Assessment of Norwegian Bridges Affected by ASR

The scope, results, and experience from the Norwegian research project MESLA (Management and Extension of Service Life of infrastructures affected by Alkali-silica reactions (ASR) are presented. The main objective of the project is to contribute to an improved system for management of our infrastructure. A major task for the project is to evaluate the effect of compressive stress on the expansion and cracking, creating large degrees of anisotropy. The project has access to many bridges for field survey, monitoring and sampling for laboratory investigations. Based on condition data, structural analyses are carried out for selected bridges, and material models for ASR-affected concrete are developed. One of the monumental bridges considered is the Tromsø bridge (1960), where the ASR-induced expansion and deterioration is leading to closed expansion joints, extensive cracking, column deformations and damaged bearings. The material degradation and the expansion induced moments are of vital importance, and relevant deteriorated structural members are the bridge slab, continuous RC beams, post-tensioned beams and slender columns. The material degradation is mainly mapped by applying the Stiffness Damage Test method (SDT). Despite the ASR-induced damages, the Tromsø bridge has sufficient safety margin against structural failure, even though the need for maintenance is large.