The extended finite element method (X-FEM) is becoming increasingly popular due to its ability to... more The extended finite element method (X-FEM) is becoming increasingly popular due to its ability to dynamically embed discontinuities into the approximated displacement field. By a local enrichment of the already existing shape functions an expensive remeshing in every step of the crack propagation algorithm can be avoided. In the case of quasibrittle materials with a finite length of the fracture process zone it is reasonable to adjust the mesh density according to the characteristic length near the crack tip while keeping the mesh coarse in uncritical regions. Therefore we combine the dynamic mesh modifications (1) to enrich (X-FEM) the shape functions in order to introduce cracks and (2) to refine the mesh for an appropriate resolution of the fracture process zone by the means of hierarchical h-adaptivity. The validation of the algorithm is done with the help of experimentally obtained deformation field history measured during the loading process. The measurements are performed usi...
The paper presents the study of spalling effect occurring under tensile loading in thin-walled TR... more The paper presents the study of spalling effect occurring under tensile loading in thin-walled TRC specimens. The experimentally observed failure patterns are first classified and the performed experiment design is explained and discussed. A parameter study of spalling effect with varied thickness of concrete cover and reinforcement configurations including both the textile fabrics and the yarns provided the basis for numerical analysis of the effect. The applied numerical model was designed in order to capture the initiation and propagation of longitudinal cracks leading to the separation of concrete blocks from the textile fabrics. A meso-scopic material resolution in a single crack bridge is used for the simulation exploiting the periodic structure of the crack bridges both in the lateral and in the longitudinal direction of the TRC specimens. The matrix was modeled using an anisotropic damage model falling in the microplane-category of material models. The bond between yarn and ...
Zusammenfassung: Als Großdemonstrator des Sonderforschungsbereichs 532 soll auf dem Gelände der F... more Zusammenfassung: Als Großdemonstrator des Sonderforschungsbereichs 532 soll auf dem Gelände der Fakultät für Bauingenieurwesen der RWTH Aachen ein Ausstellungspavillon mit einer Dachkonstruktion aus Textilbeton errichtet wer-den. Der Beitrag zeigt die automatisierte Bemessung dieser komplexen Trags-truktur mit Hilfe eines hierfür entwickelten numerischen Bemessungsstools. Die Auswertung erfolgt für alle Lastfallkombinationen nach DIN 1055-100 und unter Berücksichtigung der Reduktion der Tragfähigkeit der textilen Bewehrung infol-ge einer Umlenkung im Riss sowie einer Erhöhung der aufnehmbaren Tex-tilspannungen infolge Biegebeanspruchung. Zur Ermittlung der Tragfähigkeit der Textilbetonschale wurden am Institut für Massivbau Dehnkörper-und Biegever-suche durchgeführt, die in Bewehrungsgrad und Dicke dem realen Bauwerk am Schalenrand entsprachen. Summary: Within the collaborate research center 532 at RWTH Aachen Univer-sity the construction of an exposition hall with a double-curved r...
The presented material model reproduces the anisotropic characteristics of textile reinforced con... more The presented material model reproduces the anisotropic characteristics of textile reinforced concrete in a smeared manner. This includes both the initial anisotropy introduced by the textile reinforcement, as well as the anisotropic damage evolution reflecting fine patterns of crack bridges. The model is based on the microplane approach. The direction-dependent representation of the material structure into oriented microplanes provides a flexible way to introduce the initial anisotropy. The microplanes oriented in a yarn direction are associated with modified damage laws that reflect the tension-stiffening effect due to the multiple cracking of the matrix along the yarn.
The paper presents a meso-scopic modeling framework for the simulation of three-phase composite c... more The paper presents a meso-scopic modeling framework for the simulation of three-phase composite consisting of a brittle cementitious matrix and reinforcing AR-glass yarns impregnated with epoxy resin. The construction of the model is closely related to the experimental program covering both the meso-scale test (yarn tensile test and double sided pull-out test) and the macro-scale test in the form of tensile test on the textile reinforced concrete specimen. The predictions obtained using the model are validated using a-posteriori performed experiments.
Based on the German Code E DIN 19700 (2001) the Ruhrverband Essen in collaboration with RWTH Aach... more Based on the German Code E DIN 19700 (2001) the Ruhrverband Essen in collaboration with RWTH Aachen and Bauhaus University Weimar recently performed safety assessments of its barrages. In particular, the seismic slope stability of the rockfill dams and the hydro-fracturing problem of masonry dams have been analyzed in detail. Because of the importance of the structures and the potential damage involved in the collapse of a dam, the time-stepping algorithm was used in the seismic analysis of the slope stability instead of the simplified quasi- static Krey/Bishop method. In addition to the earthquakes specified by the German code, measured accelera- tion characteristics of the Roermond earthquake were applied. The safety assessment has been performed by postprocessing of the computed stress field histories to obtain the corresponding slope stability characteristics (Meskouris et al. 1999a, b). For the masonry dams the hydro-fracturing problem, which may be caused by the water penetrat...
This paper describes concepts used in the development of a technical information system (TIS) for... more This paper describes concepts used in the development of a technical information system (TIS) for supporting collaborative material research. The system has been set up to support the development of textile-reinforced concrete (TRC) by applying the modern theoretical concepts of software and database engineering to integrate the available open source tools in an effective way. The system works as a database powered internet server with a transparent definition of the product and process model.
In this paper the development of a consistent material model for textile reinforced concrete is p... more In this paper the development of a consistent material model for textile reinforced concrete is presented. Load carrying and failure mechanisms at the micro, meso and macro scales are described and models with the focus on the specified scales are introduced. The models currently being developed in the framework of the collaborative research center are classified and evaluated with respect to the failure mechanisms being captured. The micromechanical modeling of the yarn and bonding behavior is discussed in detail and the correspondence with the experiments focused on the selected failure and interaction mechanisms is shown. The example of modeling the bond layer demonstrates the application of the presented strategy.
The extended finite element method (X-FEM) is becoming increasingly popular due to its ability to... more The extended finite element method (X-FEM) is becoming increasingly popular due to its ability to dynamically embed discontinuities into the approximated displacement field. By a local enrichment of the already existing shape functions an expensive remeshing in every step of the crack propagation algorithm can be avoided. In the case of quasibrittle materials with a finite length of the fracture process zone it is reasonable to adjust the mesh density according to the characteristic length near the crack tip while keeping the mesh coarse in uncritical regions. Therefore we combine the dynamic mesh modifications (1) to enrich (X-FEM) the shape functions in order to introduce cracks and (2) to refine the mesh for an appropriate resolution of the fracture process zone by the means of hierarchical h-adaptivity. The validation of the algorithm is done with the help of experimentally obtained deformation field history measured during the loading process. The measurements are performed usi...
The paper presents the study of spalling effect occurring under tensile loading in thin-walled TR... more The paper presents the study of spalling effect occurring under tensile loading in thin-walled TRC specimens. The experimentally observed failure patterns are first classified and the performed experiment design is explained and discussed. A parameter study of spalling effect with varied thickness of concrete cover and reinforcement configurations including both the textile fabrics and the yarns provided the basis for numerical analysis of the effect. The applied numerical model was designed in order to capture the initiation and propagation of longitudinal cracks leading to the separation of concrete blocks from the textile fabrics. A meso-scopic material resolution in a single crack bridge is used for the simulation exploiting the periodic structure of the crack bridges both in the lateral and in the longitudinal direction of the TRC specimens. The matrix was modeled using an anisotropic damage model falling in the microplane-category of material models. The bond between yarn and ...
Zusammenfassung: Als Großdemonstrator des Sonderforschungsbereichs 532 soll auf dem Gelände der F... more Zusammenfassung: Als Großdemonstrator des Sonderforschungsbereichs 532 soll auf dem Gelände der Fakultät für Bauingenieurwesen der RWTH Aachen ein Ausstellungspavillon mit einer Dachkonstruktion aus Textilbeton errichtet wer-den. Der Beitrag zeigt die automatisierte Bemessung dieser komplexen Trags-truktur mit Hilfe eines hierfür entwickelten numerischen Bemessungsstools. Die Auswertung erfolgt für alle Lastfallkombinationen nach DIN 1055-100 und unter Berücksichtigung der Reduktion der Tragfähigkeit der textilen Bewehrung infol-ge einer Umlenkung im Riss sowie einer Erhöhung der aufnehmbaren Tex-tilspannungen infolge Biegebeanspruchung. Zur Ermittlung der Tragfähigkeit der Textilbetonschale wurden am Institut für Massivbau Dehnkörper-und Biegever-suche durchgeführt, die in Bewehrungsgrad und Dicke dem realen Bauwerk am Schalenrand entsprachen. Summary: Within the collaborate research center 532 at RWTH Aachen Univer-sity the construction of an exposition hall with a double-curved r...
The presented material model reproduces the anisotropic characteristics of textile reinforced con... more The presented material model reproduces the anisotropic characteristics of textile reinforced concrete in a smeared manner. This includes both the initial anisotropy introduced by the textile reinforcement, as well as the anisotropic damage evolution reflecting fine patterns of crack bridges. The model is based on the microplane approach. The direction-dependent representation of the material structure into oriented microplanes provides a flexible way to introduce the initial anisotropy. The microplanes oriented in a yarn direction are associated with modified damage laws that reflect the tension-stiffening effect due to the multiple cracking of the matrix along the yarn.
The paper presents a meso-scopic modeling framework for the simulation of three-phase composite c... more The paper presents a meso-scopic modeling framework for the simulation of three-phase composite consisting of a brittle cementitious matrix and reinforcing AR-glass yarns impregnated with epoxy resin. The construction of the model is closely related to the experimental program covering both the meso-scale test (yarn tensile test and double sided pull-out test) and the macro-scale test in the form of tensile test on the textile reinforced concrete specimen. The predictions obtained using the model are validated using a-posteriori performed experiments.
Based on the German Code E DIN 19700 (2001) the Ruhrverband Essen in collaboration with RWTH Aach... more Based on the German Code E DIN 19700 (2001) the Ruhrverband Essen in collaboration with RWTH Aachen and Bauhaus University Weimar recently performed safety assessments of its barrages. In particular, the seismic slope stability of the rockfill dams and the hydro-fracturing problem of masonry dams have been analyzed in detail. Because of the importance of the structures and the potential damage involved in the collapse of a dam, the time-stepping algorithm was used in the seismic analysis of the slope stability instead of the simplified quasi- static Krey/Bishop method. In addition to the earthquakes specified by the German code, measured accelera- tion characteristics of the Roermond earthquake were applied. The safety assessment has been performed by postprocessing of the computed stress field histories to obtain the corresponding slope stability characteristics (Meskouris et al. 1999a, b). For the masonry dams the hydro-fracturing problem, which may be caused by the water penetrat...
This paper describes concepts used in the development of a technical information system (TIS) for... more This paper describes concepts used in the development of a technical information system (TIS) for supporting collaborative material research. The system has been set up to support the development of textile-reinforced concrete (TRC) by applying the modern theoretical concepts of software and database engineering to integrate the available open source tools in an effective way. The system works as a database powered internet server with a transparent definition of the product and process model.
In this paper the development of a consistent material model for textile reinforced concrete is p... more In this paper the development of a consistent material model for textile reinforced concrete is presented. Load carrying and failure mechanisms at the micro, meso and macro scales are described and models with the focus on the specified scales are introduced. The models currently being developed in the framework of the collaborative research center are classified and evaluated with respect to the failure mechanisms being captured. The micromechanical modeling of the yarn and bonding behavior is discussed in detail and the correspondence with the experiments focused on the selected failure and interaction mechanisms is shown. The example of modeling the bond layer demonstrates the application of the presented strategy.
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Papers by Rostislav Chudoba