At the Institute of Concrete Structures, Technische Universität Dresden, a new precast ceiling system comprised of an arch and a beam at each longitudinal edge was investigated. The innovative composite material carbon reinforced concrete allows thereby a fresh way of thinking for civil engineering with lightweight constructions but still high bearing capacity. This variation of a beam has only straight rebars as main reinforcement. Four prototypes with a length of 4.50 m were produced and tested at Otto–Mohr‐Laboratory of TU Dresden. Except of the supports, the structure has a thickness between 40 and 45 mm, so a reduction of the dead load up to 70.0% compared to a usual rectangular cross section made of common steel reinforcement and the same concrete could be achieved. The experimental ultimate loads of the first three tested elements were thereby higher than the calculated ultimate load of the common reinforced concrete structure.
The load-bearing behavior and the performance of composites depends largely on the bond between the individual components. In reinforced concrete construction, the bond mechanisms are very well researched. In the case of carbon and textile reinforced concrete, however, there is still a need for research, especially since there is a greater number of influencing parameters. Depending on the type of fiber, yarn processing, impregnation, geometry, or concrete, the proportion of adhesive, frictional, and shear bond in the total bond resistance varies. In defined profiling of yarns, we see the possibility to increase the share of the shear bond (form fit) compared to yarns with a relatively smooth surface and, through this, to reliably control the bond resistance. In order to investigate the influence of profiling on the bond and tensile behavior, yarns with various profile characteristics as well as different impregnation and consolidation parameters are studied. A newly developed profiling technique is used for creating a defined tetrahedral profile. In the article, we present this approach and the first results from tensile and bond tests as well as micrographic analysis with profiled yarns. The study shows that bond properties of profiled yarns are superior to conventional yarns without profile, and a defined bond modification through variation of the profile geometry as well as the impregnation and consolidation parameters is possible.
Parking garage buildings are usually comprised of steel reinforced concrete (RC) slabs. Unfortunately, there are often cases of damage caused by the high exposure to corrosive chemicals. To prevent corrosion of the reinforcement, especially the ceilings must be coated with expensive protection systems. Due to the not-corrosive nature of carbon fibers, carbon RC is a perfect solution for those structures. But before using carbon RC for parking slabs, the problem of the end anchorage of the reinforcement by short-end anchorage lengths had to be solved. Therefore, a new anchorage method for carbon RC is described in detail in this publication. A large-scale test had been conducted to show the potential of carbon RC for parking slabs and to prove the ability of the developed new-end anchorage method. Also, an analytical recalculation of the large-scale test is presented.
Segment bridge of textile reinforced concrete -Rottachsteg Kempten in the AllgäuOn account of its very good mechanical properties textile reinforced concrete (TRC) is a material to be best to do lightweight concrete constructions. With this material it is possible to realize prefabricated concrete bridges with a size that was not possible yet due to limits in transport. Shorter construction or traffic blockages times are also a positive effect and with this economic and qualitative advantages are achievable due to prefabrication. A praxis test was done with a bridge prefabricated in Oschatz/ Saxony and transported to Kempten/Allgäu for mounting. The Rottach-Bridge does prove and demonstrate that textile reinforced concrete constructions can also assert themselves economically in the market. The bridge was put into operation in autumn 2007 and now has proved itself already in sixth winter. This is taken as an occasion to report in this paper on the design, calculation and preparation of textile concrete bridge Kempten. This report is based on [1] and takes over parts from this. Bild 1 Schematischer Aufbau von textilbewehrtem BetonSchematic structure of TRC
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