Culvert Design

Samaila Consultant Limited

SAMAILA CONSULTANT LIMITED Consulting Engineers & Planners 1c Collage Road Kaduna

CULVERT No.

CV 9 (2 x 2 Single Box Culvert)

LOCATION

15 + 548

DATE

June.04

DESIGN CODES: 1. BS 8110 : Part 1, 1985 2. BS 5400 : Part 2, 1989

SOIL PARAMETER: Allowable Bearing Capacity

200

kN/m2

25

N/mm2

410

N/mm2

DESIGN DATA: Strength of Concrete, Fcu Strength of Steel,

Fy

Weight of Concrete

gconc

24

kN/m3

Weight of Soil (Filling)

gsoil

18

kN/m3

Weight of Asphalt

gasph

23

kN/m3

1


Ta=100 f= 7200 d=300

2300.=h H=2000 b=300 t=300

2000 B=

300

2300

BS 5400: Part 2 LOADINGS Table 1

gf1 =

1.15

For Self Weight of Culvert

gf2 =

1.50

For Earthfill

gf3 =

1.50

For HA Vehicle

gf4 =

1.30

For HB Vehicle

gf5 =

1.00

For Asphalt

DEAD LOAD 1

For Top Slab

.=

gf1 (d gconc) .=

8.28 kN/m2

2

For Bottom Slab

.=

gf1 (b gconc) .=

8.28 kN/m2

3

For Walls

.=

gf1 (2 t Hgconc) .=

12.74 kN/m2

4

Weight of Fill

.=

5

Weight of Asphalt

.=

gf2 (f gsoil)

.=

194.40 kN/m2

gf5 (Ta gasph) .=

2.30 kN/m2 Total Dead Load =

TOTAL 226.00 kN/m2

226 kN/m2

IMPOSED LOAD BS 5400: Part 2 Clauses 6.2.5 6.2.6 and 6.4.1.5

sHA

1 Stresses due to HA Vehicle,

P=100 kN

2:1

340

7200

2300

2300

Contact Length =

7540mm

sHA =

P/ (Contact Area)

sHA = .=

1.76

2

1.76 kN/m2

kN/m

2


BS 5400: Part 2 Clauses 6.3.1 6.3.2 and 6.3.3

sHB

2 Stresses due to HB Vehicle,

1.8m

6m

1.8m

A 7200

2:1

361

2300

2300 A

P

P 1m

P 1m

P 1m

7200

2300

SECTION A-A Assuming 45 Units HB Vehicle, then the Load Per Axle is 450 kN Contact Width =

7561 mm

Contact Length =

10561 mm

sHB =

BS 5400:

450 / (Contact Area)

sHB =

Part 2 Clause 6.2.7

.=

HB Loading

5.64

>

2

5.64 kN/m2

kN/m

HA Loading

gf4 sHB

Design Load = .=

7.33

Design Load = 7.33 kN/m2

2

kN/m

EARTH PRESSURE ON WALLS BS 5400: Part 2 Clause

f=

5.8.1

Ka =

30

deg

1 - sinf 1 + sinf .=

0.33

3


H2 = 7200 q1 H1 = 9500 2300

q2 2300

At the Bottom of the Culvert q2 = KaH1gsoilgf2 q2 = .=

kN/m2

85.5

85.5 kN/m2

q1 = KaH2gsoilgf2 q1 = .=

64.8

kN/m2

20

kN/m2

64.8 kN/m2

HYDROSTATIC PRESSURE Pw = gw h = SURCHARGE PRESSURE

H1 = 9500

q3

q3 = Ka(Load due to Vehicle + Fill) q3 = .=

kN/m2

67.24

### kN/m2

CHECKING SOIL BEARING CAPACITY 200 kN/m2

Allowable Soil Bearing Capacity = To ta l Loa d on the S oil =

(De ad Lo ad + Impo se d Loa d) .=

233.32

kN/m2

4


ANALYSIS OF FORCES Total Bending Pressure on Members Top Slab =

[ Slab Wt + Fill + Asphalt + HB] =

212.31 kN/m2

Bottom Slab =

[ Top Slab Wt + Base Wt + Walls Wt] =

233.32 kN/m2

Side Walls, q1 =

[ q1 + Surchage Pressure] =

132.04 kN/m2

q2 = [ q2 + Surchage Pressure] =

152.74 kN/m2

212.31 132.04

132.04 A

B

D

C

152.74

152.74 233.32

h=

2.3 m

ts =

0.3 m

L=

2.3 m

tw =

0.3 m

N = [h/L] [ts/tw]3 =

1

N1 = N + 1 =

2

N2 = N + 2 =

3

N3 = N + 3 =

4

N4 = 4N + 9 =

13

N5 = 2N + 3 =

5

N6 = N + 6 =

7

N7 = 2N + 7 =

9

N8 = 3N + 8 =

11

5


Moments due to roof loads

212.31 kN/m2]

[q=

MA = MB = MC = MD = [ -qL2/12N1] =

-46.80kNm

Moments due to weight of walls q = [2G]/[1 + tw] =

22.15 kN/m2

MA = MB = [ +qL2N/12N1N3] =

1.22kNm

MC = MD = [ -N5/N]MA =

-6.10kNm

Moments due to earth pressure

[q=

MA = MB = [ -qh2NN7/60N1N3] = MC = MC = [N8/N7]MA =

85.50 kN/m2] -8.48kNm -10.37kNm

Moments due to surcharge pressure[ q = MA = MB = MC = MD = [ -qh2N/12N1] = Moments due to hydrostatic pressure[ q =

67.24 kN/m2] -14.82kNm 20.00 kN/m2]

MA = MB = q[h2NN7/60N1N3] =

1.98kNm

MC = MD = [N8/N7]MA =

2.42kNm

Moments due to excessive hydrostatic internal pressure[ q = MA = MB = q[h2NN3+L2N5]/[12N1N3] =

9.92kNm

MC = MD = qN[h2N3-L2]/[12N1N3] =

4.35kNm

SUMMATION OF MOMENTS Case 1: culvert empty MA = MB =

-68.88kNm

MC = MD =

-78.09kNm

Case 1: culvert empty MA = MB =

-58.96kNm

MC = MD =

-73.73kNm

6

20 kN/m2]


Moments At The Spans (i) Spans AB 212.31 A

B 68.88

RA =

244.15kN

RB =

244.15kN

x=

2.3

68.88

2.3

78.09

1.15 m

Mmax =

71.51kNm

(Ii) Spans CD 233.32 C

D 78.09

RC =

268.32kN

RD =

268.32kN

x=

1.15 m

Mmax =

76.20kNm

(iii) Spans AD & BC 20.7

9x 132.04

D,C

A,B 73.73

2.3

68.88 y=

RA =

161.89kN

RF =

165.61kN

x=

0.64 m

Mmax =

7.38kNm

(From C)

Bending Moment Diagram 68.88 68.88 71.51 7.38

7.38

76.20 78.09

7

9


DESIGN OF WINGWALLS C 1400 1900 300 300

F C

h/3

300 5700 L=6000

q

Force due to Earth Pressure on the Walls is given by: F = gf [0.5Kagsoil h2] =

23.81kN

This Force is acting at h/3 from the base of the wall Design Moment, M is given by M = F(h/3) = 18.25kNm K=

0.01

As =

215.43

z=

237.5mm

Provide R16 @ 200mm c/c (1005mm2) Base Slabs of Wing Walls The upward Pressure at the base slab is: 7.2 kN/m2

q = (self wt of the slab) = Midspan Moment = ql2/8 = K=

0.02

As =

382.45

32.4kNm z=

237.5mm

Provide R16 @ 200mm c/c (1005mm2) DESIGN OF REINFORCEMENT TOP SLAB REINFORCEMENT Support Moment M, (kNm)

cover = d= Midspan

68.88

71.51

K

0.04

0.05

Z

237.50

237.50

AS

813.03

844.12

R20 @ 200mm (1571mm2)

R20 @ 200mm (1571mm2)

BOTTOM SLAB REINFORCEMENT Support Moment M, (kNm)

Midspan

78.09

76.20

K

0.05

0.05

Z

237.50

237.50

AS

921.74

899.47

R20 @ 200mm (1571mm2)

R20 @ 200mm (1571mm2)

Distribution Bars Area of steel required, As = 0.13%bh =

390 mm2

Provide R16 @ 200mm c/c

8

40 mm 250 mm

Culvert Design

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