Bärförmåga för betongkonstruktioner under nedbrytningsprocess - Slutrapport

Rapport, 2004

It is important to be able to calculate how the load-carrying capacity of concrete structures is affected by environmental impacts, not only for assessment of existing structures, but also for design of new constructions. Corrosion of the reinforcement is one of the most important factors that limits the life time of reinforced concrete structures. When reinforcement corrodes, its volume increases, which in turn causes splitting forces on the surrounding concrete. This can lead to splitting cracks along the reinforcement bar, which has a strong effect on the bond between the reinforcement and the concrete. The aim with this project was to develop a method to analyse how the load-carrying capacity of concrete structures are affected during their life time, in varying environments. A general model describing the bond, with the effect of corrosion included, was developed and implemented in a commercial finite element program. Furthermore, available models describing shrinkage, creep, and development of strength and stiffness of the concrete were used. The models were used in analyses of several test series found in the literature. A good agreement was found. Thereafter, an overview for different cases was compiled. Furthermore, analyses of how large corrosion penetration that is needed to crack the cover depending on concrete quality, cover, and diameter of the reinforcement bar were carried out, and compiled in a diagram. These are the main results from the project: · A model that, through detailed 3D-analyses, makes it possible to describe the influence of corrosion on deformations and load-carrying capacity. · An understanding of the problem – described in an overview. · A diagram describing how large corrosion penetration that will crack the cover depending on concrete quality, cover and diameter of the reinforcement bar. Results from the project have been published in several scientific papers, conference papers and reports, and also in an article in the magazine ”Bygg & teknik”. A complete list of publications is included in this report.