A Case Study on Balanced Cantilever Bridges – Delhi Metro Phase III Piyush Santhalia – Project Engineer
Case Studies Sl. No
Span Project Arrangement (m)
Client
Contractor
Status
1
34 + 60 + 34
CC28 Delhi Metro – Phase III, Line 7
Delhi Metro
L&T
Completed
2
60 + 60
CC28 Delhi Metro – Phase III, Line 7
L&T
Superstructure partly completed
3
37 + 69 + 67 + 55 + 34
CC26R Delhi Metro – Phase III, Line 7
ITD
Foundation and Substructure completed
Case Studies Sl. No
Span Project Arrangement (m)
Client
Contractor
Status
1
34 + 60 + 34
CC28 Delhi Metro – Phase III, Line 7
Delhi Metro
L&T
Completed
2
60 + 60
CC28 Delhi Metro – Phase III, Line 7
L&T
Superstructure partly completed
3
37 + 69 + 67 + 55 + 34
CC26R Delhi Metro – Phase III, Line 7
ITD
Foundation and Substructure completed
CC28 – Balanced Cantilever Bridge
i) 34 + 60 + 34 m
ii) 60 + 60 m
CC28 – Balanced Cantilever Bridge I. 34 + 60 + 34 m
II. 60 + 60 m
CC28 – Balanced Cantilever Bridge I. 34m + 60m + 34m Structure Type Type : Cast-in-Situ PSC Box Box Girder
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34m Span - General Arrangement
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Cross Sections
Overall Width of Deck = 8.844 m Depth of the Box Girder: Varies from 5m at intermediate Piers to 2.1m at Mid-Span
Area (m2)
8.890
Iyy (m4)
28.79
Area (m2)
4.980
Iyy (m4)
2.63
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Foundation & Sub - structure
Intermediate Piers P122 and P123 are integral Piers. Twin Piers, each leaf of dimension 1000 X 3400 mm Free Bearings at P121 and P124. Circular Piers with 2100 mm diameter Pile Foundation 1000 mm dia. , cast-in-situ bored piles.
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Construction Sequence
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Construction Sequence contd…
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Construction Sequence contd…
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Construction Sequence contd…
Casting of Segment S8 (one just before stitch segment)
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Construction Sequence contd…
Casting of Stitch Segment
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Midas Civil has been used for numerical modelling and Structural Analysis - Super Structure (Box Girder) Piers and Piles have been modelled as Line Element - Pile Cap has been modelled as plate element. - Point Spring Supports to take the effect of soil.
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
- Concrete
Analysis & Design
has been modelled with time dependent properties in Midas Civil
- Creep and Shrinkage and compressive strength gain behaviour has been defined as per CEB-FIP
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
- Internal Prestressing - 19T15 and 12T15 anchorages
Analysis & Design
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Simulation of exact Construction Sequence in Midas. - Able to check stresses at intermediate steps in all construction stages.
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Maximum Stress (Tension) at top Fibre Envelope (during construction)
- Maximum Compression at Top Fibre Envelope (during construction)
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Maximum Tension at Bottom Fibre Envelope (during construction)
- Effect of stressing Tendons one by one
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Results: Stress Check for Service Loads: Normal Case
Stresses at Top Fibre due to Combination G I (N/mm2)
Stresses at Bottom Fibre due to Combination G I (N/mm2)
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Pre-camber: Day of commissioning as the critical day
- Precision: Only 6mm of difference between the theoretical value and the observed value of deflection at the cantilever tips, just before stitching.
CC28 – Balanced Cantilever Bridge I.
34 + 60 + 34
Analysis & Design
- Deformation, including the effect of creep after 120 years
Deformation due to Normal Case – after 120 years (mm)
CC28 – Balanced Cantilever Bridge II. 60m + 60m Structure Type : Cast-in-Situ PSC Box Girder
CC28 – Balanced Cantilever Bridge II. 60 + 60m Span - General Arrangement
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Cross Sections
Overall Width of Deck = 8.844 m Depth of the Box Girder: Varies from 5m at intermediate Piers to 2.868m at Mid-Span
Area (m2)
8.890
Iyy (m4)
28.79
Area (m2)
5.71
Iyy (m4)
5.86
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Foundation & Sub - structure
Intermediate Piers P217 is integral Piers. 2300mm Diameter circular Pier Free Bearings at P216 & P218. Circular Piers with 2100 mm diameter Pile Foundation 1000 mm dia. , cast-in-situ bored piles.
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Midas Civil has been used for numerical modelling and Structural Analysis - Super Structure (Box Girder) Piers and Piles have been modelled as Line Element - Pile Cap has been modelled as plate element. - Point Spring Supports to take the effect of soil.
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Construction Sequence & Analysis
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Construction Sequence contd…
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Construction Sequence contd…
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Construction Sequence contd…
CC28 – Balanced Cantilever Bridge II. 60 + 60m
- Internal Prestressing - 19T15 and 12T15 anchorages
Analysis & Design
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Maximum Stress (Tension) at Top Fibre Envelope (during construction)
- Maximum Compression at Top Fibre Envelope (during construction)
Sign Convention: +ve Value of Stresses denote Tension
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Maximum Tension at Bottom Fibre Envelope (during construction)
- Maximum Compression at Bottom Fibre Envelope (during construction)
Sign Convention: +ve Value of Stresses denote Tension
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Results: Stress Check for Service Loads: Normal Case
Stresses at Top Fibre due to Combination G I (N/mm2)
Stresses at Bottom Fibre due to Combination G I (N/mm2 ) Sign Convention: +ve Value of Stresses denote Tension
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Pre-camber: Day of commissioning as the critical day
CC28 – Balanced Cantilever Bridge II. 60 + 60m
Analysis & Design
- Deformation, including the effect of creep after 120 years
Deformation due to Normal Case – after 120 years (mm)
