Geometrische Strukturanalyse von Glasfasern in Textilbeton: Fid-Bau Portal

Geometrische Strukturanalyse von Glasfasern in Textilbeton

Focke, Inga

This thesis shows a method to analyse places and bond of glass fibre reinforced concrete. Due to its very low ductility, concrete fails rapidly under tensile load. Reinforcements can increase the stability of concrete with respect to tensile loads by absorbing these loads through the bonds at areas where the concrete fails and thus preparing the building element. The quantitative bond is a measure for the transfer of tensile loads and therefore also an indirect measure for the stability of the entire building element. In most cases concrete is reinforced with steel. Steel is very expensive and corrodes because of environment conditions, an alternative reinforcement is considered which is analysed in a special research field. Textile reinforced concrete, in which the reinforcement consists of long glass fibres, is a new composite material for which this bond is not yet known. Preliminary tests have shown that non-destructive bond analyses are not feasible with the required accuracy and level of detail. This thesis presents a method for location- and bond analyses of textile reinforcement. The analyses are based on scanning electron microscopy images of successive cross-sections of textile reinforced concrete. Using image analysis techniques, the positions of the fibres are extracted and the bonds between the reinforcements and the concrete matrix axe determined geometrically. After correcting for the relative orientations of the cross-sections, the components of the reinforcements are assembled to a three-dimensional model of the reinforcement. The fibres are then approximated by various functions and the results discussed to recap the trajectories of the fibres in the specimen. In addition to the position and trajectory of the reinforcements, the areas of bond are also evaluated qualitatively, extrapolated along the fibres and displayed. The results obtained through this analysis provide a basis for subsequent models for the characterization of textile reinforced concrete which are needed to explain observations from experiments on the reaction of textile reinforced concrete under tensile and bending stress. Attention is paid specifically to the correct mapping of the fibres between the cross-sections. The analysis uses classical approaches from photogrammetric and alignment theory and is performed exemplarily. This method can be transferred to other samples without modification.