Kiruna bridge (case study)
Object description
This 122 meter long bridge with five continuous spans was built in 1959 along highway E10 near Kiruna in northern Sweden. The superstructure consist of three prestessed concrete girders with a reinforced concrete slab on top. The prestressing system is post-tensioned system with four to six tendons parabolically aligned in each girder. One tendon is composed of 32 strands with diameter 6 mm.
Object analysis
This study presents a framework for successively improved structural analysis and verification. For structural analysis the initial level comprises beam, frame, handbook or simple FE models combined with local resistance models. The most enhanced level is a full non-linear FE-analysis reflecting all possible failure modes. The verification format is divided into partial safety factor format, global resistance safety factor format and full probabilistic analysis. To include bridge specific information is also treated. For the case study bride, the difference in permitted axel load was ten times higher for the most enhanced analysis compared with the initial one.
Object state
Measurements of the in situ concrete strength and modulus of elasticity as well as tensile strength, yield strength and strain at peak stress for reinforcement and strands were carried out. 25 concrete cores and 40 steel samples were collected and the data was used to update the models in a non-bayesian way.
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Documents
This case study was contributed by Frida Liljefors of Norwegian University Of Science And Technology. Last edited by technical staff.