8/12/2019 Box_Dsgn_Ca

1/3

Design of Box Culvert

Data

Materials

Concrete Grade M 25

Reinforcing Steel Fe 415

Permissible Stresses

co = 6.25 N/mm2

cbc = 8.33 -do-

st = 200.00 -do-

sc = 170.00 -do-

Design Constants

Ec = 5000 fck = 25000 N/mm2

Es = 200.00 Gpa

m = 10.00

k = m * c / (m *c + st) = 0.2940

j = 1 - k/3 = 0.9020

Q = 1/2 * j * k * c = 1.1045

Clear Cover = 50.00 mm

Main reft. Dia = 20 mm

Design of Raft Slab (Base Slab) :

B M @ Slab-Wall junction = M1 = 145.53 Knm * from STAAD analysis

B M @ Centre = M2 = 82.81 * from STAAD analysis

Eff. Depth required = d = (M/b * Q)= 362.99 mm

Provide overall depth, D = 550.00 mm

Eff. Depth, d = 490.00

Area of Steel reqd =

Outer Face ( Slab-Wall junct),

Ast = M1/(st*j*d) = 1646.34 mm2

Providng Bar dia = 20 mm

Spacing s1 = 191

Provide spacing 150 mm c/c

Inner Face ( Mid Span),

Ast = M2/(st*j*d) = 936.78 mm2

Providng Bar dia = 16 mm

Spacing s1 = 215

Provide spacing 200 mm c/c

Design of Deck Slab (Top Slab) :

8/12/2019 Box_Dsgn_Ca

2/3

B M @ Slab-Wall junction(top) = M1 = 119.09 Knm * from STAAD analysis

B M @ Centre (bott) = M2 = 73.48 * from STAAD analysis

Eff. Depth required = d = (M/b * Q)= 328.36 mm

Provide overall depth, D = 550.00 mm

Eff. Depth, d = 490.00

Area of Steel reqd =

Outer Face ( Slab-Wall junct),

Ast = M1/(st*j*d) = 1347.18 mm2

Providng Bar dia = 20 mm

Spacing s1 = 233 mm c/c

Provide spacing 200 mm c/c

Inner Face ( Mid Span),

Ast = M2/(st*j*d) = 831.23 mm2

Providng Bar dia = 16 mm

Spacing s1 = 242 mm c/c

Provide spacing 200 mm c/c

Design of Vertical Walls : Designed as Compression member with bending

Outer Vertical Wall :

oa ase a r ue o o

Axial Force = P = 182.20 KN * from STAAD analysis

B.M. = M = 43.25 Knm * from STAAD analysis

Adopt Wall thickness = 550 mm

Check for Slenderness ratio :

Eff. Length of Memb (wall) = leff = 4.55 m

Least dimension = 550.00 mmSlenderness ratio = 8.00

8/12/2019 Box_Dsgn_Ca

3/3

Load Case DL + LL + Lat Pr due to (DL + LL + Soil)

Axial Force = P = 346.65 KN * from STAAD analysis

B.M. = M = 9.95 Knm * from STAAD analysis

Adopt Wall thickness = 550 mm

Check for Slenderness ratio :

Eff. Length of Memb (wall) = leff = 4.55 m

Least dimension = 550.00 mmSlenderness ratio = 8.00