METHOD OF CONSTRUCTION METHOD OF CONSTRUCTION OF SEGMENTAL CONCRETE OF SEGMENTAL CONCRETE

BRIDGEBRIDGE

By ,

P P AMBEDKAR

Objective Of Dissertation work

Construction of segmental bridge involves use of different machineries and requires huge amount of skilled manpower. Hence the intention of dissertation is to study the Methods & techniques used in Construction of Segmental Bridge by Under Slung Method which consist of following activities.

1. Construction of Sub-structure

2. Construction of super-structure

Development of precast segmental bridge construction

First segmental bridge

Second segmental bridge

Segmental bridges in India

What is segmental construction

Pier

PC segmentsPrestressing cables

Method of construction of segmental bridge

1.Cast-in-Place Segmental Construction (Balance Cantilever method)

Bridge across the Lahn River in Germany

2. Precast Segmental Construction

Flyover at Agriculture College Pune

General design consideration

Principal Dimension of Segment

W = Top Slab width

D = Construction depth

B = Bottom slab width

L = Segment length

Construction of substructure

Cast-in-situ Pile

Detailed breakdown of activities is mentioned below

1. Setting Out2. Removal of Overburden3. Driving Permanent Liner4. Boring / Chiseling5. Reinforcement Cage Lowering6. Concreting

1. Setting Out

2. Removal of overburden3. Driving permanent liner

Tripod

Driving cap

Driving monkey

Liner

4. Boring/ Chiseling

BAILER

CHISEL

BailerExcavated mud

Removing of excavated material with help of bailer

5. Reinforcement cage lowering 6.Concreting

Chute

Funnel

Tremie pipe

Major Equipment Required

1) F 35d/d winch - 4 no

2) Pile driving tools & accessories - 4 set

3) Tripod - 4 set

4) Generator 70 KVA - 2 no

5) Welding machine - 2 no

6) Concreting equipments - 2 set

7) Batching Plant - 1 no

TIME CYCLE

Sr.No. Activity Duration

1 Road breaking/removal of top overburden/ Identification of utility services.

2 days

2 Positioning tripod / winch 2 hours

3 Survey & setting out 2 hours

4 Permanent liner driving/ boring 20 hours

5 Chiseling(6m @ 0.1m/hour) 60 hours

6 Cage lowering 2 hours

7 Tremie Pipe lowering/flushing 2 hours

8 Concreting 3 hours

9 Removal of tripod/winch 2 hours

Total time for pilling 93 hours

There fore total time for one pile @ 20hours per day working

4.5 days

Construction Of Pile Cap

Detailed breakdown of activities is mentioned below

1. Clear area for excavation and marking

2. Exaction up to pile cap bottom level i. Excavation in soft soil ii. Chiseling in hard strata

3. Simultaneously chipping of pile

4. Preparation of bed with PCC

5. Cutting and bending and preparation of reinforcement

cage

6. Shuttering for pile cap

7. Concreting

1. Clear area for excavation and marking2. Exaction up to pile cap bottom level i. Excavation in soft soil ii. Chiseling in hard strata

3. Chipping of pile

Bottom of Pile cap Pile chipping by jack

hammer

4. Preparation of bed with PCC

Bed preparation for pile cap by laying PCC

5. Cutting and bending and preparation of reinforcement cage

Pile reinforcement bar

Tying of reinforcement

6. Shuttering

7. Concreting of pile cap

Shuttering

Haizen cloth for curing

MAJOR EQUIPMENTS REQUIRED

1. JCB Excavator 1 No.

2. Dumper 1 No.

3. Breaker (Jack hammer) 2 Nos.

4. Bar bending and cutting machine 1 No.

5. Concrete batching plant 1 No.

6. Transit Mixer 2 Nos.

7. Needle vibrators (60 mm) 2 Nos.

TIME CYCLE Sr.No. Activity Duration

1 Waiting period for curing of pile 7 Days

2 Clearing area, survey and marking for excavation 2 Hours

3 Excavation in soft soil 12 Hours

4 Chiseling in hard rock 2 Days

5 Cutting and removing liner 4 Hours

6 Chipping piles up to pile cap bottom level PCB) 4 Days

7 Preparation of bed with PCC as leveling course 8 Hours

8 Reinforcement cutting, bending and fabricating cage 1 Day

9 Placing and fixing shuttering 3 Hours

10 Concreting 1 HourTotal time = 8.5 days

Construction of Pier

Job breakdown

1. Cutting, and bending of reinforcement

2. Preparation of reinforcement cage

3. Casting Pier starter

4. Erection of staging and simultaneously fixing

shutters

5. Concreting of pier

6. De-shuttering and dismantling staging

7. Curing

1. Cutting, and bending of reinforcement & preparation of reinforcement cage

2.Casting Pier starter

3. Erection of staging and simultaneously fixing shutters

Pier shutter

Staging for supporting pier shutter & providing working platform at top for concreting

4. Concreting of pier

5. Curing

MAJOR EQUIPMENTS REQUIRED

1. HM 101 Crane -1 No2. Bar bending and cutting machine-1 No.3. Concrete batching plant -1 No.4. Transit Mixer - 2 Nos.5. Concrete Pump -1 No.6. D.G. Set -1 No.7. Compressor - 2 Nos.8. Needle vibrators (60 mm) - 2 Nos.

TIME CYCLE

Sr. no. Activity Duration

1 Cutting and Bending Reinforcement 2 Days

2 Tying and Cage Preparation 1 Day

3 Casting Starter and Curing 2 Hrs.

4 Staging and Simultaneously Shuttering 1 Day

5 Concreting 3 Hrs.

6 Waiting till achieving strength for deshuttering 1 Day

7 Deshuttering 12 Hrs.

8 Curing 28 Days

Total time required excluding curing = 3 days

CONSTRUCTION OF APPROCHES

Construction of approach involve two major activity that

are as follows:

i) Construction of Abutment wall.

ii) Construction of Wing wall (Retaining wall)

Types of abutment:

Masonry abutments:

RCC abutments:

R.C.C Abutments

In this case abutment wall is directly rest over raft /pile

foundation. Whole abutment wall made of rich mix concrete. Abutment

wall construction involves following activity:

1. Cutting, and bending of reinforcement

2. Preparation of reinforcement cage

3. Casting abutment starter

4. Erection of staging and simultaneously fixing

shutters

5. Concreting of abutment.

6. De-shuttering and dismantling staging

7. Curing

Staging arrangement

Shuttering

RCC Abutment

The wings walls are of masonry or RCC masonry, now days wings wall are constructed

with new technique that is Geosynthetic Soil Retaining wall in which precast RCC

panel is used. The advantage of this construction system is given below.

1. It requires very limited construction space compared to the conventional wall

systems.

2. The completed structure occupies less space compared to the conventional wall

systems.

3. By using a facing of high rigidity, the stability of the wall system is increased while the

deformation is minimized.

4. The geosynthetic layers are closely spaced so that a wide range of backfill can be

used without affecting performance.

Wing wall

Component of part of GSR Wall

1.Concrete leveling Pad:

2.Precast concrete facing panels

3.Joint material

4.Geogrids

5.Backfill

Construction of Superstructure

Construction of Superstructure of segmental bridge involves two major activities that are as follows:

1) Segment Casting

2) Segment Erection

Different method of segment casting:

1)Long line casting

2)Short line casting

Long line casting

Short line casting

Segment casting involves following activities

1) Base mould preparation

2) Surveying and marking

3)Reinforcement cage leveling

4)Lowering and positioning stopend

5)Placing and fixing inner formwork

6)Concreting and finishing

7)Deshuttering of inner formwork and stopends

8)The segment used for match casting is then placed in the stacking yard and the newly

casted segment is used for next match casting.

1) Pre-cast Bed Survey and Setting out of moulds as per the co-ordinates.

2) Changing/re-fixing of liner material where required and cleaning of beds.

RUBBER LINER

3) Surveying and marking

4) Reinforcement cage lowering:

LIFTING FRAME

REINFORCEMENT CAGE

EOT CRANE

5) Lowering and positioning stopend:

Turn buckels

False work

StopendREINFORCEMENT CAGE

6. Placing and fixing inner-formwork:

Inner formwork

7. Concreting and finishing:

8. Deshuttering INF& Stopend:

9. Lifting and stacking of segments:

MAJOR EQUIPMENTS REQUIRED FOR SEGMENT CASTING

1) EOT 120T Capacity - 1 No.

2) Welding Machine - 2 No.

3) Gas-cutting Equipment - 2 No.

3) Concreting Equipments - 2 Sets

4) Batching Plant - 1 No.

5) Transit Mixer - 2 No.

TIME CYCLE Sr. No. Activity Description Time

Required in Hrs.

1 Base mold cleaning, rectification of rubber liner and applying POP

6

2 Survey and marking 1

3 Lowering reinforcement cage 1/2

4 Lowering and aligning stopend with jacks and knuckle bolts 1

5 Placing and fixing inner-formwork 8

6 Concerting and finishing 3

7 Curing till deshuttering stopend 24

8 Deshuttring stopend 2

9 Curing till deshuttering inner-formwork 46

10 Lifting and stacking segment 1Total time= 92 ½ Hrs

Segment Erection

Probably the most significant classification of segmental bridges

is by method of construction. Although construction methods may be

varied as ingenuity of the designers and the contractor they fall into two

basic categories:

1) Cast-in-Place segmental construction. (Balance Cantilever method)

2) Precast segmental construction.

Cast-in-Place segmental construction

Segment Casting Cycle

Precast segmental construction

1)Segment erection by Crane

2) Segment erection by Winch and Beam

3)Launching Gantry (Over head method)

4)Segment erection by Under-slung method

Segment erection by Under Slung Method Segment erection involves following activities

1. Survey and Barricading

2. Erection of EOT

3. Fabrication and erection of staging

4. Erect sliding trolley with jack arrangement

5. Launch precast segments

6. Temporary pre stressing of segments

7. Permanent pre stressing

1. Survey and Barricading

2. Erection of EOT

Rail track alignment

EOT crane of 125 tone capacity

3. Fabrication and Erection of Staging

Main girder

Seating girder

Concrete block

Cribs

Bracing

4. Erect Sliding Trolley with Jack Arrangement

Screw jacks arrangement with pot bearing

Main girder

Tie box

5. Transportation of precast segment

6. Launch Precast Segments

7. Temporary Prestressing of Segments

Mac-alloy barLifter

Hydraulic machine

Hydraulic pipe

Outside temporary prestressing

Inside temporary prestressing

8. Bearing Installation

8. Permanent Prestressing

TIME CYCLE

Sr. No. Activity Duration

1 Staging Arrangement 1 Day

2 Placing of segments 1.5 Days

3 Dry Matching 0.5 Days

4 Glue and temporary stressing 1.0 Day

5 Install Bearing/ grouting and waiting till attain strength

2.0 Days

6 Permanent pre stressing 0.5 Days

7 Dismantle staging 2 Days

Average Progress: 6 Days per span

Case StudyNAME OF PROJECT: PUNE FLYOVER AT UNIVERSITY CIRCLE & AGRICULTURE COLLAGE.SITE ADDRESS: GANESHKHIND ROAD, UNIVERSITY CIRCLE, PUNE – 411 007

NAME OF CONTRACTOR: AFCONS INFRASTRUCTURE LIMITED NAME EMPLOYER: MAHARASTRA STATE ROAD DEVELOPMENT CORPORATION

NAME CONSULTANT: DAR CONSULTANTS (U.K) LTD. in association with DAR CONSULTANTS (I) PVT. LTD

UNIVERSITY CIRCLE JUNCTION:

GENERAL FEATURES OF UNIVERSITY CIRCLE FLYOVER

1) Length = 700 M between abutments

2) Carriageway = Single three lane carriageway

3) Foundation = Bored cast-in situ piles resting on rock

4) Substructure = RCC Piers

5) Superstructure = Segmental, Deck width – 12 M

AGRICULTURE COLLEGE JUNCTION

GENERAL FEATURES OF AGRICULTURE COLLEGE FLYOVER

1) Length = 210 M between abutments

2) Carriageway = Dual two lane carriageway

3) Foundation = Bored cast-in situ piles resting on rock

4) Substructure = RCC Piers

5) Superstructure = Segmental, Deck width – 16.4 M

The pre-casting Yard includes the following:

Casting Bay : For casting deck segments.

Curing Yard : For curing deck segments.

Stacking Yard : For stacking deck segments.

Reinforcement Yard : For fabrication of reinforcement of all structural elements

like pile, pile cap, pier, precast segment, etc.

Casting, Curing & : For casting, curing & stacking of Parapet, Retaining

Stacking Bay wall & Kerbs.

Fabrication workshop: For fabrication of structural steel for shuttering,

supportive elements & temporary works.

Mechanical workshop : For fabrication of tie rod

CLASSIFICATION OF SEGMENTS

No TypeSegment

widthLocation & Function

1

End Diaphragm (ED) 1.45 ED rest on Abutment. It also has a downstand that enables it to sit on bearings. It has a wall ... It houses coupler cones for pre- stressing cables which are locked here.

2Adjacent to End Diaphragm

(EDA)2.095

It is located adjacent to ED segment.

3 Internal Diaphragm (ID)

2ID segment rest on all the piers except

expansion piers.

4Standard Segment(SS) 2.725 There are 3 nos. SS in the middle of

every span.

5Coupling segment stressing

end (CSS)2.917 CSS segment last segment of

intermediate span which has stressing

6Coupling segment coupling

end (CSC)2.917 CSC Segment is starting segment of

next span

SEGMENT ERECTION There are 3 types of spans to be erected i.e.:

• Type A-Beginning span of each bridge unit,

• Type B-Internal spans,

• Type C- End of each unit.

Type A has 13 segments to be erected with an End diaphragm at the start of

the span. And a CSS segment at the end of the span.

Type B Span start with CSC segment & end with CSS segment.

Type C Span start with CSC segment & end with ED segment.

PLAN SHOWING DIFFERENT TYPES OF SEGMENT WITH THERE LOCATION IN SPAN “A” TYPE.

For erection of 16.4 m wide segment involves following activities

1. Survey and Barricading

2. Erection of EOT

3. Fabrication and erection of staging

4. Erect sliding trolley with jack arrangement

5. Launch precast segments

6. Temporary pre stressing of segments

7. Permanent pre stressing

MAJOR EQUIPMENTS DEPLOYED

1) EOT 60T Capacity - 1 No.

2) EOT 120 T capacity - 1 No.

3) Service crane PH 320 - 2 No

4) JCB Excavator -

2 Nos.

5) Trailer of 40 T capacity - 3 No.

6) Trailer of 100 T capacity -1 No.

Labour required for segment erection including staging& gluing :

• Welder = 01• Grinder = 01• Gas cutter = 01• Skilled labour = 17• Unskilled labour = 10

TOTAL NO. = 30

Technical detailsCapacity of horizontal hydraulic jacks = 50TCapacity of screw jacks = 100TCapacity of one HT strands = 25T Stress induced in each strands = 25.26 Kg/cm2Total stress induced in nineteen strands = 480 Kg/cm2Total elongation of HT cables = 265mmDiameter of one stand = 15.7mm Diameter of one duct = 110mmGluing material used = Sikadur (Component A & B)Quantity of gluing material required per joint = 70 kgWastage of gluing material per joint = 7 kgLoad carrying capacity of Bearing plate = 800TGrouting pressure = 5 Kg/cm2

Properties of gluing material given below

Gluing details

Segment Gluing

Bearing Gluing

Setting time 45 Min. 1hr.

Strength 100 Mpa in 24hrs.

45 Mpa in 24hrs.

Mfg. by SIKA (Goa) Ltd. SIKA (Goa) Ltd.

Following were the main reasons to delay in the completion of project Land acquisition problem

Improper matching of segment

Delay in decision making

Labour strike

Delay in approval of drawings from consultant

Delay in diversion of utilities

CONCLUSION

After studying detail procedure segmental construction that segmental bridges posses following advantages

Rapid erection of superstructure.

High quality & high strength of concrete can be achieved.

Whenever we need to allow traffic underneath even during construction.

The structural geometry may be adopted to any horizontal or vertical curvature or any roadway super-elevation.

Concrete shrinkage & creep substantially reduced.

Segmental construction relatively insensitive to weather condition.

Enhanced durability of bridge.

Segmental bridge reveals following disadvantages

Need for higher level of technology in design

Necessity for a high degree of dimensional control.

The possible solution to the problems discussed in the case study can be enlisted as follows:

Perfect matching of segment at site can be achieved by considering vertical &

horizontal alignment of bridge profile at the time of segment casting.

Whenever the segments are not matched properly considerable time is lost in

chipping out the segment faces. Hence the segment casting should be done

accurately in accordance with drawings.

Thank You