RCC Box RD-21060 PDF
November 26, 2022 | Author: Anonymous | Category: N/A
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INDEX Sr. No.
Content
1.0
Introduction & Reference Codes
1.1
Design Calculations of Minor Bridge
2.0
Load Calculations
3.0
Effective Width Calculation for Live Load
4.0
Calculation of Modulous of Subgrade Reaction
5.0
Calculation of Temperature Effect
6.0
Calculation of Creep Coefficient
7.0
Bending Moment & Shear Force Calculation & their checks
8.0
Calculation of Base Pres Presssure ssure
9.0
Staad Input
1
1.0 Introduction and Reference Codes 1)
Structure Details
a)
Str Struct uctur ure e Type Type
:‐
b)
Proposed Design Chainage
:‐
21060
c)
Si Sizze
:‐
1 x 4.5 x 2.5
d)
Box Width upto centre of Median
:‐
5.3 m
e)
Earth Cushion (max)
:‐
0.0 m
2)
Materials Used
a)
Grade of Concrete for Box Structure
:‐
M 30
b)
Grade of Steel :
:‐
M 415
3)
Co Codes des Us Used ed :
a)
IRC 6 : 2014 2014 Code of Practice for R Road oad br bridges, idges, S Sec‐II ec‐II : Loads & Stresses
b)
IRC 112 : 2 2011 011 Code of Practice for Concrete Road bridges
c)
IRC 78 : 2014 Code for Practice for Road b bridges, ridges, Sec‐VI : Foundations Foundations & Substructure Substructure
4)
Modeling Modeling and Analysis Analysis considerat considerations ions : Structure is idealized as plane frame centre to centre of components, of unit width and analysed using STAAD Pro.
a)
b) c) d) e) f)
5)
RCC Box Minor Bridge
Bottom slab iiss assum assumed ed to be spported spported on nu number mber of sp springs. rings. Modulus of Subgrade Subgrade Reaction has been been calcu calculated lated as per J. E. Bowles For analysis, the box model is subjected to Dead loads, SIDL ,Earth pressures,Surcharge loads on the side walls, and Live Loads. 3 Lane vehicle loading conforming to IRC‐6 :2014 is used. The dispersion of live load is calculated using effective slab width method as per Annexure B‐3 of IRC 112‐2011.
Design Design Phi Philos losophy ophy : Various combination combination of loads are adopted for checking structural strength & Serviceability Serviceability Limit State
a) Ultimate Limit State (ULS) :‐ For structural strength of various components. b) Seviceability Limit State (SLS) :‐ Rare combination are adopted to check the stresses in various components Quasi‐permanent Quasi‐perm anent Combinations adopted for checking the crack width. 6)
Environment Environment Condit Condition ion Consi Considered: dered: Environmental Environmen tal exposure condition for the structure is considered as
Moderate
(as defined in Table 14.1 of IRC ‐112 ) 7)
Constructio Construction n Sequence Sequence Consi Considered: dered: The following construction sequance has been considered in the design. Lay the bottom slab‐ then side wall‐ then cast the Top slab. Filling shall be done behind both end wall or abutment walls simultaneously.
2
DESIGN CALCULATIONS OF MINOR BRIDGE 1.0 DESIGN DATA 1.1 GENERAL INFORMATION
3
RCC Box Minor Bridge Wearing Coat = 0.065m
Earth Cushion 0.000 0.400
Haunch of 0.000
0.25 x 0.25
2.50
0.000
4.50
0.400
4.500
0.000 4.500
Base pressure =
3.9 t/m2
10.0 t/m2
<
Hence, OK
1.2 DIMENSION DETAILS No of cells
=
Skew Angle
=
Effective Span C/C
=
Effective Span C/C
(Skew)
=
Clear Span Clear Span
= (Skew)
=
Clear Height (Max)
1x 1x 1x 1x
=
Width of Box
=
Width of Box (Skew)
=
We Wear arin ing g co coat at th thic ickn knes esss (O (Ove verl rlay ayin ing g ta take ken n into into co cons nsid ider erat atio ion) n)
=
Max Max Ht of fi fill ll (W.C (W.C / P.C. P.C.C C / pa pave veme ment nt laye layers rs)) ov over er th the e top top slab slab
=
Mi Min n Ht of fi fill ll (W (W.C .C / P. P.C. C.C C / pa pave veme ment nt laye layers rs)) over over th the e to top p slab slab
=
Thickness of Top slab Thickness of Bottom slab
= =
Thickness of External Vertical Wall
=
Thickness of Internal Vertical Wall
=
Size of Haunch
=
Width of Parapet Wall/ Crash Barrier
=
x
Width of Safety kerb
=
Dis Distan tance ce of ed edge ge of pa parap rapet et wall/C wall/Cras rash h Bar Barrie rierr from from edg edge e of bo boxx
=
Height of surcharge
=
Safe Bearing Capacity of the soil
=
Permissible Settlement
=
10 mm
=
1 0 4. 4.90 900 0 4. 4.90 900 0 4. 4.50 500 0 4. 4.50 500 0 2.50 5.30 5.30 0.065 0.000 0.000
No. No.ss deg. m m m m m m m m m m
0.400 m 0.400 m 0.400 m 0.000 m 0.250 m 0.250 m 0.450 m 0.000 m 0.225 m 1.200 m 10.0 t/m 0.01 m
2
4
1.3 MATERIAL PROPERTIES 3
Density of concrete
=
25 KN/m
Density of soil
=
20 KN/m
Density of wearing coat
=
Angle of internal friction (in degree)
=
Coefficient of earth pressure at rest
=
Coefficient of active earth pressure
=
22 KN/m 18 deg 0.691 0.528
Grade of Concrete
=
Grade of Reinforcement
=
Clear Cover for earth face structural component
=
M 30 Fe 415 0.075 m
Cl Clea earr Cove Coverr fo forr in insi side de face face// to top p slab slab stru struct ctur ural al co comp mpon onen entt
=
Clear Cover for bottom slab
=
0.040 m 0.075 m
3 3
1.4 DESIGN PARAMETERS
5
2.0 LOAD CALCULATIONS FOR THE BOX STRUCTURE 2.1 DEAD LOAD Self weight of the structure has been calculated directly in STAAD file by the comment "SELFWEIGHT ‐1". 2.2 SUPER IMPOSED DEAD LOAD Wearing coat thickness
=
0.065 m
Load (UDL) (UDL) on top slab due to Wear Wearing ing coat
=
1.43 1.430 0 kN/m
Ht of fi fill ll (T (Thi hick ckne ness ss of W.C W.C / P. P.C. C.C C / pave paveme ment nt laye layers rs)( )(Co Cons nsid ider erin ing g Avg. Avg. Ht. Ht. of fi fill ll))
=
0.00 0.00 m
Lo Load ad (U (UDL DL)) on to top p sl slab ab
=
0. 0.00 00 kN kN/m /m
Wt of Parapet Wall/Crash Barrier
=
8.00 kN/m 8.
Wt of Safe Safety ty ke kerb rb
=
5.00 5.00 kN kN/m /m
Footpath Loading
=
0.00 kN/m
Total UDL load due to S.I Dead Load
=
13.0 kN/m
2.3 EARTH PRESSURE Thickness of top slab
=
0.400 m
Height of top haunch
=
0.250 m
Clear height between top & bottom slab
=
2.500 m
Height of bottom haunch
=
0.250 m
Thickness of bottom slab
=
0.400 m
Earth Pressure at Rest Height from top
Intensity of Earth pressure 2
(m) 0.200
0.200
(KN/m ) 0.690983005625053 x 20 x 0.200
0.200
0.200
0.690983005625053 x 20 x 0.200
=
2.764
=
2.764
Active Earth Pressure Height from top
Intensity of Earth pressure 2
(m) 0.200
0.200
(KN/m ) 0 .5 .5 27 27864045000421 x 2 0 x 0.20 .200
0.200
0.200
0.527864045000421 x 20 x 0.200
=
2.11 .112
=
2.112
6
2.4 LIVE LOAD SURCHARGE Equi Equiva vale lent nt heig height ht
=
Uniform Intensity of loading (f o orr Active condition) = Uniform Intensity of loading (for Rest condition) =
1.2 x 0.528 x 20 1.2 x 0.691 x 20
=
1.20 1.20 m 2
kN/m 12.67 kN/m 12.67
3
=
kN/m 16.6 kN/m 16.6
=
140 140 kN kN
26.4 kN 26.4 kN
2.5 BRAKING LOAD Carriageway Live Load
(700*0.2)
Width of the box
=
Braking Load
=
5.3 m
2.6 CALCULATING BRIDGE TEMPERATURE : Maximum air shade temperature
=
45 o C
Minimum air shade temperature
=
7.5 oC
Bridge Temperature
=
36.3 oC
7
3.0 Effective width of tyres and load distribution for different different vehicular loadings: Effective span Total Width of Box culvert
lo b
= =
4.90 m 5.30 m
= =
0.065 m 0.400 m
Width of Crash barrier / Kerb
=
0.45 m
Dist. of edge of crash barrier/guard stone from edge of box
=
0.23 m
Wi Widt dth/ h/Ef Effe fect ctiv ive e Sp Span an ra rati tio o
=
1.08
=
2.27
Ht of fill (W.C / P.C.C / pavement layers) Thickness of deck slab
b / lo
=
5.300 / 4.900
As per Cl. B3.2 of IRC:112‐2011(Page‐278), IRC:112‐2011(Page‐278), for continous slab For
b / lo
=
1.08
;
a
8
9
10
3.2 Class ‐A vehicle: 3.2.1 Single Lane Class A
(Refer: Clause 204.1.3, Fig.1, IRC : 6‐2014 )
5.7 t
5.7 t
11.4 t
11.4 t
1800
1300
500
500 1200
2300
Total Load Impact factor
Transverse
Longitudinal
= =
= =
(Refer Cl.208.2 of IRC:6‐2014)
22.80 t 1.413
Minimum clear dista Minimum distance nce from Crash Barrier Barrier to the edge of the end wheel wheel Distance between the axles in the direction of traffic c/c distance between end wheels in transverse direction
= = =
0.15 m 1.20 m 1.80 m
Contact width of tyre Contact breadth of tyre
= =
500 mm 250 mm
Contact area
=
Contact width of tyre in a direc ttiion perpendicular to the span Wheel dimension perpendicular to span Distance from outer edge of kerb to c.g of wheel
= = =
Effective width a b1
α a (1 ‐ a / lo) + b 1
= = = =
500 x 250 mm 0.50 m 0.50 m 0.63 m
(Refer Cl. B3.2 of IRC:112‐201 IRC:112‐2011) 1)
th the e di dist stan ance ce of c. c.g g of conc concen entr trat ated ed load load from from near nearer er supp suppor ortt 4..9 / 2 ‐ 1.2 / 2 4 = 0.5 + 2 x 0.065 =
1.850 m 0.63 m
Ef Effe fect ctiv ive e wi widt dth h = 2. 2.27 2726 2653 5306 0612 1224 2449 49 x 1. 1.85 85 x (1 ‐ 1. 1.85 85 / 4. 4.9) 9) + (Dispersion width crosses the deck slab) (Dispersion width of two wheels overlaps in trans direction)
= >
Effective load in transverse direction
=
11.40 t
=
4.049 m
0.85 Crash Barrier 0.45
1.800
0.15
0.50
Effective width for design (In transverse direction)
Total load Dispersion area Load per unit area Load per unit area with I.F
1.30
0.50
Dispersion along span direction (Refer Cl. B3.3 of IRC:112‐2011) Dispersion width for design (In longitudinal direction)
3.25 3.25 m 1.8 m
=
0.25 + 2 x (0.065 + 0.4)
= <
1.18 m 1.200
=
IF IF(1 (1.1 .18> 8>1. 1.2, 2,(1 (1.1 .18 8 + 1. 1.2) 2),1 ,1.1 .18) 8)
=
1.18 1.180 0m
= =
4.049 x 1.18 11.4 / 4.778
= = =
11.4 t 2 4.78 m 2 2.39 t/m
=
2. 2.39 x 1.413
=
3.38 t/m
2
11
12
13
3.4 Summary of Intensity of Loads: Loading 1 Lane Class A Design LL intensity for analysis
2
Intensity of Load (t/m ) 3.377 = =
3.377 t/m 33.77 kN/m 33.77 kN/m
14
Calculation of Vertical Subgrade Reaction : The structure as shown is idealised in STAAD. The The vertical soil resistance at bottom has been applied in the form of springs. The value of spring constants has been calculated based on the permissible settlement and bearing capacity. The bottom slab of structure is idealised as shown in following figure. The equivalent spring is applied at each node according to subgrade reaction.
4.700
2.900
1
2
3
4
5
6
7 8
Input Data Thickness of outer wall Thickness of top slab Thickness of bottom slab Thi ck ckness ess of inter ter m med ediiate ate wal alll Haunch
= = = = =
Clear span (Skew) Clear Height
= =
4500 mm 2500 mm
SBC Permissible settlement
= =
10 t m 10 mm
400 400 400 0 250
9
10 10
1 11 1
12 12
13
14
15
mm mm mm mm mm
2
15
Support No
K Value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
250 500 362 1379 2534 2233 1931 1931 1931 2233 2534 1379 362 500 500 500 362 1379 2534 2233 1931 1931 1931 2233 2534 1379
27 28 29
362 500 250
16
EFFECT OF TEMPERATURE OVER BOX STRUCTURE CALCULATING BRIDGE TEMPERATURE : o
Maximum air shade temperature
=
45 C
Minimum air shade temperature
=
7.5 oC
Bridge Temperature
=
36.25 oC
Ec = Modulus of Elasticity of Concrete
=
3.18E+06 t/m2
α= Coefficient of Thermal expansion Δt = Temperature differential differential
=
1.20E‐05 /oC
Calculating equivalent equivalent Temperature for gradient temperature effect : F = E c α Δt A
A = Cross‐sectional Area of section where temperature differential is Δt
Thickness of top slab
=
400 mm
EFFECT OF TEMPERATURE RISE: 17.8 1
2 1 . 0
2 4 S No.
0 2 1 . 0
3
1 2 3 4
Δt degree 4.0 13.8 4.0 2.1
b m 1.00 1.00 1.00 1.0 1.00 0
Acting at F t m From 18.31 0.06 top 63.17 0.04 top 18.31 0 .1 .160 top 9.61 .613 0 ..0 04 bot botto tom m 109.4
t A m m2 0.12 0.12 0.12 0.12 0.12 0.12 0.12 .12 0.12 .12 ∑F =
e m 0.34 0.36 0.240 ‐0.3 ‐0.36 6
Moment tm 6.226 22.743 4.395 ‐3.461 29.902
e* = Eccentricity of force F from centroid centroid axis of Section
2
4
1 . 0
27
2.1
M = F.e =>
= Ec x α x (Δt/2) x A x e 15.26 x Δt/2 x
29.902 =
0.15
400
o Δt = 27.03 C
=>
Idealised Temp Gradient ( +ve )
EFFECT OF TEMPERATURE FALL: 9.9 0.7 2 1 80
3
100.0
40
6
S No.
1 2 3 4 5
Δt degree 0.7 9.9 0.7 5.8 0.8
6
0.8
100.0 = F.e M
4 5.8
5 0.8
80
b m 1.00 1.00 1.00 1.00 1.00
t m 0.080 0.080 0.100 0.080 0.080
A 2
m 0.08 0.08 0.1 0.08 0.0 0.08 8
1.00 0.100 0.1 0.1 ∑F =
F t 2 2..136 30.21 2.67 17.7 2.44 2.442 2
3.05 3.052 2 0.113 58.21
= Ec x α x (Δt/2) x A x e
=> 4.452 = 15.259 x Δt/2 x =>
Acting at e Moment m From m tm tm 0 0..04 top 0. 0.36 0.769 0 0..027 top 0. 0.37 373 3 11.2 11.280 80 0 0..113 top 0.28 .287 0.76 .766 0.027 bottom ‐0.3 ‐0.373 73 ‐6.6 ‐6.608 08 0.04 bottom ‐0.3 ‐0.360 60 ‐0.8 ‐0.879 79
Δt =
o
4.02 C
bottom ‐0.2 ‐0.287 87
‐0.8 ‐0.875 75 4.452
4.02
0.15
400
Idealised Temp Gradient ( ‐ve )
17
S Showing howing Temperature differences For Box ( + ve temperature gradient) o
Temp = 27.0 27.03 3 C 5 . 3 1 = p m e T
Temp =
0 oC
0 = p m e T
0 = p m e T
5 . 3 1 = p m e T
0 = p m e T
1 0 . 2 = p m e T
S Showing howing Temperature differences For Box ( ‐ ve temperature gradient) Temp = 4.02 4.024 4 oC 1 0 . 2 = p m e T
Temp =
o
0 C
0 = p m e T
Showing Showing Temperature for overall for expansion / contracon
o
Temp = + 36.2 36.25 5 C
Note:
For +ve temperature case top slab will be Hotter than bottom, as shown in Fig., For side wall Inner side Temperature is kept same as that of bottom of top slab, and as earth is present behind the walls, hence outer side of wall will be cooler than the Inner side of wall. Temperature difference of side wall is assumed as half of the temperature of the top slab. For bottom slab No Temperature difference is considered as it is embedded in earth. The Same Philosophy is adopted for ‐ve temperature difference. For Overall Bridge Temperature Temperature elongat elongation/ ion/ contrac contraction tion is cons consider idered ed only for the top slab, on the conservative side.
18
Finding Creep Co‐Efficent : f ck
=
30 Mpa
f cm
=
40 Mpa
t to
= =
25550 days 90 days
f (t, to)
=
f o bc( t , to )
f o
=
f RH b(f cm) b(to)
f RH
=
1 ‐ RH/100
1+
0.1 ( ho )
0.1 ( ho )
= =
α1
α2
=
β(f cm)
=
β(to)
0.2
[ 43.75 / f cm ]
=
2.969
=
βH
0.7
[ 43.75 / f cm ]
18.78 / √fcm
βc( t , to) =
≤
45 Mpa M pa
1/3
α1
* α2
for f cm
>
45 Mpa M pa
Relative humidity 80 %
=
=
for f cm
1/3
1 ‐ RH/100
1+
RH
APPENDIX A2.5
=
1.065
=
1.018
(As per IRC 112‐2011, pg 239)
0.2
1/ (0.1+ to )
0.391
=
0.3
[ (t‐to) / (βH + t ‐to) ]
Min
18
1.5 [ 1+ (0.012 RH) ] h o + 250
for fcm
≤
M pa 45 Mpa
for f cm
>
M pa 45 Mpa
1500
Min
18
1.5 [ 1+ (0.012 RH) ] h o + 250 α3
1500* α3
α3
=
0.5
[ 43.75 / f cm ]
Ac Member
2
mm
U mm
=
1.046
ho mm
ΦRH
Φo
bH
bc( t , to) Φ (t, to)
1.47
Top slab
1960000 10600
369.81
1.28
1. 1.48 48
1070 1070.7 .76 6
0.99
Side wall
1000000
5800 5800
34 344. 4.83 83
1.29
1.49
1015 1015.3 .31 1
0.99 0.99
1.47
Base slab
1960000 10600
369.81
1.28
1.48
1070.76
0.99
1.47
19
Summary of Bending Moment and Shear Force from STAAD File Bending Moment (KN‐m) Member
Case
Shear Force (KN)
Section ULS
SLS (Rare)
SLS (QP)
ULS
Sagging Mid Span
165
110
18
197
Hogging Face of Support
130
91
40
197
Sagging Mid Span
25
23
15
70
Hogging Face of Support
192
132
25
148
Top Slab
Side Wall
20
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