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
Textilbeton ist ideal, um Leichtbau mit Beton zu betreiben, da bereits mit sehr dünnen Schichten eine hohe Tragfähigkeit erreicht werden kann. Aufgrund der Leichtigkeit und der Flexibilität seiner Bewehrung ist Textilbeton vor allem prädestiniert dafür, freie Formen zu realisieren. In Verbindung mit innovativen Herstellungsmethoden besteht zudem die Möglichkeit, eine neue Formensprache im Betonbau zu etablieren. Dass dieses Potenzial nicht nur Ingenieure und Architekten interessant ist, sondern auch für Künstler und Designer, wird im zweiten Teil des Beitrags gezeigt. Free forms with TRC Textile reinforced concrete is ideal to build lightweight concrete structures, because a high load capacity can already be reached with very thin layers. The textile reinforcement is lightweight and flexible. Therefore, TRC is especially predestined to realize free forms. In combination with innovative production methods, we also have the option to develop a new distinctive design idiom in concrete construction. In the paper we also show, that this enormous potential is not only interesting for engineers and architects, but also for artists and designers.
The Carola Bridge (Carolabrücke), built in 1971, has a length of approximately 375 m and takes the tram and the B 170 federal road in Dresden across the river Elbe. The intensive use of the bridge and deficits in user‐friendliness made building measures inevitable. One part was the widening of the upstream bridge cap. Here, the application of a new nonmetallic reinforcement within the concrete cover was planned to improve the service life of the cap, a so far unique method. Based on an installation test and an investigation of the cracking behavior, both described in the paper, two reinforcement configurations were selected for practical application. The project provides an ideal opportunity to bring carbon and basalt reinforcements closer to the public and to demonstrate their cast in during normal operation on a concrete construction site.
Carbonbeton rückt immer mehr in den Fokus von Planern, Architekten oder Bauherren. Dies begründet sich in den Vorteilen des Baustoffs, wie der enormen Beton-und Ressourcenersparnis oder der Möglichkeit, wesentlich filigranere Strukturen umzusetzen, die sich durch den Ersatz der Stahlbewehrung durch hochleistungsfähige Carbonfasern ergeben [1-5]. Problematisch ist jedoch, dass konventionelle Verbindungselemente für den Stahlbetonbau nur bedingt für Bauteildicken zwischen 20 und 70 mm, wie sie im Carbonbetonbau üblich sind, konzipiert sind. Carbonbeton eignet sich zur Umsetzung einer modularen Bauweise. Dabei werden vorgefertigte Module zur Baustelle transportiert und dort miteinander verbunden [6]. Der Transport sowie die einfache und sichere Montage und Demontage führen zu bisher unbeachteten Anforderungen an die Verbindungstechnik. Um die Vorteile und das Potenzial des Carbonbetons zur Umsetzung einer modularen Bauweise voll ausnutzen zu können, sind neue Verbindungstechniken nötig.
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