Box Cul1 (Autosaved)

RCC BOX CULVERT,DESIGNATION: [ 1/3 X 3/0] 1. SALIENT SALIENT FEATURES FEATURES Clear Span Clear height Top Slab thickness Bottom slab thickness Side wall thickness

65mm (w.c)

a b d e f

3 3 0.42 0.42 0.42

m m m m m

d=420

3

γc

24 kN/m

γw.c

24 kN/m3

Unit weight of earth

γe

18 kN/m3

Unit weight of water Co-eff. of EP at rest Total cushion on top Thick. of wearing coat Carriageway

10 kN/m3 Ca 0.5 0 m 0 .0 6 5 m 8 L divided

Concrete grade

f ck

25 Mpa

Steel grade

f y

415 415 Mpa

C/Stress of concrete

σsc

8.33 8.33 Mpa Mpa

C/Stress of steel

σst

200 200 Mpa

Modular ratio Neutral axis) Effective depth) Moment of resistance)

m n j k

10 0 .2 9 4 0 .9 0 2 1.105 Mpa

Unit weight of concrete Unit weight of w.coat

 b=3000 a=3000

f=420

γw

420

e=420

Fig.-1 CROSS-SECTION OF BOX (All dimensions are in mm)

2. LOAD CALCULA CALCULATION TION 2.1 Top Slab 2.1.1 Dead Load  a) Wt. of wearing course

=

1.43 kN/m2

b) Se S elf Wt. of top-slab

=

10.08 kN/m2

c) Total

=

12.08 kN/m2

2.1.2

( Adopt min. of 2.00 kN/m2 as per MOST specif.)

Live Load 

Consiering IRC Class 70R(Tracked)loading, the load load dispersal & position is shown below: 840 350 kN

1220

4570

840 350 kN

4700 970

970

3840 a) In Longitudinal direction

 b) In Transverse direction direction

Fig.-2 Dispersal under Class 70R (T) one Track (All dimensions are in mm)

Dispersal perpendicular to span: Dispersal in span direction:

=w+2t =4.57+2t+2d

=0.84+2x0.065 =4.57+2x0.066

0.97 m 4.70 m

Note: 1) For load dispersal refer IRC:21-2000 clause 305.16.3, where in addition to the dimension of tyre contact area over the wearing surface, twice the overall depth of the slab including the the wearing course thickness is consiered. In the above case, since the length of the wheel is more than the total width of box at top i.e., 3.84m furthur dispersal by "2d" is not possible, hence not taken. In case where the length of  load is less than the width of box but works out more when "2d" is added, the dispersal length shall be restricted to top width of box. 2)

As the load of the wheel after dispersal in transverse direction does not over lap, both the wheels need to be taken separately.

3) This shallbe the load when α is zero and live load is taken to disperse through wearing coat only. Load per unit area of top-slab: Impact factor Load including impact factor : 2.1.3 Total Load (DL +LL)

=350/(4.70 X 0.97) =25% = 76.77 x 1.25 =12.08+95.96

2.2 Bottom Slab: 2.2.1 Dead Load  Load from top salb

=

Load of walls

=

Total

12.08 kN/m2 (2 x 0.42 x 3.00 x 24)/3.84

=

15.75 kN/m2

=

27.83 kN/m2

2.2.1 Live Load i) Dispersed area when 1 track loading is considered Load per unit area when 1 track load (covering 2-lanes) is considered

76.77 kN/m2 [as per clause 211.3 a) i) of IRC:6-2000] 95.96 kN/m2 108.04 kN/m2