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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Theoretische und experimentelle Untersuchung des spaltungsinduzierten Versagens von TRC Prüfkörpern

Schoene, Jens, Reisgen, Uwe, Schleser, Markus, Jeřábek, Jakub 01 December 2011 (has links) (PDF)
Bewehrungen mit einer hochmoduligen Polymertränkung erreichen im Betonbauteil Textilspannungen von über 1200 N/mm². Ab diesem Niveau wurden in Dehnkörperversuchen Längsrisse und Betonabplatzungen beobachtet. Für die Eingrenzung und Identifikation der elementaren, verantwortlichen Mechanismen weisen großformatige Dehnkörper störende Einflüsse von Randeffekten und Imperfektionen auf. Daher wurde ein neuer Versuchsaufbau entwickelt, bestehend aus einem in einen Betonquader eingebetteten Einzelroving. Die simple Herstellung und die Verlässlichkeit dieser Kategorie von Experimenten in Bezug auf die Reproduzierbarkeit und der geringen Streuung der Resultate machen sie zu einer robusten Grundlage für experimentelle Untersuchungen des Verhaltens von TRC. Die experimentell ermittelten Bruchlasten werden zunächst bezüglich ihrer Leistung diskutiert und dann die beobachteten Bruchvorgänge kategorisiert hinsichtlich kompatibler mechanischer Hypothesen für die Initiierung von Längsrissen und des Spaltversagen. / Reinforcements with a high-modulus, polymeric impregnation achieve textile tensions of 1200 N/mm² and more in concrete parts. Starting at this level longitudinal cracks and splitting were observed in tests. In order to isolate and identify the fundamental, responsible mechanisms large-scale specimen show an interfering impact of boundary effects and imperfections. Therefore a new test set-up was developed, consisting of a single roving embedded in a single concrete cuboid. The simplicity of production and reliability of this class of experiments in terms of repeatability and low scatter of results makes them a robust basis for experimental investigation of TRC behavior. The experimentally obtained strengths are discussed in terms of the performance, followed by the categorization of observed failure patterns with respect to the available mechanical hypotheses of the longitudinal crack initiation and splitting failure.
2

Theoretische und experimentelle Untersuchung des spaltungsinduzierten Versagens von TRC Prüfkörpern

Schoene, Jens, Reisgen, Uwe, Schleser, Markus, Jeřábek, Jakub January 2011 (has links)
Bewehrungen mit einer hochmoduligen Polymertränkung erreichen im Betonbauteil Textilspannungen von über 1200 N/mm². Ab diesem Niveau wurden in Dehnkörperversuchen Längsrisse und Betonabplatzungen beobachtet. Für die Eingrenzung und Identifikation der elementaren, verantwortlichen Mechanismen weisen großformatige Dehnkörper störende Einflüsse von Randeffekten und Imperfektionen auf. Daher wurde ein neuer Versuchsaufbau entwickelt, bestehend aus einem in einen Betonquader eingebetteten Einzelroving. Die simple Herstellung und die Verlässlichkeit dieser Kategorie von Experimenten in Bezug auf die Reproduzierbarkeit und der geringen Streuung der Resultate machen sie zu einer robusten Grundlage für experimentelle Untersuchungen des Verhaltens von TRC. Die experimentell ermittelten Bruchlasten werden zunächst bezüglich ihrer Leistung diskutiert und dann die beobachteten Bruchvorgänge kategorisiert hinsichtlich kompatibler mechanischer Hypothesen für die Initiierung von Längsrissen und des Spaltversagen. / Reinforcements with a high-modulus, polymeric impregnation achieve textile tensions of 1200 N/mm² and more in concrete parts. Starting at this level longitudinal cracks and splitting were observed in tests. In order to isolate and identify the fundamental, responsible mechanisms large-scale specimen show an interfering impact of boundary effects and imperfections. Therefore a new test set-up was developed, consisting of a single roving embedded in a single concrete cuboid. The simplicity of production and reliability of this class of experiments in terms of repeatability and low scatter of results makes them a robust basis for experimental investigation of TRC behavior. The experimentally obtained strengths are discussed in terms of the performance, followed by the categorization of observed failure patterns with respect to the available mechanical hypotheses of the longitudinal crack initiation and splitting failure.
3

Experimental and Numerical Analysis of Spalling Effect in TRC Specimens

Jerabek, Jakub, Keil, Allessandra, Schoene, Jens, Chudoba, Rostislav, Hegger, Josef, Raupach, Michael 03 June 2009 (has links) (PDF)
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 matrix follows a non-linear bond-law calibrated using pull-out tests. The epoxy-impregnated reinforcement is considered as a homogeneous bar.
4

Experimental and Numerical Analysis of Spalling Effect in TRC Specimens

Jerabek, Jakub, Keil, Allessandra, Schoene, Jens, Chudoba, Rostislav, Hegger, Josef, Raupach, Michael 03 June 2009 (has links)
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 matrix follows a non-linear bond-law calibrated using pull-out tests. The epoxy-impregnated reinforcement is considered as a homogeneous bar.
5

Effectiveness of Waterproofing Membranes for Precast Prestressed Concrete Adjacent Box-Beam Bridges

Almonbhi, Ali O. 23 May 2018 (has links)
No description available.

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