Culvert Design
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Transcript of Culvert Design
Samaila Consultant Limited
1
SAMAILA CONSULTANT LIMITEDConsulting Engineers & Planners1c Collage RoadKaduna
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
DESIGN DATA:
Strength of Concrete, Fcu 25
Strength of Steel, Fy 410
Weight of Concrete 24
Weight of Soil (Filling) 18
Weight of Asphalt 23
kN/m2
N/mm2
N/mm2
gconc kN/m3
gsoil kN/m3
gasph kN/m3
Samaila Consultant Limited
2
Ta= 100
f= 7200
d= 300
2300 .=hH= 2000
b= 300
t= 300 2000 300
B= 2300
BS 5400:Part 2 LOADINGSTable 1
1.15 For Self Weight of Culvert
1.50 For Earthfill
1.50 For HA Vehicle
1.30 For HB Vehicle
1.00 For Asphalt
DEAD LOAD
1 For Top Slab .= .= 8.28
2 For Bottom Slab .= .= 8.28
3 For Walls .= .= 12.74
4 Weight of Fill .= .= 194.40
5 Weight of Asphalt .= .= 2.30Total Dead Load =
TOTAL 226.00 226
IMPOSED LOAD
BS 5400: 1 Stresses due to HA Vehicle, Part 2 P=100 kNClauses6.2.56.2.6and 2:1 340 72006.4.1.5
2300
2300
Contact Length = 7540 mm
P/ (Contact Area)
.= 1.7589654469 1.76
gf1 =
gf2 =
gf3 =
gf4 =
gf5 =
gf1 (d gconc) kN/m2
gf1 (b gconc) kN/m2
gf1 (2 t Hgconc) kN/m2
gf2 (f gsoil) kN/m2
gf5 (Ta gasph) kN/m2
kN/m2 kN/m2
sHA
sHA =
sHA =
kN/m2 kN/m2
Samaila Consultant Limited
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BS 5400: 2 Stresses due to HB Vehicle, Part 2Clauses6.3.16.3.2 1.8m 6m 1.8mand6.3.3 A
7200 2:1 361
2300
2300
A
P P P P1m 1m 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
BS 5400: 450 / (Contact Area)
Part 2
Clause .= 5.6354452273 5.646.2.7
HB Loading > HA Loading
Design Load =Design Load =
.= 7.3260787955 7.33
EARTH PRESSURE ON WALLSBS 5400:
Part 2 f = 30 degClause
5.8.1
.= 0.33333333
sHB
sHB =
sHB =
kN/m2 kN/m2
gf4 sHB
kN/m2 kN/m2
Ka = 1 - sinf
1 + sinf
Samaila Consultant Limited
4
H2 =7200
H1 =9500
2300
2300
At the Bottom of the Culvert
q2 =
.= 85.5 85.5
q1 =
.= 64.8 64.8
HYDROSTATIC PRESSURE
20
SURCHARGE PRESSURE
H1 =9500
q3
Ka(Load due to Vehicle + Fill)q3 =
.= 67.2420263 67.2
CHECKING SOIL BEARING CAPACITY
Allowable Soil Bearing Capacity = 200
Total Load on the Soil = (Dead Load + Imposed Load)
.= 233.32454033
q1
q2
q2 = KaH1gsoilgf2
kN/m2 kN/m2
q1 = KaH2gsoilgf2
kN/m2 kN/m2
Pw = gw h = kN/m2
q3 =
kN/m2 kN/m2
kN/m2
kN/m2
Samaila Consultant Limited
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ANALYSIS OF FORCESTotal Bending Pressure on Members
Top Slab = [ Slab Wt + Fill + Asphalt + HB] = 212.31
Bottom Slab = [ Top Slab Wt + Base Wt + Walls Wt] = 233.32
132
152.74
212.306
132 132A B
D C152.7 152.74
233.325
h = 2.3 m 0.3 m
L = 2.3 m 0.3 m
1
2
3
4
13
5
7
9
11
kN/m2
kN/m2
Side Walls, q1 = [ q1 + Surchage Pressure] = kN/m2
q2 = [ q2 + Surchage Pressure] = kN/m2
ts =
tw =
N = [h/L] [ts/tw]3 =
N1 = N + 1 =
N2 = N + 2 =
N3 = N + 3 =
N4 = 4N + 9 =
N5 = 2N + 3 =
N6 = N + 6 =
N7 = 2N + 7 =
N8 = 3N + 8 =
Samaila Consultant Limited
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212.31
-46.80 kNm
Moments due to weight of walls
22.15
1.22 kNm
-6.10 kNm
85.50
-8.48 kNm
-10.37 kNm
67.24
-14.82 kNm
20.00
1.98 kNm
2.42 kNm
20
9.92 kNm
4.35 kNm
SUMMATION OF MOMENTS
Case 1: culvert empty
-68.88 kNm
-78.09 kNm
Case 1: culvert empty
-58.96 kNm
-73.73 kNm
Moments due to roof loads [ q = kN/m2]
MA = MB = MC = MD = [ -qL2/12N1] =
q = [2G]/[1 + tw] = kN/m2
MA = MB = [ +qL2N/12N1N3] =
MC = MD = [ -N5/N]MA =
Moments due to earth pressure [ q = kN/m2]
MA = MB = [ -qh2NN7/60N1N3] =
MC = MC = [N8/N7]MA =
Moments due to surcharge pressure[ q = kN/m2]
MA = MB = MC = MD = [ -qh2N/12N1] =
Moments due to hydrostatic pressure[ q = kN/m2]
MA = MB = q[h2NN7/60N1N3] =
MC = MD = [N8/N7]MA =
Moments due to excessive hydrostatic internal pressure[ q = kN/m2]
MA = MB = q[h2NN3+L2N5]/[12N1N3] =
MC = MD = qN[h2N3-L2]/[12N1N3] =
MA = MB =
MC = MD =
MA = MB =
MC = MD =
Samaila Consultant Limited
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Moments At The Spans
(i) Spans AB 212.31
A B68.8768235 2.3 68.877
244.15 kN
244.15 kN
x = 1.15 m
71.51 kNm
(Ii) Spans CD233.32
C D78.0860014 2.3 78.086
268.32 kN
268.32 kN
x = 1.15 m
76.20 kNm
(iii) Spans AD & BC
20.7 9 x132.042
D,C A,B73.73 2.3 68.877
y = 9
161.89 kN
165.61 kN
x = 0.64 m (From C)
7.38 kNm
Bending Moment Diagram
68.8768
68.88
71.51
7.38 7.38
76.2078.09
RA =
RB =
Mmax =
RC =
RD =
Mmax =
RA =
RF =
Mmax =
Samaila Consultant Limited
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DESIGN OF WINGWALLS
C1400
1900 F300300 C h/3
300 5700L= 6000 q
Force due to Earth Pressure on the Walls is given by:
23.805 kN
This Force is acting at h/3 from the base of the wall
Design Moment, M is given by M = F(h/3) =
18.2505 kNm
K = 0.01 z = 237.5 mm
215.43
Base Slabs of Wing Walls
The upward Pressure at the base slab is:
q = (self wt of the slab) = 7.2
32.4 kNm
K = 0.020736 z = 237.5 mm
As = 382.453189
DESIGN OF REINFORCEMENT cover = 40 mmd = 250 mm
TOP SLAB REINFORCEMENTSupport Midspan
Moment M, (kNm) 68.88 71.51
K 0.04 0.05
Z 237.50 237.50
813.03 844.12
R20 @ 200mm R20 @ 200mm
BOTTOM SLAB REINFORCEMENT
Support Midspan
Moment M, (kNm) 78.09 76.20
K 0.05 0.05
Z 237.50 237.50
921.74 899.47
R20 @ 200mm R20 @ 200mm
Distribution Bars
390
Provide R16 @ 200mm c/c
F = gf[0.5Kagsoil h2] =
As =
Provide R16 @ 200mm c/c (1005mm2)
kN/m2
Midspan Moment = ql2/8 =
Provide R16 @ 200mm c/c (1005mm2)
AS
(1571mm2) (1571mm2)
AS
(1571mm2) (1571mm2)
Area of steel required, As = 0.13%bh = mm2