FEM analysis of existing buildings during renovation

Sammanfattning: In this masters thesis the aim was to investigate a part of Sturegallerian in Stockholm to be reconstructed. The reconstruction did implicate that openings were to be established in an already existing masonry wall. Reconstruction of an old masonry building entails certain difficulties due to the lack of knowledge regarding the building methodology of the existing structure. The purpose of the project was to analyze the effects of a desired reconstruction. A further purpose was to identify the effect with a suggested steel amplifier. In addition it was of interest to see how different modeling strategies would effect the results and discuss what modeling strategy that was most preferred for this project. For the project the specific wall structure was established in the finite element method software, named Räumlich Finite Element Method, as well as a model with the reconstructions established. A comparison of the existing structure with the reconstructed leads to a better understanding of the characteristics of the structure and the specific loads acting on the structure. Further, two different modeling strategies were assigned: one with an isotropic material model and the other as an orthotropic. The models were evaluated for the Ultimate Limit State as well as the Serviceability Limit State to verify the critical behaviours. The models were analyzed for the specific limit states: the deformations, internal forces and the axial stresses. Further, the suggested steel amplifiers were implemented in the reconstructed models to be able to analyze the effects. When the steel amplifiers were assigned to the reconstructed models, the same limit states were analyzed for the deformations and for the internal forces. The conclusion of this project was that an orthotropic material model is best suited for masonry structures. The steel amplifiers were implemented in the orthotropic material model and were further analyzed in the Finite Element software. With the steel amplifiers one could see that the deformations decreased and were still lower than the maximum deformation. One could see that the compression stresses within the masonry wall decreased with the implemented steel amplifiers. The utilization ratio for the steel amplifier was established in Colbeam. The result of stresses, deformations, utilization ratio and stresses within the structure resulted in that this type of amplifier was considered as applicable for this project.