1. Zur Modellierung des Zugtragverhaltens von textilbewehrtem Beton
- Author
-
Bruckermann, Oliver and Hegger, Josef
- Subjects
reinforcement ,Finite-Elemente-Methode ,Ingenieurwissenschaften ,Textilbeton ,fabric ,Bewehrung ,Modellierung ,TRC ,AR-Glas ,ddc:620 ,AR-glass ,Carbon ,Gelege - Abstract
This thesis has been written within the scope of the project D3 "Simulation of textile reinforced elements" which is part of the collaborative reserarch centre SFB 532 "Textile Reinforeced Concrete – Basics for the development of a novel technology". It is a contribution to the multi-scale (micro, meso, macro) modelling approach for Textile Reinforced Concrete that had been developed within the SFB 532. In this document several models for TRC on the meso scale are presented. Thereby the textile reinforcement which consists of several hundreds of filaments is represented by two groups of filaments, namely inner (core) filaments and outer (sleeve) filaments. This way the models provide enough flexibility for a qualitative description of the effects resulting from the decrease of bond quality from the perimenter to the core of the rovings. In the case of uniaxial tensile forces in the direction of the reinforcement the load bearing behaviour is simulated by the one-dimensional Two-Subroving-Model. The relative slip between the filaments and the concrete matrix is modelled explicitly. The properties of the bond interfaces are described by bond stress-slip relationships, which had been obtained from single filament pull-out-tests in the project D2 of the SFB 532. The behaviour of the Two-Subroving-Model is analysed by means of an extensive parametric study within which the properties of the concrete matrix, the bond interface and the textile are varied. Exemplarily, the model parameters are calibrated to reflect selected tensile tests with AR-glass and carbon reinforcements. The model is capable of accurately simulating the stress-strain relationships as well as the multiple cracking process of these specimen. Special effects occuring at the transition from the measurement and the load application zones which are of importance for the ultimate load are elucidated in detail. Using the same principles the macro-element fe_q4_tex2 for the 2D plain-stress state is developed. Additional effects which occur at the cracks when the textile is loaded at an angle are described and incorporated in the model. Thereby the interaction of the crack state and the local damage of the textile is of major importance. The 2D model incorporates a number of parameters relating to the individual mechanical phenomena, the effect of which is demonstrated by means of parametric studies. However, to determine actual values of these parameters micro-level anaysis is required. In order to allow rather coarse FE meshes a further 2D model (mdm-tex) is developed which is based on an implicit model of the bond. In this case a single element is sufficient to model a constant stress state. The results of the two models fe_q4_tex2 and mdm-tex are very similar except for "disturbance zones" at the edges of specimens that can only be simulated using an explicit bond model. Finally, a reasonable (but not yet unequivocal) combination of parameters is given leading to a good agreement between the simulation and tensile tests with sloped reinforcement.
- Published
- 2007