REDOGÖRELSE FÖR SPRICKARMERING FÖR KONSEKVENT DRAGNA BETONGPLATTOR PÅ MARK : Analys av skillnader mellan BBK 04 och Eurokod 2 med tillämpning av svenskt och danskt nationellt annex

In this diploma work the approach of determining the required amount of reinforcement in slabs exposed to pure tension is processed, on behalf of Ramböll Uppsala. It is a well-known problem in the industry that there are uncertainties in the determining of the amount of crack reinforcement, especially for structures exposed to pure tension. Cracking caused during the time of dehydration in concrete slabs is the most common defect according to statistics made by CBI[1], which provides numbers as high as 35 % of all the defects caused on slabs are generated by cracks. Comparisons between Sweden's former national standard BBK 04, Building Regulations for concrete structures due to restrained forces of shrinkage, and the current European standard Eurocode 2 are carried out through theoretical studies and concludes with several examples of calculations. Rigorous calculations of both standards, BBK 04 and Eurocode 2 with application of the national annex in Sweden and Denmark are performed. Besides the comparison of the standards there’s also an alternative method, Annex D reported in Concrete Report 13 which is based on a Danish model and a table method reported in Eurocode 2, that’s been compared to. It’s a simplified calculation formula which gives less the amount of reinforcement in fulfilling a crack width requirement if using the Danish value in comparison with the Swedish. This has been carried out to provide a deeper understanding of how to proceed in order to achieve a more optimized result than appears by calculation performed today. The result of this work has resulted in the development of a calculation document in excel, used for when determining the minimum amount of reinforcement for apportion of the cracks in slabs exposed to pure tension with respect to the current state regulations and when fulfilling a crack width requirement. [1] The Swedish institute of cement and concret