Kapasitetsberegning og tilstandsvurdering av korrosjonsskadet betongbru: Lundevann bru
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This master thesis deal with calculation and condition assessment of Lundevann bridge, which is a corrosion-damaged bridge with decks of pretensioned concrete beams, spanning between transversal beams. The transversal beams are connected to piles which transfers the loads to the ground. The thesis presents the theoretical basis that underlies the calculations, as well as literature on the concrete's decomposition mechanisms. Loads and load combinations are calculated by the Norwegian Road Safety Authority's Handbook R412 for bridge classification, and the capacity checks are performed according to NS-EN 1992-1-1 (Eurocode 2). The bridge is modeled in Autodesk Robot Structural Analysis Professional 2017, and used for analysis of dimensional loads. Capacity control of the constructive parts of the bridges is performed for its undamaged condition according to current regulations. A visual inspection and a special inspection have been carried out with extraction of new concrete samples, which together with previous inspections forms the basis for an assessment of the current damage level on the bridge. RCT and ISE methods have been carried out in order to analyze the concrete samples, and perform chloride measurements. New samples that correspond to previous withdrawal points are compared to evaluate the development of chloride content in the concrete elements. Based on capacity checks and damage assessment calculations have been made in order to estimate the consequences the damage will have for the load bearing capacity of Lundevann bridge. This has been done by examining the consequences of loss of concrete cover in the pressure zone, and by reducing the reinforcement area. Capacity controls of the bridge in undamaged condition indicated that the bridge elements have sufficient load bearing capacity. The transversal beam in axis 9 has, however, exceeded the bending moment capacity in the longitudinal direction of the bridge, and attention should be paid. The extent of damage due to corroded reinforcement is greatest for the transversal beams of axis 2-8, and extensive corrosion of the tension reinforcement above the supports (piles) may be critical to the beams bending capacity. Since the damage level is difficult to determine exactly without direct measurements, the need of remediation measures on the transversal beams seems to be large.
Masteroppgave - Universitetet i Agder. Fakultet for teknologi og realfag. Institutt for ingeniørvitenskap.