pedestal 1

8/20/2019 Pedestal 1

1/14

Isolated Footing Design(ACI 318-05)

Design For Isolated Footing 1

Isolated Footing 1

Input Values

Footing Geomtery

Column Dimensions

Footing No. Group ID Foundation Geometry

- - Length Width Thickness

1 1 4300.000 mm 4300.000 mm 1000.000 mm

Footing No. Footing Reinforcement Pedestal Reinforcement

- Bottom Reinforcement(Mz) Bottom Reinforcement(Mx) Top Reinforcement(Mz) Top Reinforcement(Mx) Main Steel Trans Steel

1 #16 @ 125 mm c/c #25 @ 315 mm c/c #25 @ 315 mm c/c #16 @ 125 mm c/c 28 - #25 #8 @ 380 mm

Design Type : Calculate Dimension

Footing Thickness (Ft) : 1000.000 mm

Footing Length - X (Fl) : 4300.000 mmFooting Width - Z (Fw) : 4300.000 mm

Eccentricity along X (Oxd) : 0.000 mm

Eccentricity along Z (Ozd) : 0.000 mm

Column Shape : Rectangular

Column Length - X (Pl) : 999.998 mm

Column Width - Z (Pw) : 699.999 mm

Page 1 of 14Isolated Footing Design

11/2/2015file:///C:/Staad.foundation%205.3/CalcXsl/footing.xml


2/14

Pedestal

Design Parameters

Concrete and Rebar Properties

Soil Properties

Sliding and Overturning

Design Calculations

Footing Size

Include Pedestal? Yes

Pedestal Shape : Rectangular

Pedestal Height (Ph) : 1100.000 mm

Pedestal Length - X (Pl) : 1000.000 mm

Pedestal Width - Z (Pw) : 600.000 mm

Unit Weight of Concrete : 25.000 kN/m3

Strength of Concrete : 30.000 MPa

Yield Strength of Steel : 420.000 MPa

Minimum Bar Size : #8

Maximum Bar Size : #25

Minimum Bar Spacing : 100.000 mm

Maximum Bar Spacing : 500.000 mm

Pedestal Clear Cover (P, CL) : 75.000 mm

Footing Clear Cover (F, CL) : 75.000 mm

Soil Type : Drained

Unit Weight : 20.000 kN/m3

Soil Bearing Capacity : 200.000 kN/m2

Soil Surcharge : 0.000 kN/m2

Depth of Soil above Footing : 1500.000 mm

Cohesion : 0.000 kN/m2

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

Factor of Safety Against Overturning : 1.500

------------------------------------------------------

Initial Length (Lo) = 4300.000 mm

Initial Width (Wo) = 4300.000 mm

Load Combination/s- Service Stress Level

Load CombinationNumber

Load Combination Title

25 1DL + 1LL(1)

26 1DL + 1LL(R)

27 1DL + 0.6WL(+X)

28 1DL + 0.6WL(+Z)

29 1DL + 0.6WL(-X)

30 1DL + 0.6WL(-Z)

31 1DL + 0.7WL(+X)

32 1DL + 0.7WL(+Z)




3/14

33 1DL + 0.7WL(-X)

34 1DL + 0.7WL(-Z)

35 1DL + 0.45WL(+X) + 0.75LL(1)

36 1DL + 0.45WL(+X) + 0.75LL(R)

37 1DL + 0.45WL(+Z) + 0.75LL(1)

38 1DL + 0.45WL(+Z) + 0.75LL(R)

39 1DL + 0.45WL(-X) + 0.75LL(1)

40 1DL + 0.45WL(-X) + 0.75LL(R)

41 1DL + 0.45WL(-Z) + 0.75LL(1)

42 1DL + 0.45WL(-Z) + 0.75LL(R)

43 1DL + 0.75LL(1)

44 1DL + 0.75LL(R)

Load Combination/s- Strength Level

Load CombinationNumber

Load Combination Title

9 1.4DL

10 1.2(DL + TL) + 1.6LL + 0.5LR

11 1.2DL + 1.6LR + LL

12 1.2DL + 1.6LR + 0.8W(+X)

13 1.2DL + 1.6LR + 0.8W(-X)

14 1.2DL + 1.6LR + 0.8W(+Z)

15 1.2DL + 1.6LR + 0.8W(-Z)

16 1.2DL + 1.6WL(+X) + LL + 0.5LR

17 1.2DL + 1.6WL(-X) + LL + 0.5LR

18 1.2DL + 1.6WL(+Z) + LL + 0.5LR

19 1.2DL + 1.6WL(-Z) + LL + 0.5LR

20 1.2DL + LL

21 0.9DL + 1.6 WL(+X)

22 0.9DL + 1.6 WL(-X)

23 0.9DL + 1.6 WL(+Z)

24 0.9DL + 1.6 WL(-Z)

Applied Loads - Service Stress Level

LC Axial(kN)

Shear X(kN)

Shear Z(kN)

Moment X(kNm)

Moment Z(kNm)

25 1845.640 0.601 -10.870 -22.418 -2.324

26 1376.480 0.472 -7.902 -16.370 -1.587

27 1397.650 0.680 -8.076 -16.917 -4.343

28 1364.140 0.701 68.899 266.485 -3.29929 1397.650 0.085 -8.078 -16.925 3.036

30 1431.160 0.216 -85.017 -300.304 0.074

31 1397.650 0.716 -8.076 -16.916 -4.798

32 1358.550 0.742 81.731 313.720 -3.579

33 1397.650 0.022 -8.079 -16.926 3.812

34 1436.740 0.176 -97.837 -347.533 0.357

35 1733.640 0.730 -10.172 -21.041 -4.285

36 1381.780 0.634 -7.945 -16.504 -3.684

37 1708.380 0.748 47.652 192.272 -3.420

38 1356.640 0.651 49.802 196.095 -2.862

39 1733.650 0.288 -10.174 -21.048 1.489

40 1381.780 0.189 -7.946 -16.510 1.954

41 1758.910 0.385 -67.978 -234.347 -0.877

42 1406.930 0.287 -65.673 -229.098 -0.334

43 1733.640 0.566 -10.173 -21.043 -2.150

44 1381.780 0.469 -7.945 -16.506 -1.599

Applied Loads - Strength Level

LC Axial(kN)

Shear X(kN)

Shear Z(kN)

Moment X(kNm)

Moment Z(kNm)

9 1956.730 0.643 -11.302 -23.691 -2.273

10 2346.890 -16.299 -48.202 241.528 99.895

11 2091.280 0.711 -12.202 -24.913 -2.472

12 1643.270 0.844 -9.410 -19.422 -6.042




4/14

Final Footing Size

Pressures at Four Corners

If A u 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

13 1643.280 0.086 -9.415 -19.438 5.400

14 1598.400 0.891 93.347 359.379 -3.978

15 1688.150 0.237 -112.111 -398.214 0.360

16 2114.621 1.263 -12.391 -25.510 -11.227

17 2114.630 -0.258 -12.402 -25.548 12.038

18 2024.230 1.344 193.708 736.099 -7.138

19 2205.010 0.057 -218.241 -787.007 1.900

20 2125.190 0.693 -12.482 -25.801 -2.644

21 1257.880 1.002 -7.268 -15.220 -8.673

22 1257.890 -0.590 -7.273 -15.241 10.857

23 1168.700 1.062 197.959 739.551 -5.927

24 1347.070 -0.236 -212.247 -769.863 3.051

Reduction of force due to buoyancy = 0.000 kN

Effect due to adhesion = 0.000 kN

Area from initial length and width, A o =Lo X Wo = 18490000.000 mm2

Min. area required from bearing pressure, A min

=P / qmax = 14305272.924 mm2

Note: Amin is an initial estimation.

P = Critical Factored Axial Load(without self weight/buoyancy/soil).q

max= Respective Factored Bearing Capacity.

Length (L2) = 4300.000 mm Governing Load Case : # 25

Width (W2) = 4300.000 mm Governing Load Case : # 25

Depth (D2) = 1000.000 mm Governing Load Case : # 25

Area (A 2) = 18490000.000 mm2

Load Case

Pressure atcorner 1

(q1)

(kN/mm2)

Pressure atcorner 2

(q2)

(kN/mm2)

Pressure atcorner 3

(q3)

(kN/mm2)

Pressure atcorner 4

(q4)

(kN/mm2)

Area of footingin uplift (A

u)

(mm2)

41 0.0002 0.0002 0.0001 0.0001 0.000

41 0.0002 0.0002 0.0001 0.0001 0.000

37 0.0001 0.0001 0.0002 0.0002 0.000

37 0.0001 0.0001 0.0002 0.0002 0.000

Pressure at Pressure at Pressure at Pressure at




5/14

Check for stability against overturning and sliding

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

Load Case

corner 1 (q1)

(kN/mm2)

corner 2 (q2)

(kN/mm2)

corner 3 (q3)

(kN/mm2)

corner 4 (q4)

(kN/mm2)

41 0.0002 0.0002 0.0001 0.0001

41 0.0002 0.0002 0.0001 0.0001

37 0.0001 0.0001 0.0002 0.0002

37 0.0001 0.0001 0.0002 0.0002

-Factor of safety against

slidingFactor of safety against

overturning

Load CaseNo.

Along X-Direction

Along Z-Direction

About X-Direction

About Z-Direction

25 2380.244 131.603 135.955 1715.308

26 2533.786 151.347 156.005 1994.637

27 1774.312 149.397 153.147 898.993

28 1697.257 17.268 12.442 1072.298

29 14194.494 149.360 153.092 1815.604

30 5663.366 14.389 10.985 13857.044

31 1685.101 149.397 153.151 823.297

32 1599.706 14.523 10.516 993.542

33 54842.362 149.342 153.077 1377.685

34 6966.346 12.532 9.534 418422.766

35 1882.914 135.128 139.391 1015.893

36 1890.531 150.862 155.294 1027.628

37 1820.718 28.580 20.032 1173.390

38 1821.854 23.815 16.961 1205.910

39 4772.681 135.102 139.354 6684.560

40 6341.783 150.843 155.256 3309.978

41 3603.018 20.406 15.817 3538.889

42 4220.112 18.442 14.190 5559.987

43 2428.493 135.115 139.377 1770.343

44 2555.644 150.862 155.284 1994.646

Critical Load Case for Sliding along X-Direction : 32

Governing Disturbing Force : 0.742 kN




6/14

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

Shear Calculation

Punching Shear Check

Effective depth, deff

, increased until 0.75XVc

Punching Shear Force

Punching Shear Force, Vu = 1985.320 kN, Load Case # 10

Along X Direction

(Shear Plane Parallel to Global X Axis)

Governing Restoring Force : 1186.982 kN

Minimum Sliding Ratio for the Critical Load Case : 1599.706

Critical Load Case for Overturning about X-Direction : 34

Governing Overturning Moment : -552.987 kNm

Governing Resisting Moment : 5272.036 kNm

Minimum Overturning Ratio for the Critical Load Case : 9.534

Critical Load Case for Sliding along Z-Direction : 34

Governing Disturbing Force : -97.837 kN

Governing Restoring Force : 1226.077 kN

Minimum Sliding Ratio for the Critical Load Case : 12.532

Critical Load Case for Overturning about Z-Direction : 31

Governing Overturning Moment : -6.301 kNm

Governing Resisting Moment : 5187.994 kNm

Minimum Overturning Ratio for the Critical Load Case : 823.297

Total Footing Depth, D = 1000.000mm

Calculated Effective Depth, deff = D - Ccover - 1.0 = 899.600mm

1 inch is deducted from total depth to cater bar dia(US Convention).

For rectangular column, = Bcol / Dcol = 1.667

From ACI Cl.11.12.2.1, bo for column= 6798.400 mm

Equation 11-33, Vc1

= 12238.523 kN

Equation 11-34, Vc2 = 20285.380 kN

Equation 11-35, Vc3

= 11125.930 kN

Punching shear strength, Vc = 0.75 X minimum of (V

c1, V

c2, V

c3) = 8344.448 kN

0.75 X Vc > Vu hence, OK




7/14

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.

One-Way Shear Check

Along Z Direction

(Shear Plane Parallel to Global Z Axis)

Check that 0.75 X V c > V uz 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.

Design for Flexure about Z Axis

(For Reinforcement Parallel to X Axis)

From ACI Cl.11.3.1.1, Vc = 3518.585 kN

Distance along X to design for shear,Dx =

950.400 mm

From above calculations, 0.75 X Vc = 2638.939 kN

Critical load case for Vux is # 19 786.536 kN

0.75 X Vc > Vux hence, OK

From ACI Cl.11.3.1.1, Vc = 3518.585 kN

Distance along X to design for shear, Dz = 750.400 mm

From above calculations, 0.75 X Vc = 2638.939 kN

Critical load case for Vuz

is # 10 436.520 kN

0.75 X Vc > V

uz hence, OK




8/14

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 ConcreteDesign (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

Calculate reinforcement ratio for critical load case

Based on spacing reinforcement increment; provided reinforcement is

Factor from ACI Cl.10.2.7.3 = 0.832

From ACI Cl. 10.3.2, = 0.02973

From ACI Cl. 10.3.3, = 0.02230

From ACI Cl. 7.12.2, = 0.00177

From Ref. 1, Eq. 3.8.4a, constant m = 16.471

Design for flexure about Z axis isperformed at the face of the column

at a distance, Dx =1650.000 mm

Ultimate moment, 787.018 kNm

Nominal moment capacity, Mn = 874.465 kNm

Required = 0.00060

Since OK

Area of Steel Required, A s = 6858.221 mm2

Selected bar Size = #25

Minimum spacing allowed (Smin) = = 100.000 mm

Selected spacing (S) = 317.308 mm

Smin


9/14

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

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 ConcreteDesign (5th ed.) by Salmon and Wang (Ref. 1)

Critical Load Case # 19



Required development length for bars = =304.800 mm

Available development length for bars, DL

=1575.000 mm

Try bar size # 25 Area of one bar = 490.870 mm2

Number of bars required, Nbar = 14

Total reinforcement area, A s_total

= Nbar

X (Area of one bar) = 6872.180 mm2

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

=

912.500 mm

Reinforcement ratio, = 0.00175

From ACI Cl.7.6.1, minimum req'd cleardistance between bars, C

d =

max (Diameter of one bar, 1.0,Min. User Spacing) =

317.308 mm


From ACI Cl. 10.3.2, = 0.02973

From ACI Cl. 10.3.3, =0.02230

From ACI Cl.7.12.2, = 0.00177


Design for flexure about X axis isperformed at the face of the column

at a distance, Dz =1850.000 mm





10/14


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

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 depthand surcharge only, top reinforcement value for all pure uplift load cases will be the same.

Design For Top Reinforcement Parallel to Z Axis


Required = 0.00111

Since OK


Selected Bar Size = #16Minimum spacing allowed (Smin) = 100.000 mm


Smin


11/14

Calculate the flexural reinforcement for M x. Find the area of steel required




Design For Top Reinforcement Parallel to X Axis


From ACI Cl. 10.3.2, = 0.02973

From ACI Cl. 10.3.3, = 0.02230

From ACI Cl. 7.12.2, = 0.00177


Design for flexure about A axis isperformed at the face of the column

at a distance, Dx =

1850.000 mm



Required = 0.00033

Since OK



Minimum spacing allowed (Smin) = 100.000 mm


Smin


12/14

First load case to be in pure uplift #

Calculate the flexural reinforcement for Mz. Find the area of steel required




Pedestal Design Calculations


From ACI Cl. 10.3.2, = 0.02973

From ACI Cl. 10.3.3, = 0.02230

From ACI Cl.7.12.2, = 0.00177


Design for flexure about A axis isperformed at the face of the column

at a distance, Dx =

1650.000 mm



Required = 0.00025

Since OK



Minimum spacing allowed (Smin) = 100.000 mm


Smin


13/14

Strength and Moment Along Reinforcement in X direction

Strength and Moment from Concrete

Calculate strength and moment from one bar.

Strength and Moment Along Reinforcement in Z direction

Strength and Moment from Concrete

Calculate strength and moment from one bar.

Critical Load Case: 10

Bar size : 25 mm

Number of Bars : 28

Steel Area : 12449.9994 sq.mm

Neutral Axis Depth (Xb): 76.9150 mm

Cc = 1632.698 kN

Mc = 437.533 kNm

Distance between extreme fiber andbar,

db 87.500 mm

Strain in bar, = -0.0004

Maximum Strain, = 0.0021

as

-0.083 kN/mm2

0.0020

as

0.000 kN/mm2

-40.521 kN

-8.611 kNm

Total Bar Capacity, Cs = -3129.443

kN

Capacity of Column = Cc + Cs =-

1496.745kN

Total Bar Moment, Ms = 211.192 kNm

Total Moment = Mc + Ms = 648.725 kNm

Bar size : 25 mm

Number of Bars : 28

Steel Area : 12449.9994 sq.mm

Neutral Axis Depth (Xb): 98.9491 mm

Cc = 1260.254 kN

Mc = 578.213 kNm

Distance between extreme fiberand bar,

db 87.500 mm




14/14

Strain in bar, = 0.0003

Maximum Strain, = 0.0021

as

0.069 kN/mm2

0.0020

as

16.452 kN/mm2

21.552 kN

8.890 kNm

Total Bar Capacity, Cs = -2757.002

kN

Capacity of Column = Cc + Cs =-

1496.748kN

Total Bar Moment, Ms = 563.591 kNm

Total Moment = Mc + Ms = 1141.804 kNm

Check for bi-axial bending, 0.972

Design Moment Mnx= 3.678 kNm

Design Moment Mnz

= 1114832.127 kNm

Total Moment Mox

= 648736.982 kNm

Total Moment Moz

= 1141824.643 kNm

if Mnx or Mnz = 0, then = 1.0

otherwise, = 1.24

Print Calculation Sheet


pedestal 1

Documents