Isolated Footing Design(ACI 318-14) - Metric · Isolated Footing Design(ACI 318-14) - Metric Footing No. Group ID Foundation Geometry - - Length Width Thickness 1 1 2.80m 2.80m 0.50m

Isolated Footing Design(ACI 318-14) - Metric

Footing No. Group ID Foundation Geometry - - Length Width Thickness 1 1 2.80m 2.80m 0.50m

Footing No.

Footing Reinforcement Pedestal Reinforcement

- Bottom Reinforcement

(Mz) Bottom Reinforcement

(Mx) Top Reinforcement

(Mz) Top Reinforcement

(Mx) Main Steel Trans Steel

1 13 - 16 mm 13 - 16 mm 13 - 16 mm 13 - 16 mm 12-#22 + 16-#19

10 mm @ 300 mm

Isolated Footing 1

1.55 m 2.05 m

0.5 m

1.3 m

Elevation

1.4 m

2.8 m

0.95 m

0.95 m

X

Z

Plan

Input Values

Footing Geomtery

Design Type : Set Dimension

Minimum Footing Length - X(Fl) : 2800.00 mm

Minimum Footing Width - Z (Fw) : 2800.00 mm

Footing Thickness (Ft) : 500.00 mm

Eccentricity along X (Oxd) : 0.00 mm

Eccentricity along Z (Ozd) : 0.00 mm

Column Dimensions

Column Shape : Rectangular

Column Length - X (Dcol) : 0.30 m

Column Width - Z (Bcol) : 0.30 m

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Pedestal

Include Pedestal : Yes

Pedestal Shape : Rectangular

Pedestal Height (Ph) : 1.55 m

Pedestal Length - X (Pl) : 0.95 m

Pedestal Width - Z (Pw) : 0.95 m

Design Parameters

Concrete and Rebar Properties

Unit Weight of Concrete : 25.00 kN/m3

Strength of Concrete : 25.30 N/mm2

Yield Strength of Steel : 420.00 N/mm2

Minimum Bar Size : 16 mm

Maximum Bar Size : 25 mm

Top Footing Minimum Bar Size : 16 mm

Top Footing Maximum Bar Size : 25 mm

Pedestal Minimum Bar Size : 16 mm

Pedestal Maximum Bar Size : 25 mm

Minimum Bar Spacing : 100.00 mm

Maximum Bar Spacing : 250.00 mm

Pedestal Clear Cover (P, CL) : 50.00 mm

Bottom Footing Clear Cover (F, CL) : 50.00 mm

Soil Properties

Soil Type : Cohesionless Soil

Unit Weight : 20.00kN/m3

Base Value of Soil Bearing Capacity : 120.00kPa

Multiplying factor for soil bearing capacity for ultimate loads : 1.00

Soil Bearing Capacity Type : Gross Bearing Capacity

Soil Surcharge : 0.00kN/m2

Height of Soil above Footing : 1.30m

Type of Depth : Fixed Top

Undrained Shear Strength : 0.00kN/m2

Bearing Capacity Input Method : Fixed Bearing Capacity

Minimum Percentage of Slab area in Contact for Service Loads : 85.00

Minimum Percentage of Slab area in Contact for Ultimate Loads : 85.00

Sliding and Overturning

Coefficient of Friction : 0.50

Factor of Safety Against Sliding : 1.50

Factor of Safety Against Overturning : 1.50

Global Settings

Top Reinforcement Option : Always calculate based on self weight

Concrete Design Option : Net Pressure(Gross Pressure - Self Weight Pressure)

Top Reinforcement Factor : 1.00

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Design Calculations

Footing Size

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Initial Length (Lo) = 2.80 m

Initial Width (Wo) = 2.80 m

Load Combinations

Load Combination/s- Service Stress Level Load

Combination Number

Load Combination Title Load

Combination Factor (a)

Soil Bearing

Factor (b)

Self Weight

Factor (c)

a - Value specified in the Load Safety Factor table b - Value specified in the Pile/Soil Bearing Capacity Factors table c - Value specified in the Apply Self Weight and Dead Weight Factor table

1 Wind,BlnsTension90Wind 1.00 1.00 1.00

2 Ice,BlnsTension90Wind 1.00 1.00 1.00

3 LowTemp,BlnsTension 1.00 1.00 1.00

4 BreakWire,UnBlnsTension, 1.00 1.00 1.00

5 ABreakWire,UnBlnsTension, 1.00 1.00 1.00

6 CreakWire,UnBlnsTension, 1.00 1.00 1.00

7 UnBLnsIce 1.00 1.00 1.00

8 SetUp 1.00 1.00 1.00

9 ASetUp 1.00 1.00 1.00

10 LongTime 1.00 1.00 1.00

Load Combination/s- Strength Level Load

Combination Number

Load Combination Title Load

Combination Factor (a)

Soil Bearing

Factor (b)

Self Weight

Factor (c)

a - Value specified in the Load Safety Factor table b - Value specified in the Pile/Soil Bearing Capacity Factors table c - Value specified in the Apply Self Weight and Dead Weight Factor table

51 Wind,BlnsTension90Wind 1.00 1.00 1.00

52 Ice,BlnsTension90Wind 1.00 1.00 1.00

53 LowTemp,BlnsTension 1.00 1.00 1.00

54 BreakWire,UnBlnsTension, 1.00 1.00 1.00

55 ABreakWire,UnBlnsTension, 1.00 1.00 1.00

56 CreakWire,UnBlnsTension, 1.00 1.00 1.00

57 UnBLnsIce 1.00 1.00 1.00

58 SetUp 1.00 1.00 1.00

59 ASetUp 1.00 1.00 1.00

60 LongTime 1.00 1.00 1.00

Applied Loads on Top of Pedestal

Before consideration of self weight and load safety factor table

Moments are about the center of footing / pile cap (does not include moments caused by lateral loads)For the loads shown in this table, the sign convention is the same as that for JOINT LOADS in STAAD.Pro when global Y is the vertical axis.

Applied Loads from Column - Service Stress Level

Load Case Fx

(kN)

Fy

(kN) Downwards is

negative Upwards is positive

Fz

(kN) Mx

(kNm) Mz

(kNm)

1 15.10 19.55 -0.02 -0.16 157.96

2 5.98 23.91 -0.02 -0.16 68.73

3 1.62 19.14 -0.03 -0.20 24.20

4 1.29 22.66 -4.79 -58.72 22.27

5 1.29 22.66 -4.79 -48.34 22.86

6 1.17 22.66 -6.59 -99.02 19.68

7 8.08 23.00 -0.02 -0.16 80.42

8 3.02 37.13 -1.75 -25.39 46.47

9 3.02 37.13 -1.75 -23.43 47.19

10 3.64 19.16 -0.02 -0.16 37.34

Applied Loads from Column - Strength Level

Load Case Fx

(kN)

Fy

(kN) Downwards is


Fz

(kN) Mx

(kNm) Mz

(kNm)

51 15.10 19.55 -0.02 -0.16 157.96

52 5.98 23.91 -0.02 -0.16 68.73

53 1.62 19.14 -0.03 -0.20 24.20

54 1.29 22.66 -4.79 -58.72 22.27

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Applied Loads from Column - Strength Level

Load Case Fx

(kN)

Fy

(kN) Downwards is


Fz

(kN) Mx

(kNm) Mz

(kNm)

55 1.29 22.66 -4.79 -48.34 22.86

56 1.17 22.66 -6.59 -99.02 19.68

57 8.08 23.00 -0.02 -0.16 80.42

58 3.02 37.13 -1.75 -25.39 46.47

59 3.02 37.13 -1.75 -23.43 47.19

60 3.64 19.16 -0.02 -0.16 37.34

Reduction of force due to buoyancy = 0.00 kN

Effect due to adhesion = 0.00 kN

Area from initial length and width, Ao = Lo X Wo = 7.84 m2

Min. area required from bearing pressure, Amin = 4.74 m2

Note: Amin is an initial estimation considering self-weight, axial load and moment against factored bearing capacity.

Final Footing Size

Length (L2) = 2.80 m Governing Load Case : # 0

Width (W2) = 2.80 m Governing Load Case : # 0

Depth (D2) = 0.50 m

Depth is governed by Ultimate Load Case

(Service check is performed with footing thickness requirements from concrete check)

Area (A2) = 7.84 m2

Final Pedestal Height = 1.55 m

Final Soil Height = 1.30 m

Foundation Self Weight = 132.97 kN

Soil Weight On Top Of Footing = 180.37 kN

Gross Pressures at 4 Corners

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

Load Case / Combination

Pressure at top left

corner(kN/m2)

Pressure at top right

corner(kN/m2)

Pressure at bottom

right corner

(kN/m2)

Pressure at bottom left corner(kN/m2)

Area of footing in uplift (Au)

(m2)

Gross Bearing Capacity (kN/m2)

6 72.5570 63.1099 1.5950 11.0421 0.00 120.0000

6 72.5570 63.1099 1.5950 11.0421 0.00 120.0000

3 43.3033 31.8896 31.7467 43.1603 0.00 120.0000

1 72.2419 2.8134 2.7035 72.1320 0.00 120.0000

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 Gross Pressures at four Corners

Load Case / Combination

Pressure at top left corner

(kN/m2)

Pressure at top right corner

(kN/m2)

Pressure at bottom right

corner(kN/m2)

Pressure at bottom left

corner(kN/m2)

Gross Bearing Capacity (kN/m2)

6 72.5570 63.1099 1.5950 11.0421 120.0000

6 72.5570 63.1099 1.5950 11.0421 120.0000

3 43.3033 31.8896 31.7467 43.1603 120.0000

1 72.2419 2.8134 2.7035 72.1320 120.0000

Stability Check

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1.55 m 2.05 m

0.5 m

1.3 m

.

Frictional Force

Sliding Force

OTM

- Factor of safety against sliding Factor of safety against overturning

Load Case No.

Along X-Direction

Along Z-Direction Resultant

Required FOS

About X-Direction

About Z-Direction

Required FOS

1 9.73 7344.65 9.73 1.50 2046.24 3.24 1.50

2 24.20 7235.65 24.20 1.50 2015.87 7.18 1.50

3 90.80 4903.26 90.79 1.50 1575.02 19.73 1.50

4 112.67 30.34 29.30 1.50 5.94 20.74 1.50

5 112.67 30.34 29.30 1.50 7.00 20.13 1.50

6 124.22 22.05 21.71 1.50 3.62 23.55 1.50

7 17.97 7258.40 17.97 1.50 2022.21 6.37 1.50

8 45.73 78.92 39.57 1.50 13.34 9.60 1.50

9 45.73 78.92 39.57 1.50 14.31 9.43 1.50

10 40.41 7354.40 40.41 1.50 2048.96 13.78 1.50

Critical Load Case And The Governing Factor Of Safety For Overturning And Sliding - X Direction

Critical Load Case for Sliding along X-Direction : 1

Governing Disturbing Force : 15.10 kN

Governing Restoring Force : 146.89 kN

Minimum Sliding Ratio for the Critical Load Case : 9.73

Critical Load Case for Overturning about X-Direction : 6

Governing Overturning Moment : -112.53 kNm

Governing Resisting Moment : 406.94 kNm

Minimum Overturning Ratio for the Critical Load Case : 3.62

Critical Load Case And The Governing Factor Of Safety For Overturning And Sliding - Z Direction

Critical Load Case for Sliding along Z-Direction : 6

Governing Disturbing Force : -6.59 kN



Critical Load Case for Overturning about Z-Direction : 1

Governing Overturning Moment : 127.01 kNm

Governing Resisting Moment : 411.29 kNm

Minimum Overturning Ratio for the Critical Load Case : 3.24

Critical Load Case And The Governing Factor Of Safety For Sliding Along Resultant Direction

Critical Load Case for Sliding along Resultant Direction : 1

Governing Disturbing Force : 15.10 kN



Compression Development Length Check

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

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Ultimate Gross Pressures

The base pressures reported in this table do not include the effect of buoyancy. However, the area of footing in contact includes the effect of buoyancy (if any).

Load Case / Load

Combination ID

Pressure at top left corner

(kN/m2)

Pressure at top right corner

(kN/m2)

Pressure at bottom right

corner(kN/m2)

Pressure at bottom left

corner(kN/m2)

Area of footing in

Contact with soil (Au)

(m2)

51 72.2419 2.8134 2.7035 72.1320 7.84

52 52.4067 21.5363 21.4264 52.2968 7.84

53 43.3033 31.8896 31.7467 43.1603 7.84

54 61.1740 50.4455 12.9780 23.7065 7.84

55 58.4981 47.4471 15.6539 26.7049 7.84

56 72.5570 63.1099 1.5950 11.0421 7.84

57 54.5413 19.6338 19.5239 54.4314 7.84

58 54.1601 32.1413 16.3005 38.3194 7.84

59 53.8212 31.4087 16.6395 39.0519 7.84

60 45.7439 29.4108 29.3009 45.6340 7.84

Minimum Required Contact Area for Ultimate Loads : 6.66 m2

Actual Area in Contact for all ultimate load cases exceeds the minimum required. Hence Safe

Gross Bearing Capacity for Ultimate Loads : 120.00 kN/m2

Maximum Corner Pressure from all ultimate load cases is less than the allowable. Hence Safe

Shear Calculation

Punching Shear Check

1.4 m

0.215 m

Plan

X

Z

Total Footing Depth, D = 0.50m

Calculated Effective Depth, d = D - Ccover - 1 * db = 0.43 m

For rectangular column, = Bcol / Dcol = 1.00

Effective depth, d, increased until 0.75XVc Punching Shear Force

Punching Shear Force, Vu = 122.90kN, Load Case # 51

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From ACI Cl. 22.6.5.2, bo for column= = 5.54 m

Table 22.6.5.2, (b), Vc1 = = 6163.69 kN

Table 22.6.5.2, (c), Vc2 = = 5151.81 kN

Table 22.6.5.2, (a), Vc3 = = 3988.51 kN

Punching shear strength, Vc = 0.75 X minimum of (Vc1, Vc2, Vc3) = 2991.38 kN

0.75 X Vc > Vu hence, OK

One-Way Shear Along X

(Shear Plane Parallel to Global X Axis)

1.4 m

0.495 m

0.495 m

Plan

X

Z

From ACI Cl. 22.5.5.1, Vc = = 1019.94 kN

Distance of critical section from top left corner along Z, DZ = = 0.50 m

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

From above calculations, 0.75 X Vc = 764.96 kN

Critical load case for Vux is # 56 = 38.10 kN

0.75 X Vc > Vux hence, OK

One-Way Shear Along Z

(Shear Plane Parallel to Global Z Axis)

1.4 m

0.495 m 0.495 m

Plan

X

Z

From ACI Cl. 22.5.5.1, Vc = = 1019.94 kN

Distance of critical section from top left corner along X, DX = = 0.50 m

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

From above calculations, 0.75 X Vc = 764.96 kN

Critical load case for Vuz is # 51 = 43.23 kN

0.75 X Vc > Vuz hence, OK

Flexure About Z-Axis

Design For Bottom Reinforcement Parallel to X Axis

13 - 16 mm

X

Z

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 # 51

The strength values of steel and concrete used in the formulae are in Mpa

Bars parallel to X Direction are placed at bottom

Effective Depth d = 0.43 m

Factor from ACI Cl. 22.2.2.4.3 = = 0.85

From ACI318-2011 Appendix B 8.4.2, =

= 0.02560

From ACI318-2011 Appendix B 10.3.3, = = 0.01920

From ACI Cl. 25.2.1, = = 0.00180

From Ref.1, Eq. 3.8.4a, constant m = = 19.53

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 = = 0.93 m

Ultimate moment = = 34.78 kNm

Nominal moment capacity, Mn = = 38.64 kNm

(Based on effective depth) Required = = 0.00018

(Based on gross depth) x d / Depth = 0.00015

Since ρ < ρmin, select ρ= ρmin ρmin Governs

Area of Steel Required, As = = 2520.01 mm2

Selected bar Size = 16 mm

Minimum spacing allowed (Smin) = 100.00mm

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Selected spacing (S) = 223.67mm

Smin<= S <= Smax and selected bar size < selected maximum bar size...

The reinforcement is accepted.

According to ACI 318 Clause No- 24.3.2 1st

Max spacing for Cracking Consideration = 254.89mm

Safe for Cracking Aspect.

Based on spacing reinforcement increment; provided reinforcement is

16 mm @ 220mm o.c.

Required development length for bars = = 0.64 m

Available development length for bars,DL = = 0.88 m

Try bar size 16 mm Area of one bar = 201.06 mm2

Number of bars required, Nbar = = 13

Because the number of bars is rounded up, make sure new reinforcement ratio < ρmax

Total reinforcement area, As_total = Nbar X (Area of one bar) = 2613.83 mm2

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

= 0.43 m

Reinforcement ratio, = = 0.00219

From ACI Cl. 25.2.1, minimum req'd clear distance between bars

Cd = max (Diameter of one bar, 1.0" (25.4mm), Min. User Spacing) = 100.00mm

Provided Steel Area / Required Steel Area = 1.04

Design For Top Reinforcement Parallel to X Axis

13 - 16 mm

X

Z

First load case to be in pure uplift # 51

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



Factor from ACI Cl. 22.2.2.4.3 = =

0.85



From ACI Cl. 25.2.1, = = 0.00180

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

= 19.53


Design for flexure about Z axis is performed at the face of the column at a distance, Dx = = 0.93 m



(Based on effective depth)Required = = 0.000241











According to ACI 318 Clause No- 24.3.2 2nd




16 mm @ 220mm o.c.

Flexure About X-Axis

Design For Bottom Reinforcement Parallel to Z Axis

13 - 16 mm

X

Z

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 # 56

The strength values of steel and concrete used in the formulae are in Mpa



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From ACI Cl. 25.2.1, = = 0.00180

From Ref.1, Eq. 3.8.4a, constant m = = 19.53


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

= = 0.93 m







Selected Bar Size = 16 mm





Testing.... Max spacing for Cracking Consideration = 254.89mm



16 mm @ 220mm o.c.

Required development length for bars = = 0.64 m

Available development length for bars, DL = = 0.88 m

Try bar size 16 mm Area of one bar = 201.06 mm2

Number of bars required, Nbar= = 13

Because the number of bars is rounded up, make sure new reinforcement ratio < ρmax


d = D - Ccover - 1.5 X (dia. of one bar) = 0.43 m

Reinforcement ratio, = = 0.00219

From ACI Cl. 25.2.1, minimum req'd clear distance between bars

Cd = max (Diameter of one bar, 1.0" (25.4mm), Min. User Spacing) = 100.00mm


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

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13 - 16 mm

X

Z

First load case to be in pure uplift # 51

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






From ACI Cl. 25.2.1, = = 0.00180

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

= 19.53


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

= = 0.93 m

Ultimate moment, = = 46.12 kNm













According to ACI 318 Clause No- 24.3.2 4th




16 mm @ 220mm o.c.

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Pedestal Design

The bar sizes reported in the output below for the pedestal design are based on the table titled ASTM STANDARD REINFORCING BARS, Appendix E of ACI 318M-11 (The Metric version of the 2011 edition of ACI 318). They are not from the same bar library that has been used in the calculations presented above for the design of this

footing. The next version of the program will use bars from a single library for the design of both components.

Pedestal at Support No. Axial Capacity Ratio Flexural Capacity Ratio % of Main Steel Main Reinforcement Links 1 0.00 0.11 1.02 12-#22 + 16-#19 10 @ 300mm

Longitudinal Reinforcement Details

Area of Longitudinal Bars = 9229.28 sq.mm

Number of Bars and Bar Dia = 12-#22 + 16-#19

Longitudinal Steel Percentage = 1.02

Flexure - Governing Load Case Details

Governing Load Case Number = 51

Critical Location = Top

Shear - Governing Load Case Details

Critical Load Case for Shear Along X = 51

Critical Load Case for Shear Along Z = 56

Transverse Stirrups Details

Rebar Links = 10 @ 300 mm

No. of Legs in X direction = 8

No. of Legs in Z direction = 8

Capacity Ratios

Flexural Capacity Ratio = 0.11

Axial Capacity Ratio = 0.00

Material Take Off

Footing Reinforcement

Direction Size Number Length (m) Weight (kgf)

Along Z on Bottom Face

16 mm 13 35.10 55.42

Along X on Bottom Face

16 mm 13 35.10 55.42

Along Z on Top Face

16 mm 13 35.10 55.42

Along X on Top Face

16 mm 13 35.10 55.42

Total Reinforcement Weight : 221.68 kgf

Concrete

- Length Width Thickness Weight

Footing 2.80m 2.80m 0.50m 98.00kN

Pedestal 0.95m 0.95m 1.55m 34.97kN

Total Concrete Weight : 132.97 kN

Soil Excavation

Pad Depth : 1.80 m

Pad Slope (a : b) : 1 : 1 (Assumed)

Side Distance, s : 0 (Assumed)

Excavation Volume : 40.03 m3

Backfill Volume : 34.71 m3

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1.4 m1.4 m

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Documents

Isolated Footing Design(ACI 318-14) - Metric · Isolated Footing Design(ACI 318-14) - Metric Footing No. Group ID Foundation Geometry - - Length Width Thickness 1 1 2.80m 2.80m 0.50m