Box Culvert Design
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Ac Acc As As min av b c d Fc Ft fcu fs fy G H Hx Hy h KEL L lx ly lz M Mx My Mz q r SLS T t ULS V v vc x x' y' z z'
Area of concrete Area of concrete in compression Area of tension reinforcement Minimum area of tension reinforcement Length of that part of member traversed by shear failure plane With (breath) or effective width of section Cover to outer diameter Effective depth of section Basic force used in defining compressive forces Basic force used in defining tie forces Characteristic strength of concrete Estimated design service stress in the tension reinforcement Characteristic strength of reinforcement Shear modulus Maximum horizontal force Horizontal force in x direction Horizontal force in y direction Overall depth Knife edge load Critical perimeter Dimension of element on x direction Dimension of element on y direction Dimension of element on z direction Design ultimate resistance moment Moment on x axis Moment on y axis Moment on z axis Surcharge load Internal radius of bend Serviceability limit state Traction force Thickness of the element Ultimate limit state Shear force due to design ultimate loads or design ultimate value of a concentrated load Design shear stress Design shear stress in concrete Neutral axis depth Distance from Y axis to the centroid of an element Distance from X axis to the centroid of an element Lever arm Distance from X  Y plane to point where the considered resultant force acting Coefficient, variously defined, as appropriate Strain in tension reinforcement Nominal range of movement Soil friction angle, or diameter Active earth pressure Unit weight of soil Partial load factor Partial load factor
s a
fL f3
D E
DESIGN UNIT
Doc. No. Designed
Date
D EPC DIVISION E CENTRAL ENGINEERING C Reference
CONSULTANCY BUREAU (CECB)
Checked Job Code
Date Page Output
Calculation
D EPC DIVISION E CENTRAL ENGINEERING C Reference
DESIGN UNIT
CONSULTANCY BUREAU (CECB)
Doc. No. Designed Checked Job Code
Date Date Page Output
Calculation
D EPC DIVISION E CENTRAL ENGINEERING C Reference
DESIGN UNIT
CONSULTANCY BUREAU (CECB)
Doc. No. Designed Checked Job Code
Date Date Page Output
Calculation
D EPC DIVISION E CENTRAL ENGINEERING C Reference
DESIGN UNIT
CONSULTANCY BUREAU (CECB)
Doc. No. Designed Checked Job Code
Date Date Page Output
Calculation
D E C
DESIGN UNIT EPC DIVISION CENTRAL ENGINEERING CONSULTANCY BUREAU (CECB)
Doc. No. Designed Checked Job Code
Date Date Page
Reference
Calculation Design of Box CulvertGround LevelX
Output
A
hs
B
H
Y
hw l
h
hw
D
hs
C
Figure 01 Dimentional Properties h l Soil Cover , H Safe Bearing Pressure = = = = = = = = = = = = 1.2 m 1.5 m 7.2 m 150 kN/m2 0.2 m ( hw , h = span/(10 ~15))
Section Thickness Main R/F Cover to R/F Grade of ConcreteProperties of Soil
12 mm 45 mm 25 N/mm2 24 kN/m320 kN/m3
cs
w' 1  Permanent Loads 1.1 Dead Loads
9.81 kN/m325 o
The nominal dead doad consist of the weight of the materials and the part of the structure Structural Engineering Design in preactice (Roger westbrook) (page94) Depth of cover (H) 3 x width = = 3 = 3 x width < = 7.2 m x Unit Weight of Concrete shall be taken as 24 kN/m3 Becouse of the arching of soil, check whether the depth above culvert is > 3 x width of culvert ( in which case limit depth to 3 x width )
1.6So
4.8 m 7.2 m
Depth limited to Surcharge on RoofSurcharge Presure (qr) qr
=
4.8 m
= =
4.8 x 96
20 kN/m2
Soil Engineering (Spangler & Handy)
Casses of conduit installation consider as Ditch Conduit Ditch Conduit A ditch conduit is defined as one which is instaled in a relatively narrowditch dug in passive or undisturbed soil and wich is then covered with earth backfill.
Ceylon Electricity Board
C E B
Dam Safety Environmental &
Doc. No. Designed Checked
S.M.P
Date Date
31.05.2010
C E B
Civil Structure Maintanance
Job Code Calculation
Page
ReferenceMaximum load on ditch condition Depth of cover
1 Output
=
7.2
m
Surcharge on RoofSurcharge Presure (qr) 2 (qr) = Cd..Bd Cd ' = 2.K.' ,
1e2K'(H/Bd)
= tan '
K
=
1sin 1+sin
'

coedicient of friction between fill material and side of ditchActive Lateral earth pressure coeficient
KBd

Horizontal width of ditch at top of conduitUnit weight (wet density) of filling material Height of fill above top of conduite Load coeficient for ditch condition = =

HCd So, K
1sin 1+sin 0.406 0.466 0.76 1.403
Bd =
3.60 m, Consider 1m length of Roof slab
'
= tan ' =
2.K.'.(H/Bd) = Cd (qr) (qr) StructuralEngineering
=
2 = Cd..Bd
=
101.0 kN/m2
1.2 Horizontal Earth Pressure If the backfill properties are known, If wall friction is to be ignored K0 Ka = 1sin ' = ( 1sin ' ) / ( 1+sin ' ) ( = 0 ) = = 0.58 0.41
Design in preactice (Roger westbrook) (page94)
q max
= .Ka.h = 20 x 0.41 x = 73.87 kN/m2 = 20 x 0.41 x = 15.42 kN/m2 = qmax  qep = 58.44 kN/m2
9.1
qep
1.9
q q
Ceylon Electricity Board
C E
Dam Safety
Doc. No. Designed
S.M.P
Date
31.05.2010
C E B
Environmental & Civil Structure Maintanance
Checked Job Code Calculation
Date Page
ReferenceAASHTO 3.7.1 2  Vertical Live Loads
1 Output
For Fill Depths H 8 feet (2400 mm) and Culvert Clear Span Length, The effect of live load is neglected in design when the depth of fill is more than
8 feet3  Hydrostatic Pressure (Internal)
q ip
= C.h = 9.81 x 1.7 = 16.68 kN/m2
4  Analysis Reinforced Concrete Designers Manual (ref5.1) Constant K = h l
{
hs hw
}
3 k1 k3 k5 k7 k8
= = = = = =
1.21 K+1 K+3 2K+3 2K+7 3K+8 = = = = = 2.21 4.21 5.43 9.43 11.64
4.1 Load Case 01 Testing Condition 4.1.1 Hydrostatic Pressure(Internal) Reinforced Concrete Designers Manual (ref5.1)D q = q ip Pressures B.M.D C qip A B
MA =
MB = qip.h2.K.k7 60.k1.k3 = 0.99 kN.m/m MD = Ma. K8 k7 = 1.22 kN.m/m
MC =
4.1.2 Flexure due to weight of wall Wall weight ( G ) = hw..h = Reinforced Concrete Designers Manual (ref5.1)D q1 Pressures B.M.D C G G A B
8.2 kN/m
q1 = 2.G l.hw
=
10.20 kN/m2
MA =
MB = q1.l2.K 12.k1.k3 = 0.22 kN.m/m MD = Ma. K5 K = 0.97
MC =
kN.m/m
4.1.3 Flexure due to weight of Roof q = hs.c = 4.8 kN/m2
Doc. No.
C E B
Dam Safety Environmental & Civil Structure Maintanance
Designed Checked Job Code CalculationA B
S.M.P
Reference
Date 31.05.2010 Date Page 2 Output
MA =D q = q1 Pressures B.M.D C
MB =
MC =
MD
= q.l2 12.k1 = 0.35 Walls 0.22 0.97 0.22 ** 1.53 0.38Walls + Roof 0.14 1.32 1.04 2.35 0.73
kN.m/m f1.4 1.4 1.4 1.4 1.4
Addition of moment for Load case 01 PositionA and B C and D Roof midSpan Base midSpan Walls middle
Hydrostatic 0.99 1.22 0.99 1.22 * 2.06
f 1.4 1.4 1.4 1.4 1.4
ulsMb 1.38 1.70 1.38 1.70 2.88
Roof 0.35 0.35
ulsTotal Mb0.19 1.85 1.45 3.29 1.02 1.19
uls
0.15 2.83 5.00 3.90
**0.82
**0.82 0.35
Table  01 Fixed end mement of the wall for Hydrostatic load MA = = W.L 15 1.61 kN.m/m = = = MC = W.L 10 2.41 kN.m/m W.L 23.3 1.0 kN.m/m
Maximum (ve) moment (Where x is 0.45L from C)
* Calculation of moment at mid span of walls done by aproximatly by adding moment transferred to mid span from FEM to the Maximum negative meoment occurred at 0.45L after moment distribution ** Moment at mid span of the wall is calculated by considering full bending Calculation of midspan moment due to wall load Niutral axis depth from A = 0.26 m
4.2 Load Case 02 Culvert empty and trench filled
Lateral soil pressurees giving rise to flexture in the structure "q"is the rectanguler pressure and "qep" is the triangular pressure4.2.1 Trianguler Pressure,qep Reinforced Concrete Designers Manual (ref5.1)qep Pressures qep D B.M.D C A B
MA =
MB = qep.h2.K.k7 60.k1.k3 = 0.91 kN.m/m MD = MA. K8 k7 = 1.13 kN.m/m
MC =
C E B
Dam Safety Environmental & Civil Structure Maintanance
Doc. No. Designed Checked Job Code Calculation
S.M.P
Reference4.2.2 Surcharge on walls,q Reinforced Concrete Designers Manual (ref5.1)
Date 31.05.2010 Date Page 3 Output
A
B
MB = MC = MD = q.h2.K 12.k1 = 7.72 kN.m/m 4.2.3 Surcharge on Roof ,qr MA = MB = MC = MD = q.l2 12.k1 = 7.45 kN.m/m Addition of moment for Load Case 2Posotion A and B C and D Roof midSpan Base midSpan Walls middle
MA =
D PressuresA
C B.M.DB
D Pressures B.M.D
C
qep0.91 1.13 0.91 1.13
q
Walls & Surcharg Roof(LC1) e (Roof)
Total (Survice) 16.22 17.62 9.70 10.80 6.65
f 1.4 1.4 1.4 1.4 1.4
Total
U.L.S.
7.72 7.72 7.72 7.72
0.14 1.32 1.04 2.35 0.73
7.45 7.45 17.29 17.29 7.45
22.70 24.66 13.58 15.12 9.31
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