Descripción: Project on the design of a concrete box culvert, contains introduction, methodology and lit review
Project on the design of a concrete box culvert, contains introduction, methodology and lit reviewDescription complète
Project on the design of a concrete box culvert, contains introduction, methodology and lit review
Full description
BOX CULVERT DESIGN
Calculation for 1.4m x 1.5m RCC box culvert :
Size of Culvert Span of culvert
=
1.4 10
m m
x
1.5
m
Culverts will be designed for Class “A” loading as per IRC standards for road with 10 m width and above.
` Super imposed load(assuming 2 tyres) Grade of Concrete Grade of Steel SBC at 1.5m depth Density of Soil Angle of Repose (Ø) Unit weight of concrete
= = = = = = = =
6.8 3.4
Assumed thickness of slab as
=
Weight of top slab (W1) Super imposed load (W2)
= =
3.75 kN/m2 4.39 kN/m2
Total weight on top slab (W)
=
8.14 kN kN/m2
M Fe 20 18 30 25
t t 25 415 t/m2 kN/m3 deg kN/m3
150 mm
Weight of two vertical walls (W3) = 12.375 kN/m Surcharge = 20 KN/m2 Considering one metre run of culvert, Pressure intensity on the base slab =
{[(W * h) + W3] / h}
=
15.64 kN kN/m2
Loading diagram
0 0 5 1
1400mm
Weight of bottom slab will be directly counteracted by the corresponding ground reaction. At any depth (h) from top slab, lateral pressure intensity (p) {W1 x [1-sin Ø/1+sin Ø)] + 18000 h{1-sin Ø/1+sin Ø)]}
p
=
At level at top slab (h) p
= =
0m 14.39 kN/m2
At level at bottom (h) p
= =
1.9 m 48.59 kN/m2
Considering one metre run of the culvert and each member as a separate fixed member, Fixed end moments are: ANALYSIS AND DESIGN METHODOLOGY:
The RCC box culvert will be designed as per the guidance provided in the civil technical specification. Earth pressure for all under ground water storage structure shall be taken as at rest. In addition to earth pressure the vehicular traffic load as per the IRC specification of Class "A" shall be taken into account. Manual load calculations are made and analysed using the software STAAD pro for the loadings, bending moments and shear forces and design/detail shall be made as per the manual calculation Bending Moments
Considering maximum misspan section of slab for bending moment (M) = 7.532kNm For top slab;
Assuming the depth of slab as 150mm with effective cover of 25mm., Depth available = 150-25 = 125 mm Mu = 7.532 x 1.5 = 11.298 kNm Mu,lim = b x d^2 x Q = 1000 x 125^2 x 3.45 = 53.906 kNm < Percentage reinforcement (Pt) = Mu/bd^2 = 11.3 x 10^6/1000 x 125^2 = 0.589248 Percentage tension reinforcement (pt) from SP16 Pt = 0.17% Considering Minimum area of reinforcement 0.12% Therefore area of reinforcement = (Gross area of slab x 0.12)/100 = (1000 x 150 x 0.12)/100 = 180 mm2 Area of reinforcement with Pt = 0.17% = (1000 x 125 x 0.17)/100 = 212.5 mm2
11.3 kNm Hence depth is OK
Providing 12mm Ø bars, Spacing
Providing dist. bar as 10mm Ø bars, Spacing
= =
(113.04 X 1000)/212.5 531.95 mm
Say 200 mm c/c spacing
=(78.5 X 1000)/180 436.11
Say 150 mm c/c spacing
For bottom slab and side walls;
Assuming the depth of slab as 150mm with effective cover of 25mm., Depth available = 150-25 = 125 mm Mu = 8.213 x 1.5 = 12.32 kNm Mu,lim = b x d^2 x Q = 1000 x 125^2 x 3.45 = 53.906 kNm <
12.3 kNm Hence depth is OK
Percentage reinforcement (Pt) = Mu/bd^2 = 12.32 x 10^6/1000 x 125^2 = 0.78848 Percentage tension reinforcement (pt) from SP16 Pt = 0.229% Considering Minimum area of reinforcement 0.2% Therefore area of reinforcement = (Gross area of slab x 0.2)/100 = (1000 x 150 x 0.2)/100 = 300 mm2 Area of reinforcement with Pt = 0.229% = (1000 x 125 x 0.229)/100 286.25 mm2 Providing 12mm Ø bars, Spacing = (113.04 X 1000)/300 = Providing dist. bar as 10mm Ø bars, Spacing
