Shree Swami Atmanand Saraswati Institute of Technology

Erection of

Steel Girder and Steel Truss Bridges

Prepared By :-Balar Piyush 110763106063Vekariya Sandeep R. 120763106001Kakadiya Gaurang A. 120763106002Balar Jigar H. 120763106003

Guided By :-Prof. A.P. SatasiaProf. P. V. TrivediProf. R. R.Tripathi

Railway Bridge & Tunnel Engineering

†Contents

Introduction to Steel Girder Bridges

Erection of Steel Girder Bridges

Methods

Erection of Steel Truss Bridges

References

† Introduction to Steel Bridges

The steel girder bridge is a structure in which a floor system and roadway, concrete or timber, is supported by girders, usually rolled section beams which are plain or encased in concrete

These are normally used for railways and rarely for highways

Following data should be collected prior to the erection of these bridges: Time estimate for the construction of a bridge Condition of proper equipment and machinery Condition of bridge site Facility for transportation and storage of materials at bridge site Necessary supporting system for superstructure Availability of steel structures Width and depth of flow in the river Height of bridge from river bed

Methods for erection of steel bridges

Erection by Lifting Method

Erection by Staging

Erection by Floating

Erection by Rolling

Erection by Launching of single girder span

† ERECTION OF STEEL GIRDER BRIDGES

† Erection of Steel Bridges Methods

Erection by Lifting Method Steel girders upto span of 30 m can be

easily erected if the height is 5 to 6 m This method is suitable for rivers which

are dry for the most part of the year A platform is created by filling earth to

sufficient height and levelled

Girders are assembled on the river bed and field riveted/bolted They are lifted into position by means of stiff-leg derrick cranes or

ordinary rope worked from anchored crab winches The flooring and the bracings are then field connected to the girders

placed in position

Erection By Lifting

SOLNA BRIDGE, STOCHOLM, SWEDEN

† Erection of Steel Bridges

Methods

Erection by Staging: Favourable conditions:

Depth of water in the river is shallow Height of superstructure above the river should not be

excessive Span should be simply supported

Staging consists of trestle frames which may be of steel or timber

Iron staging is lighter than timber staging and, therefore, can be easily transported

Staging is suitably designed and after it is constructed, the erection of steel girders is commenced on the staging

Erection by

Staging

† Erection of Steel Bridges

Methods

Erection by Floating: Favourable conditions for this method are:

Depth of water in the river is moreFloating barges/pontoons are used to carry the steel girdersBridge is assembled on the barges and is floated into position

when complete.

The barges are so positioned that span is over the final alignment, when the jacks are used to lower the span on the bearings.

Finally the barges are sunk by flooding the tanks

Coleman Bridge, York River in Yorktown

† Erection of Steel Bridges

Methods Erection by Rolling:

This method is adopted for erection of continuous girders on deep gorges

First span near the abutment is erected by any one method of erection

Girders of the first span are brought to the required position by rolling them from the abutment through the erected span

This method is also known as the Incremental Launching Method and has become very popular for the concrete girders

Second span is cantilevered when it projects from the erected span and acquires counter weight for its stability

This counter weight is provided by the successive span connected to it and its back

† Erection of Steel Bridges

Erection by Launching of single girder span

Each girder is first assembled on a track of rollers behind one of the abutments and is cantilevered as far as possible over the span.

The lifting blocks are then fastened to the outmost point of the girder and the heavy wire is coupled to the winch.

Rear end of the girder is tied to another winch which is released slowly so that sudden forward motion may no take place.

Erection by Launching of

Kurilpa Bridge, Brisbane, Australia

† Erection of Steel Truss Bridges

These bridges are erected with the help of a stiff derrick traveller and two false work bents

Erection procedure may be described in four stages:

Second stage Move traveller (crane)

to B Erect false work bent T2

Assemble the section BC

First stage Erect false work bent T1

Assemble the section AB

† Erection of Steel Truss Bridges

Third stage Move traveller to C Remove false work bent T1 from

B and erect it at D Assemble the section CD

Fourth stage Move traveller (crane) to D Assemble the section DE Release the false work bent T1 and

T2

† References

ftp://ftp.mdt.mt.gov/research/LIBRARY/NSBASBEGS-1-OL-STEEL_BRIDGE-AASHTO.PDF

http://www.deldot.gov/archaeology/historic_pres/hist_bridge_survey/pdf/steel.pdf

http://www.kwhconstructors.com/img/gallery/williamr.bennettbridge/wrb_bridge5.JPG

THANKYOU