construction of bridges

8/13/2019 Construction of Bridges

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A CULVERTis defined as a structure having a total length of 6.0 M or

less between the inner faces of Dirt walls(Backing wall)

A CAUSEWAYis a structure constructed across a stream which allows the

normal flow of water through its vents and allows the Flood

waters at MFL CONDITION above it. Normally Causeways aredesigned to take 30% of Flood water through vents and

balance to overflow during MFL Condition

A MINOR BRIDGEis a structure having a total length of 60.0m or less

between the inner faces of Dirt walls (BACKING WALLS) i.e.

more than 6.0M and less than 60.0M

DEFINITIONS


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A Major Bridge

is a structure having a total length of more than 60.0

M Between the inner faces of Dirt walls (Backing

walls)

ROB Means a Road Over Bridge

constructed across a Railway line over the Rails. This

means the road traffic passes over the Railway line.

RUB Means a Road Under BridgeConstructed across

a Railway line under the Rails. This means the road

traffic passes under the Railway line. This is lesscostlier, but causes stagnation of water in rainy

season and may cause submersion during y rains.


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WATERThe properties of Water plays very important roll in

achieving the required strength of concrete

(1) The PH of Water should be more than 6

(2) The Sulphate content should be less than

400mg/Litre.

(3) The Chloride content should be less than

500mg/Litre for R.C.C and less than 2000 mg/Litre

for P.C.C


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Curing of water is very important and must be

continued for 28 days irrespective of grade of

cement.

Water used for mixing and curing should be of same

source and of good quality. It is a wrong notion that

Water used for Curing need not be of good quality

In case of Structures near Sea coast Potable water may

not be available. In such cases Extra water lead may be

included in Estimate and insisted during Execution.

Adequate number of COVER BLOCKS with Binding wire

fixed may be casted and cured well in advance not less

than 15 days and CURED under water before laying

concrete and placed under Reinforcement.


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PIPE CULVERTS

(1) The Depth of Foundation for Pipe culvert should

be 0.90M Below sill level as per IRC SP-13, WITH Bed

protection. It may be increased to 1.20M Below silllevel WITHOUT Bed protection.

(2) The Sill level may be fixed at 0.15M Below

existing Bed Level.

(3) The Width of Body wall at bottom may be fixed

as (0.40H+0.30) where H IS HEIGHT OF WALL in

Meters

(4) In case of multiple row Pipe Culvert the distance

between the pipes should be not less than the

Outer diameter of pipe subject to a minimum of

450mm.


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SLAB CULVERTS

(1) Slab Culverts are effective in discharging flood

waters compared to Pipe culverts even though the

construction takes little more time. The Pipe Culvertsare likely to get choked due to Debris, Jungle etc in

vents during floods.

(2) IRC SP-13 gives the sections of Abutments, Wing

walls for different heights, sections of Deck slab and

Reinforcement for Spans ranging from 1.0M to 6.0M

(3) The Sections in IRC SP-13 are applicable for soilswith a S.B.C. of not less than 16.50 T/M2. For lower

S.B.C. Values of foundation soils Raft foundation

may be adopted.


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CAUSEWAY WITH GUIDE POSTS


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FOUNDATIONS

SHALLOW FOUNDATION(< 4M) DEEP FOUNDATIONS(>4M)

RAFT INDIVIDUAL

FOOTINGS

WELL

FOUNDATION

PILE

FOUNDATION


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(1) Raft Foundation is adopted when the S.B.C. of

Foundation soil is less than or equal to 10T/M2 like

Black cotton soils, marshy soils with small spanarrangement.

(2) Individual Footings are adopted when the S.B.C of

the Foundation soil is more than 16.50T/M2.

(3) This type of foundations are suitable when HARD

soils are met at shallow depths and in case of ROB/

RUB where there will not be any scour likely to

occur as there will not be any flow.

(4) Suitably designed Aprons are to be provided

both on Upstream side and on Downstream side to

Protect the Bridge structure.

OPEN FOUNDATIONS


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EARTH WORK FOR OPEN FOUNDATION IN SANDY SOIL


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EARTH WORK FOR OPEN FOUNDATION IN SANDY SOIL


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Earth work excavation for open foundations in sandy soils. As it is difficult to excavateindividual foundation trenches, the excavation was done continuously like a canal. Asit is in the heart of town limits shoring and shuttering adopted to avoid sliding of sandand damage to adjoining railway quarters as they demanded total cost of structureson the plea that there quarts will be collapsed.

OPEN FOUNDATION FOR INDIVIDUAL FOOTING IN SANDY SOIL


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LAYING OF CEMENT CONCRETE BED 100 MM THICK UNDER PIER

FOOTING


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Reinforcement completed for pier footings. A beam connecting the three circularpiers can be seen above the footing reinforcement. The center to center distanceof piers should be verified carefully and main reinforcement of pier should beplaced at exact location before laying concrete for pier footing.


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A trapezoidal

section was

adopted for pier

footing.

Hence the topreinforcement

was to be bent

accordingly to

suit the concrete

section with a

cover of 50 mm


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Laying of plain concrete for Abutment foundations in V.C.C. M15 using 40 mmgraded metal. Each layer should not exceed 200 mm for proper vibration of eachlayer. Shear keys in the form of holes may be provided by keeping concrete blocksin each layer of concrete and removing the same after one hour to leave holes andto act as key.


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Concrete completed for pier footing. A trapezium section with a beam connecting 3circular piers of 1.0 m dia. can be seen. The shutters should be thoroughly checked formaintaining three piers in one line and at exact distance to avoid variation in span.


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Circular piers of 1.0 m dia. completed by laying concrete in each stage of

2.50 m inside face of sloped face of Abutment can be seen with weep holes.


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PHOTO SHOWING WELL CUTTING EDGE AND WELL CURB


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PHOTO SHOWING TREMIE PIPEFOR BOTTOM PLUGGING OF

WELL.


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WEEP HOLES IN ABUTMENT


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Filter media using 50% of 150 mm HBG stone and 50% of 40 mm HBG metal were placed behindRetaining walls to allow seepage water to drain off easily in to weep holes. As the formation is to befilled with sandy soils, 0.60 m thick Gravel Backing adjoining the filter media is provided to avoidscooping out of sand with seepage water from pavement, other wise Gravel Backing adjoining filtermedia is not necessary

REINFORCEMENT OF R C C DECK SLAB FOR 10 0 M SPAN


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REINFORCEMENT OF R.C.C. DECK SLAB FOR 10.0 M SPAN


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ELASTOMER UNITS 40MM THICK 0.75M OR 1.0M LENGTH


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SLAB SEAL TYPE


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STRIP SEAL EXPANSION JOINT FOR LARGER MOVEMENTS

ELASTOMER SEAL

I .S ANGLES

ANCHOR

RODS

ANCHOR RODS


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CLOSER VIEW OF STRIP SEAL WITH ELASTOMERS

CLOSER VIEW OF STRIP SEAL JOINT AT APPROACH SLAB


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Fixing of strip seal joint with main reinforcement of

superstructure in the recess of concrete

Close view of fixing of strip seal joint with main reinforcement

of super structure


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of super structure


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Camber should be provided in joints itself at RCL and should

extend in to kerb portion also duly welded to main reinforcement


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The top level of strip seal joint shall be kept equal to top level of

wearing coat and care must be taken that no jerk is observed at

joints.


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ELASTOMER STRIPS IN ROLLS AND FIXING IN JOINT


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CLOSER VIEW OF FIXING ELASTOMER IN ANGLE ATACHMENT


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T- BEAM GIRDERS SEEN FROM BOTTOM


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BRIDGE COMPLETED


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PIER

WELL AFTER SCOUR

DECK SLAB COLAPSED


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WELL AFTERSCOUR

DECK SLABS COLLAPSED

PIER


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REINFORCEMENT CORRODED DUE TO INADEQUATE COVER


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DECK SLAB REINFORCEMENT CORRODED AND EXPOSED


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MINOR BRIDGE COLAPSED DUE TO CORROSION OF STEEL

LOAD TEST FOR BRIDGE 70R LOADING


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The load is to be accommodated in the span which gives maximum bending

moment. For 10m clear span the critical load works out to 68.0 MT (4x17.0

MT). For other spans this will be different. This critical load is to be increased

by 25% as per is 456-2000

LOADING FOR CLASS 70R LOAD AS PER APPENDIX I OF IRC 6-2000

TRACKED VEHICLE :70.0M.T WHEELED VEHICLE :100.0 M.T

LOAD TEST FOR BRIDGE 70R LOADING

CONTACT AREA :610X410 MMTOTAL LENGTH OF VEHICLE

:14.31OM

THE LOADING SHALL BE DONE AT 30%,50%,70%, 80%,90%,100%


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THE LOADINGSHALL BE DONE AT 30%,50%,70%, 80%,90%,100%0F TOTAL LOAD.

THE MAXIMUM DEFLECTION PERMISSIBLE IS 40L2

/D (WHERE LIS THE EFFECTIVE SPAN),AS PER CLAUSE 17.6.3.1 OF IS 456-2000 WHICH WORKS OUT TO 5.33mm FOR 10.76M C/C SPAN.

THE STRUCTURE SHOULD HAVE A RECOVERY OF NOT LESS

THAN 75% OF MAXIMUM DEFLECTION DUE TO SUPERIMPOSEDLOAD ON REMOVAL, AS PER CLAUSE 17.6.3 OF IS 456-2000.

THE SUPERIMPOSED LOAD SHALL BE KEPT FOR 24 HOURS ANDDEFLECTIONS RECORDED


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LOAD TEST ON R.O.B. MARKAPUR WITH STEEL PLATES OF610X410X25 MM EACH TAKING A LOAD OF 10.625 M.T


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LOADING WITH SAND BAGS EACHWEIGHING 35 KG


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LOAD TEST WITH PLATES 610X410MM FOR 70R LOADING


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CLOSE UP VIEW OF LOADED PLATES 610X410 MM, ISBEAMS, PLOTFORM


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CLOSE UP VIEW OF LOADED PLOTFORM, CHANNELS,IS ANGLES,PLATES


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SIDE VIEW OF PLOTFORM WITH SAND BAGS EACHWEIGHING 35 KG


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LOADED PLOTFORMS 2 NO. EACH WITH 4 SETS OF PLATES.LOAD ON EACH SET OF PLATES IS 10.625 M.T


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LOADED PLATFORMS 2 NO, EACH WITH 4 SETS OF PLATES.

LOAD ON EACH PLATE IS 10.625 M.T .

TOTAL LOAD IS 8X10.625 = 85.0 M.T


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LOADING PLOTFORMS EACH CARRYING 42.5 M.TTOTALLING TO 85.0 M.T FOR 10 M CLEAR SPAN`


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DIAL GUAGES UNDER SLAB FOR MEASURING DEFLECTIONS3 NO. ALONG SPAN+ 2 NO. TRANSVERSE DIRECTION


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CLOSE UP VIEW OF DIAL GUAGES FOR MEASURINGDEFLECTIONS, PLOTFORMS

RESULTS OF LOAD TEST


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DEFLECTOMETERIDENTIFICATIONMEMBERLOCATION

DEFLECTION AFTER24 HOURSLOADING(MM)

DEFLECTIO

N DUE TOTEMPERATUREDURINGLOADPERIOD(7 AM TO

6PM)IN MM

CORRECTEDDEFLECTION

(MM)

LIMITINGDEFLECTION

(MM)

MAX

VALUEASPERANALYSIS

(MM)

%RECOVER

YAFTER 24HOURSOFLOADING

D1R/S

END1.17

0.92

UPWARD2.09

5.33

mm

6.9

085.6%

D2

CENTR

E OF

DECK

0.841.15

UPWARD1.99 -do- -do 89.4%

D3L/S

END0.46

0.77

UPWARD1.23 -do- -do- 86.2%

D4 SPAN 0.940.77UPW

ARD1.71 -do- -do- 87.1%

D5 SPAN 0.73 0.73UPWARD

1.46 -do- -do- 80.1%

LEAST COUNT =0.01mm MAX TRAVEL = 50mmDEFLECTIONS DUE TO LOADING

CONCLUDING REMARKS


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1) From the results of load test ,the maximum deflectionrecorded is 2.09 mm ,against the limiting deflection of5.33mm,as per clause 17.6.3 of IS 456-2000.

2) The deflection recovery of the Deck slab was found to bemore than Stipulated minimum of recovery of 75 afterremoval of test load.3) Hence it can be concluded that the deflection behavior ofthe Deck slab of the bridge is within the permissible limits.


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THANK YOU

For further clarification and comments

Sri P.SURESHDEPUTY EXECUTIVE ENGINEER(R&B) SUB DIVISION, UDAYAGIRI

9440818349

construction of bridges

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