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8/11/2019 Design of Two Cell Box Structure
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DESIGN DATA:
27.160 m
22.050 m
20.550 m
25.485 m
12.000 m
11.000 m0.400 m
0.400 m
0.400 m
0.300 m
0.056 m
8.000 + 0.350 = 8.350 m
8.000 + 0.350 = 8.350 m
5.754 + 0.400 = 6.154 m
0.500 m
1.250 x 0.250 m
1.250 x 0.250 m
1.675 m
2.400 t / m
1.000 t / m
M 35
1190 t / m
20400 t / m
m - 10
0.368
0.877
192 t / m
Top slab = 16.70 x 0.40 x 2.40 = 16.032 t / m
bottom slab = 16.70 x 0.40 x 2.40 = 16.032 t / m
End Webs = 2 x 6.154 x 0.40 x 2.40 = 11.816 t / m
Central Web = 1 x 6.154 x 0.30 x 2.40 = 4.431 t / m
Haunches ( 16 nos.) = 16 x 0.125 x 1.25 x 2.40 = 6.000 t / m
54.311 t / m
( 54.311 / 16.700 ) = 3.252 t / m
Say, 3.300 t / m
Wearing Coat (@ 0.20 t / sqm.) = 0.200 t / m
2 x ( 0.700 / 12.000 ) = 0.117 t / m
Total = ( 0.200 + 0.117 ) =
0.317 t / m
DRY CONDITION
Due to DL of Box and SIDL = ( 3.300 + 0.317 ) = 3.617 t / m
Due to LL-70R Wheeled Load = 100 / ( 12 x 16.70 ) = 0.499 t / m
Due to Earth inside the Box = 1.10 x 2.00 = 2.200 t / m
Total Base Pressure = ( 3.617 + 0.499 + 2.200 ) = 6.316 t / m
Eff. horizontal span end cell(upto c/l of web) =
CALCULATION OF LOADS AND CORRESPONDING BASE PRESSURE:
Total Weight =
SUPERIMPOSED DEAD LOAD ( Per metre width ):
Formation Level along c/l of carriageway (m) =
Bed Level (m) =
Founding Level (m) =
Heighest Flood Level (m) =
Overall width of bridge =
width of carriageway =Thickness of top slab =
Thickness of bottom slab =
Thickness of Web =
Thickness of Central Web =
Tkickness of wearing coat =
Modular ratio,
Eff. horizontal span inner cell(upto c/l of web) =
Eff. vertical span (upto c/l of slab) =
width of crash barrier =
Size of haunches in outer webs -
Size of haunches in inner web -
Depth of water at HFL. from formation lvl =
Unit wt of concrete =
Submerged density of earth =
Grade of Concrete -
Permissible Compressive stress in Concrete -
Permissible Tensile stress in Steel -
Equivalent upward Base pressure =
DEAD LOAD-( Per metre width ):
Equivalent upward Base pressure =
0.317 t / m
CHECK FOR BASE PRESSURE
Crash Barrier ( @ 0.70 t/m on each side ) =
k -
Lever arm factor, j -
Moment of Resistance, Q -
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HFL CONDITION
Due to DL of Box, SIDL & LL = ( 3.617 + 0.499 ) = 4.116 t / m
Due to Water inside the Box = ( 4.423 x 1.000 ) = 4.423 t / m
Buoyancy = ( 4.823 x - 1.000 ) = - 4.823 t / m
Total Base Pressure = ( 4.116 + 4.423 - 4.823 ) = 3.716 t / m
EARTH PRESSURE
CASE - 1
Dry Density of Soil = 2.000 t / m
0.5
CASE - 2
Dry Density of Soil = 1.800 t / m
0.3
Cooefficient of Earth Pressure at rest =
Cooefficient of Earth Pressure at rest =
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Height (m)Location of Earth
PressureCase - 1
Surcharge for
1.2 mCase - 2
Surcharge for
1.2 m
0.256 C/l of top slab 0.256 1.2 0.138 0.648
1.956 Face of top haunch 1.956 1.2 1.056 0.648
3.333 Mid. of web 3.333 1.2 1.8 0.648
4.71 Face of bot. haunch 4.71 1.2 2.543 0.648
6.41 C/l bottom slab 6.41 1.2 3.461 0.648
Height (m)Location of Earth
PressureCase - 1
Surcharge for
1.2 mCase - 2
Surcharge for
1.2 m
0.256 C/l of top slab 0.256 1.2 0.138 0.648
1.675 H.F.L. Level 1.675 1.2 0.905 0.648
1.956 Face of top haunch 1.956 1.2 1.056 0.648
3.333 Mid. of web 3.333 1.2 1.8 0.648
4.71 Face of bot. haunch 4.022 1.2 2.488 0.648
6.41 C/l bottom slab 4.872 1.2 3.338 0.648
For Dry Condition
H.F.L. Condition
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9.9 0.7
2 1
3
100 mm
100 mm
6
4 5
5.8 0.8
S No. t b t F (force) Acting atEccentricity
e
1 0.7 1.0 0.08 2.04 0.04 m from top 0.16
2 9.9 / 2 1.0 0.08 14.41 0.027 m from top 0.173
3 0.7 / 2 1.0 0.1 1.27 0.113 m from top 0.087
4 5.8 / 2 1.0 0.08 8.44 0.027 m from bottom -0.173
5 0.8 1.0 0.08 2.33 0.04 m from bottom -0.16
6 0.8 / 2 1.0 0.1 1.46 0.113 m from bottom -0.087
F = 29.95 F.e = 0.97
2
t2
Hence, t = 0.8 C
0.1
M = [ F x e ] = Ec x x t x A x e
0.97 = 36.387 x x 0.0667
0.08
0.08
0.1
0.08
0.08
EFFECT OF TEMPERATURE FALL
80 mm
80 mm
A = b x t
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Where
L0=
a =
=b / L0= 12 / 8 = 1.5
2.48
b1=
0.5 1.62 2.06 7.32 0.5
11
0.5 1.63 1.93 7.44 0.5
11
2.48
Live Load a (m) b1(m) beff(m) beff/2 (m)Max.
available
Width (m)
Load
Intensity
70 3.712 0.952 6.065 3.033 7.213 9.705
70 3.664 0.952 6.051 3.026 7.206 9.715
70 3.362 0.952 5.933 2.966 7.146 9.795
70 3.736 0.952 6.072 3.036 7.216 9.701
63.7 2.08 0.952 4.825 2.413 6.593 9.665
70 4.012 0.952 6.121 3.061 7.241 9.668
70 2.285 0.952 5.068 2.534 6.714 10.426
For Max. BM (Sagging) in Midspan
For Max. BM (Sagging) at end of haunch 1
Effective width =beff. .a.[ 1 - a / L0] + b 1
Hence as per cl. 305.16.2 of IRC:21, =
breath of loads over the deck slab after 45 dispersion through wearing coat
the effective span
A constant depending upon the ratio b/l0, where b is the width of the slab
the distance of centre of gravity of the concn load from the nearer
= 0.84 + 2 x 0.056 = 0.952 m (for 70R tracked)
= 0.81 + 2 x 0.056 = 0.922 m (for 70R wheeled)
TRANSVERSE POSITION OF LIVE LOAD ( CLASS 70R TRACKED)
TRANSVERSE POSITION OF LIVE LOAD ( CLASS 70R WHEELED)
CALCULATION OF EFFECTIVE WIDTH AND LOAD INTENSITY =
For Max. BM (Hogging) at End web
Class 70R Tracked Load
For Max. BM (Hogging) in Midspan
For Max. BM (Hogging) at start of haunch 2
For Max. BM (Hogging) at middle web
For Max. BM (Hogging) at end of haunch 9
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17.0 1.31 0.92 3.661 1.831 5.591 3.041
17.0 2.68 0.92 5.435 2.718 6.778 2.508
17.0 2.62 0.92 5.381 2.69 6.75 2.518
17.0 1.25 0.92 3.558 1.779 5.488 30.098
17.0 1.45 0.92 3.894 1.947 5.824 2.919
17.0 2.82 0.92 5.554 2.777 6.837 2.487
17.0 2.48 0.92 5.246 2.623 6.683 2.544
17.0 1.11 0.92 3.309 1.654 5.239 3.245
17.0 3.9 0.92 6.077 3.038 7.098 2.395
17.0 3.08 0.92 5.743 2.871 6.931 2.453
17.0 0.03 0.92 0.996 0.498 1.992 8.533
17.0 1.34 0.92 3.712 1.856 5.642 3.013
12.0 3.47 0.92 5.951 2.976 7.036 1.706
12.0 3.36 0.92 5.902 2.951 7.011 1.712
12.0 1.86 0.92 4.507 2.254 6.314 1.901
12.0 3.38 0.92 5.911 2.956 7.016 1.71
17.0 2.84 0.92 5.57 2.785 6.845 2.484
17.0 1.47 0.92 3.926 1.963 5.856 2.903
17.0 1.58 0.92 4.099 2.049 6.029 2.82
17.0 2.95 0.92 5.653 2.827 6.887 2.469
17.0 1.75 0.92 4.313 2.156 6.216 2.735
17.0 3.12 0.92 5.642 2.821 6.881 2.471
17.0 2.18 0.92 4.855 2.428 6.488 2.62
17.0 0.81 0.92 2.736 1.368 4.666 3.643
17.0 2.52 0.92 5.203 2.601 6.661 2.552
17.0 3.89 0.92 5.878 2.939 6.999 2.429
12.0 2.33 0.92 5.017 2.509 6.569 1.827
12.0 0.81 0.92 2.736 1.368 4.666 2.572
8.0 3.15 0.92 5.787 2.893 6.953 1.515
17.0 1.63 0.92 4.175 2.088 6.105 2.784
17.0 3 0.92 5.689 2.844 6.904 2.462
For Max. BM (Sagging) at end of haunch 1
Class 70R Wheeled Load
For Max. BM (Hogging) at End web
For Max. BM (Sagging) in Midspan
For Max. BM (Hogging) at end of haunch 9
For Max. BM (Hogging) at start of haunch 2
For Max. BM (Hogging) at middle web
For Max. BM (Hogging) in Midspan
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9.715 /
Corresponding base pressure =
For Max BM (Sagging) at end of haunch 1
Dispersion width =
Live load intensity as udl =
Corresponding base pressure =
Corresponding base pressure =
Corresponding base pressure =
Corresponding base pressure =
Corresponding base pressure =
Corresponding base pressure =
Live load intensity as udl =
For Max BM (Sagging) at midspan
Dispersion width =
Live load intensity as udl =
For Max BM (hogging) at middle web
Dispersion width =
Live load intensity as udl =
For Max BM (Sagging) at end of haunch 9
Dispersion width =
Live load intensity as udl =
For Max BM (Hogging) at start of haunch 2
Dispersion width =
Live load intensity as udl =
Live load intensity as udl =
For Max BM (Hogging) in Mid span
Dispersion width =
LOAD INTENSITY AND CORRESPONDING BASE PRESSURE FOR CLASS 70R TRACKED:
Dispersion width = Track length over the span after 45odispersion through wearing coat and slab
For Max BM (Hogging) at End web
Dispersion width =
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( 0.263 + 0.456 ) = 0.719 m
( 0.263 + 0.912 ) = 1.175 m
( 3.041 / 1.175 ) = 2.588 t / m
( 2.508 / 1.175 ) = 2.134 t / m
( 2.518 / 1.175 ) = 2.143 t / m
( 3.098 / 1.175 ) = 2.637 t / m
0.669 t / m
( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.456 ) = 0.719 m
( 2.919 / 1.175 ) = 2.484 t / m
( 2.487 / 1.175 ) = 2.117 t / m
( 2.544 / 1.175 ) = 2.165 t / m
( 3.245 / 1.175 ) = 2.762 t / m
0.670 t / m
( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.912 ) = 1.175 m
( 2.395 / 1.175 ) = 2.038 t / m
( 2.453 / 1.175 ) = 2.088 t / m
( 8.533 / 1.175 ) = 7.262 t / m
( 3.013 / 1.175 ) = 2.564 t / m
( 1.706 / 1.175 ) = 1.452 t / m
( 1.712 / 1.175 ) = 1.457 t / m 1.186 t / m
( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.912 ) = 1.175 m
( 1.901 / 1.175 ) = 1.618 t / m
( 1.710 / 1.175 ) = 1.455 t / m
( 2.484 / 1.175 ) = 2.114 t / m
( 2.903 / 1.175 ) = 2.471 t / m
( 2.820 / 1.175 ) = 2.400 t / m
( 2.469 / 1.175 ) = 2.101 t / m
0.855 t / m
for 17 t wheel
For Max BM (Hogging) at End web
Corresponding base pressure =
For Max BM (Hogging) at Start of haunch2
for 12 t wheel
for 12 t wheel
for 17 t wheel
for 17 t wheel
for 17 t wheel
Corresponding base pressure =
For Max BM (Hogging) at middle web
Live load intensity as udl
Disp. width of 17t load at start =
Disp. width of 17t,12t & 8t load =
for 17 t wheel
for 17 t wheel
for 17 t wheel
Corresponding base pressure =
Live load intensity as udl
Live load intensity as udl
Disp. width of 17 t &12t wh. =
Disp. width of 12 t wh.at end =
for 17 t wheel
for 17 t wheel
for 17 t wheel
for 17 t wheel
Corresponding base pressure =
LOAD INTENSITY AND CORRESPONDING BASE PRESSURE FOR CLASS 70R WHEELED:
Dispersion width = wheel length over the span after 45odispersion through wearing coat and slab
for 17 t wheel
for 17 t wheel
for 17 t wheel
for 12 t wheel
for 12 t wheel
Disp. width of 17t & 12t load =
Disp. width of 12 t load at end =
for 17 t wheel
For Max BM (Hogging) in mid span
Live load intensity as udl
Disp. width of 12t load at start =
Disp. width of 12t & 17t Load =
for 17 t wheel
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( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.456 ) = 0.719 m
( 2.735 / 1.175 ) = 2.328 t / m
( 2.471 / 1.175 ) = 2.103 t / m
( 2.620 / 1.175 ) = 2.230 t / m
( 3.643 / 1.175 ) = 3.100 t / m 0.687 t / m
( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.912 ) = 1.175 m
( 2.552 / 1.175 ) = 2.172 t / m
( 2.429 / 1.175 ) = 2.067 t / m
( 1.827 / 1.175 ) = 1.555 t / m
( 2.572 / 1.175 ) = 2.189 t / m
( 1.151 / 1.175 ) = 0.980 t / m
0.631 t / m
( 0.263 + 0.912 ) = 1.175 m
( 0.263 + 0.912 ) = 1.175 m
( 2.784 / 0.912 ) = 3.053 t / m
( 2.462 / 0.912 ) = 2.700 t / m
0.314 t / m
For Max BM (Sagging) at end of huunch 9
Live load intensity as udl
Disp. width of 17t load at start =
Disp. width of 17t,12t & 8t load =
Corresponding base pressure =
for 17 t wheel
for 17 t wheel
for 17 t wheel
for 17 t wheel
For Max BM (Sagging) in mid span
Disp. width of 17t load at start =
Disp. width of 17t,12t & 8t load =
Live load intensity as udl
for 17 t wheel
for 17 t wheel
for 12 t wheel
for 12 t wheel
for 8 t wheel
Corresponding base pressure =
For Max BM (Sagging) at end of haunch 1
Live load intensity as udl
Corresponding base pressure =
for 17 t wheel
for 17 t wheel
Disp. width of 17t load at start =
Disp. width of 17t,12t & 8t load =
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1.1
1.25
Max. Max. Max. Max. Max. Max.
sagging hogging sagging hogging sagging hogging
At the face of end web -1.914 4.862 -1.788 3.75 -1.914 4.862
At the end of haunch-1 -3.322 0 -3.175 0 -3.322 0
mid span -7.128 1.254 -5.95 1.265 -7.128 1.265
At the start of haunch-2 0 3.322 -0.338 3.375 -0.338 3.375
At the end of haunch- 2 0 8.492 0 11.938 0 11.938
At the face of end web 0 1.31 0 1.49 0 1.49
At the end of haunch-1 -1.82 0 -2.14 0 -2.14 0
mid span -2.67 0 -3.67 0 -3.67 0
At the start of haunch-2 0 2.52 0 2.85 0 2.85
At the end of haunch 0 5.715 0 8.24 0 8.24
0 1.903 0 3.875 0 3.8750.000
2.706
0.000
3.750
0.000
3.750-0.110
3.960
0.000
3.988 -
0.1103.988-1.045
5.324 -
0.863
5.025 -
1.045
5.324
SUMMARY OF BENDING MOMENT AT DIFFERENT LOCATION
(I) Due to LIVE LOAD
Impact factor (I.F.) for class 70R tracked =
Impact factor (I.F.) for class 70R wheeled =
CLASS CLASS
BOTTOM
SLAB
70R(Wheeled)70R(Tracked)
DESIGN BM
LL
LOCATION
TOP
SLAB
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-1.936
6.600 -
1.800
5.975 -
1.936
6.600
-2.6732.354 -
2.513
2.938 -
2.673
2.938
-0.715
0.517 -
0.613
0.788 -
0.715
0.788
-1.496
1.474 -
1.450
1.550 -
1.496
1.550
-3.663
3.465 -
3.500
3.875 -3.663
3.875
-5.665
5.302 -
5.400
6.038 -
5.665
6.038
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