Steel Composite Bridge Construction R1

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Composite construction in Bridge Deck systemsA Solution in City Environment for Speedy

Construction with Industrialized Full Length Prefabrication

By

S. P. Khedkar , Kishore Saxena - XCC Engineers & Planners

Presentation in CEMCON 2014 National Conference on "Composite Construction & Modern Concrete“ Pune 12th Sept 2014

Typical Site Conditions and Basic Requirements in Construction of Urban Flyovers.

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Flyovers have become a basic need of any busy and growing city to avoid traffic congestion and smooth traffic flow at busy intersections.

They Have to be constructed on the busy roads and in overcrowded environment.

Causing Minimal disturbance to traffic

Ensuring Safety of the citizens.



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During tight construction schedule, - Basic Demand

Without Closure of existing Roads.

In Restricted time of small working windows during late night , especially for superstructure erection.



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Normal Methods of Construction of Urban Flyovers

• Precast Segmental Construction

• Precast Full Length PSC girders with Cast in Situ Deck

• Prefabricated Structural Steel Girders with Cast in Situ RCC Deck slab –Normally Not preferred due to higher cost and maintenance issues.


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• Use of Precast or Prefabricated components for superstructure help in reduction of construction time, as superstructure components can be kept ready elsewhere, when construction of foundations and substructure is in progress.

Use of Precast / Prefabricated Components for Construction of Urban Flyovers.


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• Erection of such components can be planned during night hours, when the traffic is minimal; thus causing least hardships to the general public

• Many flyovers have been constructed in our country using full length precast prestressed girders, and cast in situ deck slab.



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• Flyovers with full length prefabricated girders in structural steel and composite RCC deck slab are very few.

• This paper discusses use of such structural system for congested cities.



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Urban Flyovers in Precast Prestressed Concrete : Salient Features

• Typical spans Range between 20 to 30m. Precast prestressed girders can be transported from casting yard and erected at site. In situ deck slab can be cast on the erected girders.

• Over intersections the span length is dictated by the site conditions. The obligatory spans are much longer , ranging between 40 to 50 m.

• If full length precast girders with deck slab are used for typical spans, Obligatory spans need different structural system like cast in situ box girder; as transportation and erection of precast girders of longer length is not feasible in urban conditions .


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Urban Flyovers in Prefabricated Structural Steel Girders: Salient Features

• Typical spans Range between 20 to 30m. Prefabricated girders can be transported from fabrication yard and erected at site. In situ deck slab can be cast on the erected girders.

• Over intersections the span length is dictated by the site conditions. The obligatory spans are much longer , ranging between 40 to 50 m.

• Girders for obligatory spans can be fabricated in units of shorter lengths suitable for transportation and erected on staging. The individual units can be spliced at site.

• Thus Obligatory spans need not have different structural system like box girder. All the spans can have uniform appearance.

Different Deck Systems for Structural Steel Girders with Composite Deck Slab


Presentation in CEMCON 2014 National Conference on "Composite Construction &

Modern Concrete“ Pune 12th Sept 201412

1. Plate Girders with Cross Diaphragms and Cast in Situ Deck Slab

2. All components of the steel concrete composite deck with shear connectors and the Composite action is explained in the sketch.




Examples of Plate Girders with Cross diaphragms and Cast in Situ Deck Slab




Examples of Fabricated Plate Girders and Erected Girders at site




Example of Full Length Steel Girder being Transported to site




Examples of Plate Girders with Cross diaphragms and Cast in Situ Deck Slab a Flyover in Kolkata



Examples of Box Girders with and Cast in Situ Deck Slab




Example of Box Girders with and Cast in Situ Deck Slab- Flyover Bridge at Kolkata – Obligatory Span




Example of Innovative Composite Steel Truss with Cast in Situ Deck Slab


Comparison between Precast Prestressed Girders and Steel Composite Girders


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Precast Prestressed Girders: Prefabricated Steel Girders:

Shape: I Girder , Box Girders, Multiple Box Girders

Shape: I Girder , Box Girders, Multiple Box Girders

Suitable span length for Urban flyovers : 20 to 30 m

Suitable span length for Urban flyovers : 20 to 30 m, or longer spans with In Situ splicing.

Weight of girders: Range between 40 to 90 T. Normally not precast in shorter lengths, although Spliced girders have been adopted in some flyovers.

Weight of girders: Range between 20 to 40 T. Individual units of shorter lengths can be used to restrict the length and weight for transportation and erection.

Need Special setup of casting yard for precasting girders.

Need Special setup of fabrication yard for prefabrication of girders. However, girders can also be fabricated in workshops, when special setup is not needed.


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Precast Prestressed Girders: Prefabricated Steel Girders:Need heavier cranes and erection gantries for erection at site.

Need cranes and erection gantries of relatively smaller capacity for erection at site.

Appearance: Generally considered as acceptable, although tends to gather dust on bottom bulbs and spoil appearance.

Appearance: May not be considered as acceptable, due to stiffeners and cross diaphragms.

Appearance can be improved by adopting Trapezoidal girders, which do not accumulate dust.

Appearance can be improved by adopting multiple box girders, and providing stiffeners inside the box. Cross diaphragms can also be U shaped for uniform appearance.

Maintenance: Normally the girders do not need maintenance.

Maintenance: The girders and cross diaphragms need regular maintenance in the form of painting to avoid corrosion.


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Discussion and Conclusion

1. Use of Prefabricated Steel Girders is relatively rare in India due to Cost and Maintenance considerations. However , the system has following advantages:

a. Weight of girders is much less, and needs lower capacity trailers for transportation, and lighter cranes for handling and erection.

b. Can be advantageous for construction on narrow roads, where large trailers and cranes can not be deployed.


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Discussion and Conclusion

c. Appearance of girders may not be acceptable due to skeletal nature, visible stiffeners and bracings. But can be improved by adopting multiple box girders and provision of stiffeners entirely inside box girders.

d. Need of Regular Maintenance may be an important consideration against use of Steel girders. However, Multiple box girders, if sealed from ends, need painting only from outside, on plain surfaces, and can be done with relative ease.


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Composite construction in Bridge Deck systemsA Solution for Urban Flyovers.

The Authors have made an attempt to present a

relatively rare structural system in India viz. Composite Steel Girders for Urban flyovers.

The authors are grateful to CEMCON 2014 for accepting their paper and extending invitation to present the same in the National Conference on “Composite Construction and Modern Concrete”.

Thank You.

Steel Composite Bridge Construction R1

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