footingZ6

Isolated Footing Design(ACI 318-11)

Design For Isolated Footing 1

Isolated Footing 1

Input Values

Footing Geomtery

Footing No. Group ID Foundation Geometry

- - Length Width Thickness

1 1 2.270m 2.270m 0.420m

Footing No. Footing Reinforcement Pedestal Reinforcement

- Bottom Reinforcement(Mz) Bottom Reinforcement(M

x) Top Reinforcement(M

z) Top Reinforcement(M

x) Main Steel Trans Steel

1 #16 @ 230 mm c/c #16 @ 230 mm c/c N/A N/A N/A N/A

Design Type : Calculate Dimension

Footing Thickness (Ft) : 0.250m

Footing Length - X (Fl) : 1.000m

Footing Width - Z (Fw) : 1.000m

Eccentricity along X (Oxd) : 0.000mm

Eccentricity along Z (Ozd) : 0.000mm

Página 1 de 11Isolated Footing Design

24/03/2015file://C:\Staad Foundation Advanced\CalcXsl\footing.xml

Column Dimensions

Pedestal

Design Parameters

Concrete and Rebar Properties

Soil Properties

Sliding and Overturning

Design Calculations

Footing Size

Column Shape : Rectangular

Column Length - X (Dcol

) : 0.350m

Column Width - Z (Bcol

) : 0.350m

Include Pedestal? No

Pedestal Shape : N/A

Pedestal Height (Ph) : N/A

Pedestal Length - X (Pl) : N/A

Pedestal Width - Z (Pw) : N/A

Unit Weight of Concrete : 24.000kN/m3

Strength of Concrete : 21.000MPa

Yield Strength of Steel : 420.000MPa

Minimum Bar Size : #16

Maximum Bar Size : #16

Pedestal Minimum Bar Size : 7

Pedestal Maximum Bar Size : 7

Minimum Bar Spacing : 50.000mm

Maximum Bar Spacing : 450.000mm

Pedestal Clear Cover (P, CL) : 75.000mm

Footing Clear Cover (F, CL) : 75.000mm

Soil Type : Drained

Unit Weight : 0.010kN/m3

Soil Bearing Capacity : 219.200kPa

Soil Bearing Capacity Type: Net Bearing Capacity

Soil Surcharge : 0.000kN/m2

Depth of Soil above Footing : 0.000m

Cohesion : 0.000kN/m2

Coefficient of Friction : 0.500

Factor of Safety Against Sliding : 1.500

Factor of Safety Against Overturning : 1.500

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Initial Length (Lo) = 1.000m

Initial Width (Wo) = 1.000m

Load Combination/s- Service Stress Level

Load

Combination Number

Load Combination Title

Load

Combination Factor

Soil

Bearing Factor

Self

Weight Factor

101 CM+CV 1.00 1.00 0.00

102 2 1.00 1.00 0.00

103 3 1.00 1.00 0.00

104 4 1.00 1.00 0.00

105 5 1.00 1.00 0.00

106 6 1.00 1.00 0.00

107 7 1.00 1.00 0.00

108 8 1.00 1.00 0.00

109 9 1.00 1.00 0.00

110 10 1.00 1.00 0.00

111 11 1.00 1.00 0.00

112 12 1.00 1.00 0.00

113 13 1.00 1.00 0.00

114 14 1.00 1.00 0.00

115 15 1.00 1.00 0.00

116 16 1.00 1.00 0.00

117 17 1.00 1.00 0.00

Load

Combination Number

Load Combination Title

Load

Combination Factor

Soil

Bearing Factor

Self

Weight Factor

118 1U 1.00 1.00 0.00

119 2U 1.00 1.00 0.00

120 3U 1.00 1.00 0.00

121 4U 1.00 1.00 0.00

122 5U 1.00 1.00 0.00

123 6U 1.00 1.00 0.00

124 7U 1.00 1.00 0.00

125 8U 1.00 1.00 0.00

126 9U 1.00 1.00 0.00

127 10U 1.00 1.00 0.00

128 11U 1.00 1.00 0.00

129 12U 1.00 1.00 0.00

130 13U 1.00 1.00 0.00

131 14U 1.00 1.00 0.00

132 15U 1.00 1.00 0.00

133 16U 1.00 1.00 0.00

134 17U 1.00 1.00 0.00

Applied Loads - Service Stress Level

LC Axial

(kN)

Shear X

(kN)

Shear Z

(kN)

Moment X

(kNm)

Moment Z

(kNm)

101 898.740 0.000 0.000 -1.230 -1.140

102 881.381 0.000 0.000 -20.681 61.825

103 876.782 0.000 0.000 -21.689 -64.931

104 887.243 0.000 0.000 19.279 62.691

105 882.644 0.000 0.000 18.271 -64.065

106 872.932 0.000 0.000 -67.655 16.450

107 871.459 0.000 0.000 -68.592 -21.591

108 892.473 0.000 0.000 65.548 19.337

109 891.093 0.000 0.000 65.245 -18.690

110 498.256 0.000 0.000 -26.647 83.291



Final Footing Size

111 492.124 0.000 0.000 -27.991 -85.717

112 506.072 0.000 0.000 26.635 84.446

113 499.940 0.000 0.000 25.291 -84.563

114 486.991 0.000 0.000 -89.278 22.790

115 485.151 0.000 0.000 -89.682 -27.912

116 513.045 0.000 0.000 88.326 26.640

117 511.205 0.000 0.000 87.922 -24.062

Applied Loads - Strength Level

LC Axial

(kN)

Shear X

(kN)

Shear Z

(kN)

Moment X

(kNm)

Moment Z

(kNm)

118 1105.252 0.000 0.000 -1.516 -1.400

119 1063.903 0.000 0.000 -38.554 118.543

120 1055.143 0.000 0.000 -40.474 -122.897

121 1075.069 0.000 0.000 37.562 120.193

122 1066.309 0.000 0.000 35.642 -121.247

123 1047.810 0.000 0.000 -128.028 32.114

124 1045.182 0.000 0.000 -128.604 -40.318

125 1085.030 0.000 0.000 125.692 37.614

126 1082.402 0.000 0.000 125.116 -34.818

127 747.444 0.000 0.000 -38.115 118.941

128 738.684 0.000 0.000 -40.035 -122.499

129 758.610 0.000 0.000 38.001 120.591

130 749.850 0.000 0.000 36.081 -120.849

131 731.351 0.000 0.000 -127.589 32.512

132 728.723 0.000 0.000 -128.165 -39.920

133 768.571 0.000 0.000 126.131 38.012

134 765.943 0.000 0.000 125.555 -34.420

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, Amin

= P / qmax = 4.100m2

Note: Amin

is an initial estimation.

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

max = Respective Factored Bearing Capacity.

Length (L2) = 2.270 m Governing Load Case :

# 101

Width (W2) = 2.270 m Governing Load

Case :

# 101

Depth (D2) = 0.420 m Governing Load

Case :# 125

Depth is governed by Ultimate Load Case

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

Area (A2) = 5.153 m2

Final Soil Height = 0.000 m

Footing Self Weight = 51.939 kN

Gross Soil Bearing Capacity

=

219.20kN/m2

Soil Weight On Top Of 0.000 kN



Pressures at Four Corners

If Au is zero, there is no uplift and no pressure adjustment i s 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

Check for stability against overturning and sliding

Footing =

Load Case

Pressure at corner 1

(q1)

(kN/m2)


(q2)

(kN/m2)


(q3)

(kN/m2)


(q4)

(kN/m2)

Area of footing in uplift (A

u)

(m2)

102 213.3679 149.9408 128.7234 192.1505 0.000

107 193.2298 215.3802 145.0106 122.8602 0.000

109 129.8753 149.0493 215.9855 196.8115 0.000

108 149.4941 129.6558 196.9022 216.7405 0.000

Load Case

Pressure at corner 1 (q

1)

(kN/m2)


2)

(kN/m2)


3)

(kN/m2)


4)

(kN/m2)

102 213.3679 149.9408 128.7234 192.1505

107 193.2298 215.3802 145.0106 122.8602

109 129.8753 149.0493 215.9855 196.8115

108 149.4941 129.6558 196.9022 216.7405

- Factor of safety against sliding Factor of safety

against overturning

Load Case No.

Along X-Direction

Along Z-Direction

Resultant About X-Direction

About Z-Direction

101 0.000 0.000 N/A 829.310 894.782

102 0.000 0.000 N/A 48.369 16.180

103 0.000 0.000 N/A 45.881 15.326

104 0.000 0.000 N/A 52.232 16.063

105 0.000 0.000 N/A 54.828 15.637

106 0.000 0.000 N/A 14.644 60.230

107 0.000 0.000 N/A 14.420 45.810

108 0.000 0.000 N/A 15.453 52.383



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

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

Shear Calculation

Punching Shear Check

109 0.000 0.000 N/A 15.501 54.114

110 0.000 0.000 N/A 21.223 6.790

111 0.000 0.000 N/A 19.955 6.516

112 0.000 0.000 N/A 21.565 6.802

113 0.000 0.000 N/A 22.436 6.710

114 0.000 0.000 N/A 6.191 24.253

115 0.000 0.000 N/A 6.140 19.727

116 0.000 0.000 N/A 6.593 21.858

117 0.000 0.000 N/A 6.599 24.113

Critical Load Case for Sliding along X-Direction : 101

Governing Disturbing Force : 0.000kN

Governing Restoring Force : 449.370kN

Minimum Sliding Ratio for the Critical Load Case : N/A

Critical Load Case for Overturning about X-Direction : 115

Governing Overturning Moment : -89.682kNm

Governing Resisting Moment : 550.637kNm

Minimum Overturning Ratio for the Critical Load Case : 6.140

Critical Load Case for Sliding along Z-Direction : 101




Critical Load Case for Overturning about Z-Direction : 111

Governing Overturning Moment : -85.717kNm

Governing Resisting Moment : 558.550kNm

Minimum Overturning Ratio for the Critical Load Case : 6.516

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

Critical Load Case for Sliding along Resultant

Direction :

101




Compression Development Length Check

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



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

Punching Shear Force, Vu = 1004.019kN, Load Case # 118

One-Way Shear Check

Along X Direction

(Shear Plane Parallel to Global X Axis)

Total Footing Depth, D = 0.420m

Calculated Effective Depth, deff = D - Ccover - 0.5 * db = 0.337m

For rectangular column, = Bcol

/ Dcol

= 1.000

From ACI Cl.11.11.2, bo for column= 2.748m

Equation 11-31, Vc1

= 2114.302kN

Equation 11-32, Vc2

= 2433.345kN

Equation 11-33, Vc3 = 1409.535kN

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

c1, V

c2, V

c3) = 1057.151kN

0.75 X Vc > V

u hence, OK

From ACI Cl.11.2.1.1, Vc = 582.177kN

Distance along X to design for shear,

Dx = 0.623m



Check that 0.75 X Vc > V

ux where V

ux is the shear force for the crit ical load cases at a distance d

eff 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 Vc > V

uz where V

uz i s the shear force for the critical load cases at a distance d

eff 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 above calculations, 0.75 X Vc = 436.633 kN

Critical load case for Vux

is # 125 363.942 kN

0.75 X Vc > V

ux hence, OK

From ACI Cl.11.2.1.1, Vc =

582.177 kN

Distance along X to design for shear, Dz = 0.623 m

From above calculations, 0.75 X Vc = 436.633 kN

Critical load case for Vuz

is # 121 358.314 kN

0.75 X Vc > V

uz hence, OK



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 # 121

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

Bars parallel to X Direction are placed at bottom

Effective Depth deff= 0.337 m

Factor from ACI Cl.10.2.7.3 = 0.850

From ACI Cl. 10.3.2, = 0.02125

From ACI Cl. 10.3.3, = 0.01594

From ACI Cl. 7.12.2, = 0.00180

From Ref. 1, Eq. 3.8.4a, constant m = 23.529

Design for flexure about Z axis is performed at the face of the column

at a distance, Dx = 0.960 m

Ultimate moment, 264.523 kNm

Nominal moment capacity, Mn = 293.915 kNm

(Based on effective depth) Required

= 0.00281

(Based on gross depth) x deff

/ Depth = 0.00225

Since ρmin

≤ ρ≤ ρmax OK

Area of Steel Required, As = 2147.513 mm2

Selected bar Size = #16

Minimum spacing allowed (Smin) = = 50.000mm

Selected spacing (S) = 210.400mm

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 = 187.772mm

Warning:Calculated spacing is more than maximum spacing cosidering cracking condition. Modify spacing

manually if cracking consideration is necessary.

#16 @ 230.000mm o.c.

Required development length for bars = =0.305 m

Available development length for bars, DL

= 0.885 m



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

Critical Load Case # 125

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

Calculate reinforcement ratio for critical load case

Try bar size # 16 Area of one bar = 201.064 mm2

Number of bars required, Nbar = 11

Total reinforcement area, As_total

= Nbar

X (Area of one bar) = 2211.705 mm2

deff

= D - Ccover

- 0.5 X (dia. of one bar) = 0.337 m

Reinforcement ratio, = 0.00289

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

Bars parallel to X Direction are placed at bottom

Effective Depth deff

= 0.321 m

Factor from ACI Cl.10.2.7.3 = 0.850

From ACI Cl. 10.3.2, = 0.02125

From ACI Cl. 10.3.3, = 0.01594

From ACI Cl.7.12.2, = 0.00180

From Ref. 1, Eq. 3.8.4a, constant m = 23.529

Design for flexure about X axis is



Based on spacing reinforcement increment; provided reinforcement is

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

Check to see if width is sufficient to accomodate bars

performed at the face of the column at a distance, Dz = 0.960 m

Ultimate moment, 268.717 kNm

Nominal moment capacity, Mn = 298.575 kNm

(Based on effective depth) Required

= 0.00316

(Based on gross depth) x deff

/ Depth = 0.00241

Since ρmin≤ ρ≤ ρmax OK

Area of Steel Required, As = 2300.073 mm2

Selected Bar Size = #16

Minimum spacing allowed (Smin

) = 50.000mm

Selected spacing (S) = 191.273mm

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 = 187.772mm

Warning:Calculated spacing is more than maximum spacing cosidering cracking condition. Modify spacing

manually if cracking consideration is necessary.

#16 @ 230.000mm o.c.

Required development length for bars = 0.305 m

Available development length for bars, DL

= 0.885 m

Try bar size # 16 Area of one bar = 201.064 mm2

Number of bars required, Nbar = 12

Total reinforcement area, As_total

= Nbar

X (Area of one bar) = 2412.769 mm2

deff

= D - Ccover

- 1.5 X (dia. of one bar)

=

0.321 m

Reinforcement ratio, = 0.00331

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

Print Calculation Sheet



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