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Utveckling av bytesmetod för järnvägsbroar: Fritt upplagda 20-40 meter
2013 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A well performing infrastructure is essential for the society to function properly and among these infrastructure assets, bridges have a huge part. The nature is full of obstacles that roads and railways need to get past. There are bridges in different materials that have different durability and many different types of load carrying structures but all of them have one thing in common. They all wear down and at some point need to be replaced, either by a new superstructure or a complete new bridge. On some types of bridges, it is not possible to replace the superstructure and then another approach than superstructure replacement is needed. A bridge type that on the other hand suits this type of replacement is the simply supported, one span bridge. It is about these superstructure replacements, with span from 20 to 40 meters this thesis is about. The aim for this thesis is to develop new replacement methods to use in cases where the methods normally used today does not fulfill the requirements or just cannot be used because of things like span or space needed. Two methods are developed, one connecting the old structure and new replacing superstructure and longitudinal launching. This gets the old superstructure away and the new into position over the supports at the same time. In this way the replacement is done quickly and the old superstructure gets up on the track and directly taken away from site. The other method is using the new replacing structure as a beam and from this beam lifting and turning the old superstructure to get it away from the supports. Then lowering the old superstructure, placing it on a road or the ends of the structure on each side of the abutments and finally the new superstructure is lowered into position and the replacement is finished. Calculations are made for both methods to investigate the possibility to implement them on a real case. The first method struggles with large bending moments, replacing a 30 meter superstructure gives a bending moment around 30 MNm in the connecting beam. This can be reduced a lot with some additional supports but that also complicates the method meaning that the method is more suited for smaller spans and truss-truss replacements. The second method got two different lifting solutions. The first is a little simpler but needs the whole lifting force in one wire. It also creates a shear force on the replacing superstructure that was not there during design of the structure and this might result in an interaction problem when calculating the load capacity of the superstructure. The second lifting solution got an additional beam that divides the lifting force to two points. This reduces the bending moment and shear force acting on the new superstructure during replacement and also removes the interaction problem from the first lifting solution. Replacement method two is suitable to use on a bridge with too big span for a railway bridge carrier.

Place, publisher, year, edition, pages
2013. , 93 p.
Keyword [en]
Keyword [sv]
Teknik, Bro, brobyte, järnvägsbro, bridge replacement, railway bridge
URN: urn:nbn:se:ltu:diva-44954Local ID: 2b1d43f1-5f13-42bc-aa0e-784ea45d7c73OAI: diva2:1018233
External cooperation
Subject / course
Student thesis, at least 30 credits
Educational program
Civil Engineering, master's level
Validerat; 20131126 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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