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Concrete Cracks in Composite Bridges: A Case Study of the Bothnia Line Railway Bridge over Ångermanälven
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
2012 (English)Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Cracks in the concrete slab of continuous composite bridges are common due to the tensile stresses at the supports. These bridges are allowed to crack as long as the cracking is controlled and not exceeding the design crack width (according to Bro 94 the crack should be injected if they are bigger than 0.2 mm). The Ångermanälven Bridge (railway bridge part of the Bothnia line project) was designed with big edge beams of width 1.2 m, 40 % of the total area of the concrete deck cross-section. During the final inspection cracks larger than the design crack width (0.3 mm according to Bro 94) were observed over the supports.In this thesis the design and the construction procedure of the bridge is studied to clarify the causes of the cracking in the edge beam. The objectives of this thesis were addressed through a literature study of the different types of cracks and the Swedish bridge codes. The expected crack width was calculate according to the same code, using a 2-D FEM model for the moment calculation, and compared with the crack width measured at the bridge.The result of the calculations shows that tensile stress due to ballast and only restraining moment due to shrinkage is not big enough to cause the measured crack width. Shrinkage force and temperature variation effects may have contributed to the concrete cracking in the edge beams. The large cross-section area of the edge beams indicates that it should be designed as part of the slab, taking that into consideration, 1.1 % reinforcement ratio in the edge beams is believed to limit the crack width to the code limits (0.3 mm).

Place, publisher, year, edition, pages
Trita-BKN-Examensarbete, ISSN 1103-4297 ; 352
Keyword [en]
Composite Bridge, Cracks, Edge Beam, Bothnia Line, Reinforcement for Crack Control
National Category
Infrastructure Engineering Civil Engineering
URN: urn:nbn:se:kth:diva-100831OAI: diva2:545298
Subject / course
Structural Design and Bridges
Educational program
Master of Science in Engineering - Urban Management
Available from: 2012-09-10 Created: 2012-08-19 Last updated: 2012-09-10Bibliographically approved

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