2006 iitk-urban transportation-infrastructure
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Transcript of 2006 iitk-urban transportation-infrastructure
Urban Transportation Infrastructure-Construction Techniques
Presented by-
Pravin Kolhe,MTech, Transportation System
Engineering,Department of Civil Engineering,
IIT Kanpur.
Overview of presentation
IntroductionConstraints during constructionPlanning for projectMaterialsTechniques for Urban Transportation Structure
Superstructure Substructure
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1. Introduction
Urban transportation infrastructure involves large scale construction
There are various constraints.Need of innovative techniques for timely
completion.
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2. Constraints during construction Space constraint Time constraint Utilities Environment Aesthetics Safety Economy
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2.1 Space constraint Historical Places Existing structures Minimum
disturbance to traffic
Photo.1. Space constraintPhoto: http://www.civil.skanska.com/skanska/templates/page.asp?id=3359
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2.2 Time constraint
Construction of new infrastructure is normally taken up when existing infrastructure is not sufficient to fulfill the demand.
Urgent need to start and complete the construction During the construction, the existing infrastructure is
strained further. So, timely completion of the project is important.
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2.3 Utilities Infrastructure normally passes through densely
populated area. So, there are some utilities as
Water mains (Underground) Sewer lines (Underground) Telephone lines (underground or overhead) Power supply lines. (overhead)
These utilities should be diverted, which is time consuming and costly affair.
Many times, the utilities are not known till the starting of work.
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2.4 Environment
Air and noise pollutionDue to slow moving vehicular trafficDue to construction activity
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2.5 Aesthetics
Photo 2. Aesthetics of urban transportation infrastructurePPT Downloaded from http://www.pravinkolhe.com/
2.6 Safety
Accidents causes loss ofLifePropertyEnvironment
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3 MaterialsPreferred materials-
BricksStonesTimberMetalsConcreteComposite
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3.1 Bricks
• For small spans• Light Loads
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3.2 Stones
• Old construction material
• For small spans• Time consuming• Light load
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3.3 Timber
• Temporary Bridges• Less span and less load
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3.4 Metal
• Speedy construction
• Large span• Heavy loads
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3.5 Concrete
• Precast• Pre-stressed
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3.6 Composite
Use of metal + Concrete
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4. Techniques for ConstructionElevated structures are divided it to-
SuperstructureSubstructure
Fig. 3. Components of elevated structures
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4.1 Techniques for Superstructure
Techniques-Span-by-span construction with precast girder.Precast post-tensioned segmental techniqueContinuous units on ground supported stagingCentral span by Cantilevering techniqueBalanced cantilevering technique
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4.1.1 Span-by-span construction with precast girdersMost economicalPrestressed girders are
lifted from casting yard and transported to site on trailers
At site they are lifted and placed on pier cap by cranes.
Deck slab is then casted over these girders.
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4.1.2 Precast post tensioned segmental techniqueSimply supported post-tensioned units of 2~3
m with epoxy bonded joints.For standardization of segments, cable profile
is made horizontal in the middle span.
Fig.5. Construction by Precast post-tensioned segmental technique
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4.1.3 Continuous units on ground supported staging
At crossing, central span is more.So prestressed continuous units becomes
obligatory.In such case, central unit can be casted by
staging by diverting traffic
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a) End spans are casted on staging
b) Traffic diverted and central span is casted on staging
c) Open to traffic.
Fig 7. Construction of continuous unit on ground supported staging
4.1.4 Central span by cantilevering techniqueEnd spans are casted on stagingCentral span is casted by cantilevering.When two cantilever meet, the stitch
segment is casted.
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a) End spans are casted on staging
b) Cantilevering construction started from ends
c) Cantilevering construction completed from both ends.
Fig 8. Construction of central span by cantilevering PPT Downloaded from http://www.pravinkolhe.com/
d) Stitch segment is casted
e) Construction completed
Fig 9. Construction of central span by cantilevering PPT Downloaded from http://www.pravinkolhe.com/
4.1.5 Balanced cantilevering technique
Only end portion of end span is casted on staging
Remaining end span and central span is casted by balanced cantilevering.
When two cantilever meet, the stitch segment is casted.
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a) End portion of end spans are casted on staging
b) Cantilevering construction started from ends in both directions
c) Cantilevering construction completed from both ends.Fig 10. Construction by balanced cantilevering
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d) Ground supported staging at end spans
e) Stitch segment is casted
f) Construction completedFig 11. Construction by balanced cantilevering
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Fig. 12. Construction by balanced cantileveringPPT Downloaded from http://www.pravinkolhe.com/
4.2 Techniques for SubstructureTechniques-
Self supporting cutting.Sheet pilesDiaphragm wallSingle cast-in-situ bored pile.Driven casted pileGroup of piles.Well foundation
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4.2.1 Self supporting cutting
For shallow depth and hard soil, soil cutting is possible at self supporting slopes.
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5.2.2 Using sheet pile
For higher depth &/or soft soil sheet pile are preferred.
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4.2.3 Using diaphragm wallFor deep
cutting, diaphragm wall is most useful
These are installed prior to taking up the excavation work.
Generally, it is part of final structure
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4.2.4 Cast-in-situ bored pile150 - 600mm dia to
20m deepAs a rotary auger
causes minimal vibration it is ideal for use next to buildings or underground services without destabilization.
Dewatering techniques can be used if water is present.
Fig 13. Cast-in-situ bored pile
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4.2.5 Driven casted pile150mm - 600mm to
20m deepUsed on soft soils
overlay. Permanently steel
cased piles are driven with an internal drop hammer.
Suitable reinforcement is then added and the casing filled with concrete.
Fig 14. Driven casted pile
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4.2.6 Group of piles Most of pile foundations
consists not of a single pile, but of a group of piles, which act in the double role of reinforcing the soil, and also of carrying the applied load down to deeper, stronger soil strata.
Fig 15. Group of piles
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4.2.7 Well foundation.Used under very
heavy loads to be carried by soft soil.
Fig 16. Well foundation
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Thank you(c) Pravin Kolhe, 2006
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