Sandra Gelbrich

Fiber-Reinforced Polymers Based Rebar and Stirrup Reinforcing Concrete Structures

Fiber-plastic composites offer an interesting alternative to concrete reinforcement. In order to expand the application spectrum of reinforcing elements in fiber composite construction, a new steel-free bracing system with reduced radii of curvature has been developed. An improvement in load carrying capacity could be proven in extensive investigations based on international testing methods and verified by practical tests. With the help of newly reinforced precast concrete elements from the area of waterways and traffic routes, a high potential for lightweight construction and resource efficiency can be impressively demonstrated.

Flexible fiber-reinforced plastic formworks for the production of curved textile-reinforced concrete

A new constructive and technological approach was developed for the efficient production of large-dimensioned, curved freeform formworks, which allows the manufacturing of single- and double-curved textile-reinforced concrete elements. The approach is based on a flexible, multi-layered formwork system, which consists of glass fiber–reinforced plastic. Using the unusual structural behavior caused by anisotropy, these glass fiber–reinforced plastic formwork elements permit a specific adjustment of defined curvature. The system design of the developed glass fiber–reinforced plastic formwork and the concrete-lightweight-elements with stabilized spacer fabric was examined exhaustively. Prototypical curved freeform surfaces with different curvature radii were designed, numerically computed, and produced. Furthermore, the fabric’s contour accuracy of the fabric was verified, and its integration was adjusted to loads. The developed textile-reinforced concrete had a high three-point bending tensile strength. Beyond that it was ensured that the textile-reinforced concrete had a high durability, which has been shown by the capillary suction of deicing solution and freeze–thaw test with a low amount of scaled material and a relative dynamic E-modulus of 100% after 28 freeze–thaw cycles.

Integration of Mineral Fiber Semi-Finished Products in Bituminous Matrices

This thesis investigates the development of an innovative fibre reinforced composite. A developed textile, consisting of mineral fibres that is embedded in a special mastic asphalt matrix. The integration of a grid shaped textile structure into the asphalt cause an inner reinforcement of the asphalt layer. This leads to a significant enhancement towards the tensile strength during bending. It also gives resistance to deformation. Rut formation is minimized and the thickness of the asphalt layer can be reduced.

Support Structures in Lightweight Design for the Construction of Resource Efficient Bridges

Modern civil engineering is characterized by resource and energy efficiency, and functional integration. The focus of modern architecture is therefore increasingly on free-formed buildings with organic shapes and biomorphic structures. The basis of new buildings still consists of conventional materials like steel, glass and reinforced concrete. However, the applicability of these materials is limited, regarding lightweight design, freedom of design, efficiency and functional integration. Innovative projects either cannot be implemented, or would be put to enormous costs and expenditure of resources.The theoretical and experimental basis for this functionally integrated support structure was established within the scope of the research project “New lightweight structural components and processing technologies for the application in support structures”, supported by the Sächsische Aufbaubank SAB.The main objective was to develop material and design for a lightweight modular support structure and to implement it by means of innovative production methods. New approaches included the application of glass-fiber-reinforced plastic (GFRP) due to its favorable mechanical properties, low susceptibility to corrosion and load-adjusted dimensioning.In connection with the realization of the production, different technological concepts were analyzed with reference to their suitability, integration of required force transmission and further functions during and after production. The lightweight elements were analyzed on a laboratory scale with regard to their production and their mechanical properties. A holistic production and tool concept resulted from these tests, that pictures the complete process chain from textile to component. The results were implemented in practice in form of an interactive honeycomb-bridge which was built in Chemnitz.

Textile Reinforced Lightweight Shells

Modern architecture is dominated by the tendency to design organically shaped filigree buildings. The resource and energy efficient construction of multifunctional buildings is as important as a broad variety of possible shapes. Multi-material support structures and shell constructions in lightweight design that also take over e. g. lighting and monitoring are needed for these purposes. Textile reinforced lightweight shell structures have been developed at Technische Universität Chemnitz within the scope of research projects. They consist of a hybrid material from carbon-fiber-reinforced concrete and glass-fiber-reinforced plastic. Thanks to the coupling of the positive material characteristics, the combination of two different composite materials results in a hybrid material with a total thickness of 15 mm, which has a high fatigue strength (XF4) and surface quality (exposed concrete). Furthermore, the hybrid is characterized by excellent compressive strength (120 MPa) and bending tensile strength (150 MPa), low susceptibility to corrosion and free formability. Therefore, it is highly suitable for thin-walled filigree lightweight shell structures. A research pavilion with a size of 4 x 4 x 3 m3 (l x w x h), made from textile reinforced lightweight shells, was built on the campus of TU Chemnitz, to test the theoretical investigations. Specially developed tensile sensors for the active lighting and determination of the elongations were integrated into the different layers. This aimed at an online-monitoring of the shell support structure.