CRC 528-B1: Experimental determination of the stress-strain behaviour of TRC
Table of contents
Project data
| Titel | Title SFB 528-B1: Experimentelle Ermittlung des Spannungs-Dehnungs-Verhaltens von Textilbeton | CRC 528-B1: Experimental determination of the stress-strain behaviour of TRC Förderer | Funding Deutsche Forschungsgemeinschaft (DFG) / SFB 528 Zeitraum | Period 07.2008 - 06.2011 Leiter | Project managers Prof. Dr.-Ing. Manfred Curbach, Dr.-Ing. Frank Jesse Bearbeiter | Contributor Dr.-Ing. Frank Jesse, Dipl.-Ing. Dirk Jesse, Dipl.-Ing. Katrin Schwiteilo |
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Report in the yearbook 2009
TRC Under Biaxial Tension
Test-Setup for biaxial tension-tension-tests
Textile reinforced concrete (TRC) is a new composite material containing reinforcement comprised of a variety of technical textiles (i.e., yarns consisting of thousands of filaments). There is a strong dependency of the composite load-bearing behavior both from the bond between filaments and the bond between filaments and the matrix. Lateral tensile loading may lead to a decrease in strength. It is known from biaxial tensile tests of RC components that cracks located parallel to reinforcement reduce bond stresses between concrete and steel and, thus, reduces the tension stiffening effect. The high sensitivity of load-bearing behavior of TRC contrasted to the bond characteristics present leads to the expectation that cracks induced by tensile load in lateral direction will have a consideral impact on the load-carrying behavior in the longitudinal direction.
Experimental Research
This question has been experimentally examined by conducting biaxial tensile load tests on planar specimens. The technologically induced differences of the warp and weft threads of the fabric reinforcement lead to specific load-bearing behavior, making TRC an asymmetric, anisotropic material. This asymmetry requires the study of the entire tension-tension-quadrant to completely describe the material behavior in the warp and weft direction, as well as existing interconnections.
Test Results
As expected, there is no effect on uncracked TRC. The stress level at initial cracking – the transition from the uncracked to cracked state – decreases proportionally to the applied stress ratio, σ1/σ2; however, counter to this, there is no noticeable impact on the stress level that can be directly attributed to the lateral tension present.
There are obvious effects on the behavior after cracking has been completed. This occurs when the crack pattern, being parallel to the reinforcement, has developed extensively throughout the specimen as a result of lateral tensile loads. Stiffness declines significantly at this point as a consequence.
Information gain concerning the ultimate load capacity was limited as load relief cuts in the geometry of the specimens generated local stress peaks and introduced the predominant failure-mode, thus superposing any specific material effects. Test results, therefore, indicate no noticeable effect on the ultimate load capacity. A portion of current research is devoted to a closer examination of the ultimate limit state.