a distance, Dx =

0.950 m

Ultimate moment,

9.211 kNm

Nominal moment
capacity, Mn =

10.234 kNm

(Based on effective
depth) Required =

0.0002
5

(Based on gross depth) x deff / Depth =

Since

min

Area of Steel Required,

As =
Total reinforcement
area, As_total =

0.0001
8
min Governs
1633.0 mm2
00

Nbar X (Area of one bar) =

1809.5
56 mm2

Provided Steel Area / Required Steel Area = 1.108

Selected bar Size = #16

Minimum spacing allowed (Smin) = 50.000mm
Selected spacing (S) = 266.750mm
Smin<= S <= Smax and selected bar size < selected maximum bar size...
The reinforcement is accepted.
According to ACI 318 Clause No- 10.6.4
Max spacing for Cracking Consideration = 385.642mm
Safe for Cracking Aspect.
Based on spacing reinforcement increment; provided reinforcement
is
#16 @ 265.000mm o.c.

Design For Top Reinforcement Parallel to X Axis

Top reinforcement is calculated based on self weight of footing and soil

Calculate the flexural reinforcement for Mz. Find the area of steel
required
The strength values of steel and concrete used in the formulae are in ksi
Bars parallel to X Direction are placed at bottom
Effective Depth deff=
Factor

from ACI Cl.10.2.7.3 =

0.272 m
0.850

From ACI Cl. 10.3.2,

0.0372
9

From ACI Cl. 10.3.3,

0.0279
7

From ACI Cl.7.12.2,

0.0020
0

From Ref. 1, Eq. 3.8.4a, constant m =

15.629

Calculate reinforcement ratio for critical load case

Design for flexure about

Z axis is performed at
the face of the column
at a distance, Dx =

0.950 m

Ultimate moment,

9.211 kNm

Nominal moment
capacity, Mn =

10.234 kNm

(Based on effective
depth)Required =

0.0002
19

(Based on gross depth) x deff / Depth =

Since

min

Area of Steel Required,

As =
Total reinforcement
area, As_total =

0.0001
68
min Governs
1633.0 mm2
00

Nbar X (Area of one bar) =

1809.5
56 mm2

Provided Steel Area / Required Steel Area = 1.108

Selected bar Size = #16

Minimum spacing allowed (Smin) = 50.000mm
Selected spacing (S) = 266.750mm
Smin<= S <= Smax and selected bar size < selected maximum bar size...
The reinforcement is accepted.
According to ACI 318 Clause No- 10.6.4
Max spacing for Cracking Consideration = 385.642mm
Safe for Cracking Aspect.
Based on spacing reinforcement increment; provided reinforcement
is
#16 @ 265.000mm o.c.