Design of Box Culvert(FINAL)

5/21/2018 Design of Box Culvert(FINAL)

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Designed By: Date:

Verified By: Revision:

Version 1

INPUT DATA

CONCRETE COMPRESSIVE STRENGTH, f 'c 28 MPA

REBAR YIELD STRENGTH, fy 420 MPA

CONCRETE UNIT WEIGHT, gc 24 kN/cum

SATURATED SOIL UNIT WEIGHT, gs 18 kN/cum

HEIGHT OFCULVERT, H 4300 mm

WIDTH OF CULVERT, B 6900 mm

THICKNESS OF SIDE WALLS, tw 450 mm

THICKNESS OF TOP SLAB, tts 500 mm

THICKNESS OF BOTTOM SLAB, tbs 600 mm

DEPTH OF FILL, hf 2800 mm

IMPOSED SERVICE DEAD LOADS, wd 3.83 KPa

ALLOWABLE SOIL PRESSURE, Qa 96 KPa

SOIL ANGLE OF FRCITION, 30 Deg.

PREFERRED REBAR SIZE 16 mm

CONCRETE COVER TO REBAR CENTER 75 mmNO. OF REINFORCEMENT LAYERS 2 Shear Status O.K.

MAIN REINFORCEMENT SPACING 150 mm Flexure Status O.K.

TEMPERATURE REINFOR. SPACING 300 mm Soil Pressure Status O.K.

LOADS ON THE CULVERT

For the design purposes a one-meter length of the culvert is considered.

Top Slab

Vehicular Live Loads (HS 20 AASHTO Truck)

Include live loads if hf< 2400mm hf= 2800 mm LL ignored. Design Based on (AASHTO 3.6.1.2

Multiple presence factor 1.20 Traffic travelling parallel to span (AASHTO 3.6.1.1

Width of distributed load (parallel to span) 0 mm (AASHTO 3.6.1.2

Length of distributed load (perpend. to span) 0 mm Equiv. wheel loads don't overlap. (AASHTO 3.6.1.2

Pressure intensity at the specif ied depth of fi ll 0.00 KPa Wheel Load = 72.5 KN

Linear load on the top slab 0.00 KN/m Assumed to act on full width of the slab.

Dynamic Load Allowance (Impact Factor) (AASHTO 3.6.2.2)

IM = 33(1 - 0.00041 hf) > 0% 0.00 % Factor for increasing live load due to impact effects

Increased linear live load 0.00 KN/m Impact and multiple presence factor included.

Weight of earth fill

Linear weight of fill on the slab 50.40 KN/m

Imposed dead loads

Linear imposed dead loads on the slab 3.83 KN/m

Selfweight

Linear selft weight of the slab 12 KN/m

Side Walls

Soil pressure

kah= (1 - sinf) / (1 + sinf) 0.333Surcharge on side walls due to top soil 50.4 KPa

STRUCTURAL DESIGN OF SINGLE CELL BOX CULVERT

Based on AASHTO LRFD Bridge Design 2007 SI

Job Name/Station: Pedestrian Underpass/3391 IDREES/FARHAN NILL

Client: C & W Department IDREES/FARHAN 9-Jul-12

Design Summary


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(cont'd

Height of surcharge (h' = s / gs ) 2.8 m

Linear pressure at the bottom of the side wall 42.6 kN/m

Selfweight

Two side walls = tw(H - tbs - tts) gc 69.1 KN

Bottom Slab

Self weight of the whole structure

Linear soil pressure due to stru. selfweight 90.6474 kN/m See note 1

Vehicular Live Loads (HS 20 AASHTO Truck)

Linear soil pressure due to live loads 0.00 KN/m See note 1

FACTORED LOAD DIAGRAMS

Load factor for dead load 1.25 (AASHTO 3.4.1)

Load factor for horizontal earth pressure 1.50 (AASHTO 3.4.1)

Load factor for live load 1.75 (AASHTO 3.4.1)

82.79 0.00

25.20 25.20

63.9 63.9

113.30924 0.00

ANALYSIS OF THE STRUCTURE

The structure is analyzed using the moment distribution method.

The fixed-end moment at each joint is the superposition of the fixed-end moments due to dead, live and earth pressure loads.

Joint A B D C

Member AC AB BA BD DB DC CD CA

Length 3.20 6.90 6.90 3.20 3.20 6.90 6.90 3.20

Moment of Inertia 0.0375 0.0417 0.0417 0.0375 0.0375 0.0500 0.0500 0.0375

Distrib. Factor 0.66 0.34 0.34 0.66 0.62 0.38 0.38 0.62

FEM 34.71 -328.46 328.46 -34.71 41.32 -449.55 449.55 -41.32

Distribution 193.85 99.89 -99.89 -193.85 252.25 155.98 -155.98 -252.25

Carry Over -126.13 -49.95 49.95 126.13 -96.93 -77.99 77.99 96.93

Distribution 116.20 59.88 -59.88 -116.20 108.08 66.83 -66.83 -108.08

Carry Over -54.04 -29.94 29.94 54.04 -58.10 -33.42 33.42 58.10

Distribution 55.42 28.56 -28.56 -55.42 56.55 34.97 -34.97 -56.55Carry Over -28.27 -14.28 14.28 28.27 -27.71 -17.48 17.48 27.71

Distribution 28.08 14.47 -14.47 -28.08 27.93 17.27 -17.27 -27.93

Carry Over -13.96 -7.24 7.24 13.96 -14.04 -8.63 8.63 14.04

Distribution 13.99 7.21 -7.21 -13.99 14.01 8.66 -8.66 -14.01

Carry Over -7.01 -3.60 3.60 7.01 -6.99 -4.33 4.33 6.99

Distribution 7.00 3.61 -3.61 -7.00 7.00 4.33 -4.33 -7.00

Carry Over -3.50 -1.80 1.80 3.50 -3.50 -2.16 2.16 3.50

Distribution 3.50 1.80 -1.80 -3.50 3.50 2.16 -2.16 -3.50

Moment Sum 219.85 -219.85 219.85 -219.85 303.37 -303.37 303.37 -303.37


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SHEAR MOMENT DIAGRAMS

Top Slab

Mmax (+) 272.84 kN/m

Mmax (-) -219.85 kN/m

Design Moment 272.84 kN/m

Vmax (+) 285.62 kN

Vmax (-) -257.06 kN

Design Shear 213.18 kN

At distance d from the face of the support

Bot tom Slab

Mmax (+) 303.37 kN/m

Mmax (-) -370.96 kN/m


Vmax (+) 390.92 kN

Vmax (-) -390.92 kN



-300.0

-200.0

-100.0

0.0

100.0

200.0

300.0

0.

00

1.

04

2.

07

3.

11

4.

14

Moment(kN

-m)

Distance x (m)

Top Slab Moment Diagram

-400.0

-300.0

-200.0

-100.0

0.0

100.0

200.0

300.0

400.0

0.

00

1.

04

2.

07

3.

11

4.

14

Shear(kN)

Distance x (m)

Top Slab Shear Diagram

-500.0

-400.0

-300.0

-200.0

-100.0

0.0

100.0

200.0

300.0

400.0

0.

00

1.

04

2.

07

3.

11

4.

14

Moment(kN-m)

Distance x (m)

Bottom Slab Moment Diagram

-500.0

-400.0

-300.0

-200.0

-100.0

0.0

100.0

200.0

300.0

400.0

500.0

0.

00

1.

04

2.

07

3.

11

4.

14

Shear(kN)

Bottom Slab Shear Diagram


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500.0

Side Walls

Mmax (+) 303.37 kN/m

Mmax (-) -176.84 kN/m


Vmax (+) -81.91 kN

Vmax (-) -184.15 kN



THICKNESS CHECK

Shear strength provided by concrete = fVc= f0.17 (f'c)0.5

bwd

Component d (mm) fVc kN) Vd (kN) StatusTop slab 425 286.7 213.2 O.K.

Bottom slab 525 354.2 280.4 O.K.

Side walls 375 253.0 168.5 O.K.

REINF. CALCULATIONS

Minimum reinforcement ratio for main reinforcement, min 0.0006 See note 2

Minimum reinforcement ratio for temperature reinforcement, min 0.0008 See note 2

Maximum center to center spacing of reinforcement, smax 900 mm Max (1.5 t, 450)

d (mm) Mu(kN-m) As (mm2) As prov act min Status act min

Top slab 425 303.2 1887 2681 0.0054 0.0012 O.K. 0.0054 0.0017

Bottom slab 525 412.2 2077 2681 0.0045 0.0012 O.K. 0.0045 0.0017

Side walls 375 337.1 2378 2681 0.0060 0.0012 O.K. 0.0060 0.0017

SOIL PRESSURE CHECK

Pressure on soil 90.65 KPa

Allowable soil pressure 96.00 KPa

Status O.K.

1- In reality, the uplift soil pressure on the bottom slab may not be uniform. However, for simplicity, it shall be assumed to be uniform.

2- Minimum reinforcement ratio found is for one layer of reinforcement and shall be multiplyed by 2 if there is 2 layers of reinforcement

TEMPRATURE RComponent

MAIN REINFORCEMENT

-300.0

-200.0

-100.0

0.0

100.0

200.0

300.0

400.0

0.

00

0.

48

0.

96

1.

44

1.

92

2.

40

Moment(kN

-m)

Distance x (m)

Side Walls Moment Diagram

-200.0

-180.0

-160.0

-140.0

-120.0

-100.0

-80.0

-60.0

-40.0

-20.0

0.0

0.

00

0.

48

0.

96

1.

44

1.

92

2.

40

Shear(kN)

Distance x (m)

Side Walls Shear Diagram


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2 Minimum reinforcement ratio found is for one layer of reinforcement and shall be multiplyed by 2 if there is 2 layers of reinforcement.

this design spreadsheet can not be used since it is possible that two axle loads come on the culvert.


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Design of Box Culvert(FINAL)

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