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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