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Structural optimization within concrete construction has been increasingly taken up in research within the last two decades. Possible drivers are the need for material-reduced and thus resource-efficient structures as well as recent advancements in automated concrete construction. However, structural concrete is characterized by nonlinear material behavior. Consequently, the merge of structural concrete design and topology optimization is not trivial. This paper reviews and assesses the topic of topology optimization within concrete construction, carrying out an extensive quantitative as well as qualitative review on practical and numerical applications. The following research areas are identified: Multimaterial modeling, stress constraints, concrete damage modeling, strut and tie modeling, combined truss-continuum topology optimization, the consideration of multiple load cases, a focus on construction techniques and alternative approaches. Although the number of research papers dealing with the topic of topology optimization in concrete construction is numerous, there are only few that actually realized topology optimized concrete structures. In addition, only a little number of experiments was performed for an objective evaluation of the found geometries so far. Concluding this review, a list of future challenges, like the incorporation of sustainability measurements within the optimization process, is given and thus serves as a guidance for subsequent research.

Der Einsatz und die Verfügbarkeit von Bewehrung aus Carbonfaserverbundkunststoff (CFK) steigen stetig, weshalb ein umfangreiches Verständnis der Verbundeigenschaften essenziell ist. Die vorliegende Publikation gibt einen Überblick über unterschiedliche Ausführungsformen von CFK‐Stäben sowie über den Einfluss von ausgewählten Parametern auf das Verbundverhalten. Der Fokus wurde auf Stäbe mit straffer Umwickelung aus CFK‐Fasersträngen gelegt und die Konkurrenzfähigkeit im Vergleich zu anderen, beispielsweise subtraktiv bearbeiteten, eingefrästen Stäben wird aufgezeigt. In 84 Ausziehversuchen wurde das Verbundverhalten von umwickelten CFK‐Stäben in vier Betonarten getestet. Bei den untersuchten Stäben wurden dabei die Wendelbreite und ‐dicke, die Wendelsteigung, der Wendelabstand und der Stabdurchmesser variiert. Die Versuchsergebnisse werden in Verbundspannungs‐Schlupfdiagrammen präsentiert, verglichen und abschließend diskutiert.

The concrete industry accounts for a significant amount of CO2 emissions worldwide. One approach to counter this issue includes material reduction of structural components via the use of non-metallic reinforcement, such as carbon, glass and basalt fibre reinforced polymers. On the one hand, non-metallic reinforcement. However, as its environmental impact has not been sufficiently investigated yet, a Life Cycle Assessment of the production phase is presented within this paper. In a first step, the environmental impact of the sole various reinforcement components and types is compared to each other per mass, per tensile or rather yield strength as well as density unit, at which an environmental disadvantage of especially carbon-fibre reinforced polymers is apparent in most cases. In a further step, a focus is put on applying the environmental data of carbon-fibre reinforced polymers to a pedestrian bridge, which is finally compared to a conventionally reinforced concrete bridge and a steel bridge with similar boundary conditions. The latter results indicate that an adequate application of carbon-fibre reinforcement in structural components has the potential to lead to designs of less environmental impact in comparison to conventionally reinforced pendants.

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