Jan Bielak

Numerical and Experimental Characterization of Anchorage Length for Textile Reinforced Concrete

In this paper we propose an experimental and numerical framework for systematic characterization of anchorage behavior of textile fabrics used as reinforcement in Textile Reinforced Concrete (TRC). The experimental test setup utilized to examine the anchorage length and bond behavior can easily be adapted to the varying material characteristics of different textile fabrics. Depending on the fiber material and the type of impregnation resin, variable increments of anchorage length up to the full anchorage length necessary for roving rupture can be tested. The hydraulic clamping of the specimens allows for a rapid yet robust test procedure. Whereas steel reinforcement bars are usually tested in a single bar pullout test, the proposed method tests multiple rovings in parallel with a symmetric, double sided pullout from the concrete matrix. Thus, the test implicitly accounts for the statistical variation of bond characteristics of textile fabrics. The specimens are either cast directly or cut from actual prefabricated structural components such as thin facade panels. This allows for a realistic evaluation of the anchorage behavior of TRC components like plates and shells.

Towards Standardization: Testing and Design of Carbon Concrete Composites

The standardization of testing methods and design approaches is one key to overcome barriers which interfere radical innovation in the AEC (Architectural, Engineering and Construction) industry. Currently, the radical innovative Carbon Concrete Composite, including textile reinforced concrete (TRC), embraces a widespread set of testing methods. Depending on the fiber material, the textile binding type and its impregnation material properties, different methods are suitable to determine tensile strength, flexural strength and bond stress characteristics of the composite material. However, different test setups lead to scattering results and thus to a varying statistical distribution of the key input values for design. Furthermore, the testing methods must be consistent with the current design concepts for tension, bending and shear.

Extremely Light and Slender Precast Pedestrian-Bridge Made Out of Textile-Reinforced Concrete (TRC)

Textile-reinforced concrete (TRC) is an innovative composite material which uses mesh-like textile reinforcements and a fine-grained concrete as basic materials. Unlike steel, textiles are not susceptible to corrosion, thus it is possible to minimize the concrete cover to only a few millimeters. As a result, slender concrete constructions can be built, meeting the needs of modern architecture with both economical and environmental advantages.

Characterization Procedure for Bond, Anchorage and Strain-Hardening Behavior of Textile-Reinforced Cementitious Composites

A fast adoption of innovative composite materials such as textile reinforced concrete (TRC) in practice is hindered by the lack of efficient and standardized characterization and design procedures. In this paper, we discuss results of uniaxial tensile tests and double sided pullout tests. The analysis of the tests is done with a modelling framework for tensile behavior developed at IMB RWTH Aachen. The overall goal is to simulate the tensile response of composite specimen based on the reinforcement and matrix characteristics. Thus, the need for cost-intensive composite tensile tests could be reduced, which facilitates the material development and adoption of TRC in engineering practice.

A Modelling Framework for the Tensile Behavior of Multiple Cracking Composite

In this paper, we present a framework for modelling of the multiple cracking behaviors of unidirectional reinforced composites under tensile loading. The property of the bond interface between the matrix and the reinforcement has significant influence on the mechanical behavior. The proposed framework can handle a variety of bond properties, such as the random bond intensity of non-impregnated reinforcement consisting of multiple yarns, or the non-linear bond-slip law where the shear stress can be characterized as a non-linear function of the slip. We focus on the textile reinforced concrete (TRC) which uses impregnated textiles as reinforcement. Its bond property falls into the category of non-linear bond-slip law. A sequential inverse analysis procedure is proposed to derive the bond-slip law in TRC from the experimental results of pull-out tests. Based on the obtained bond-slip law, a local crack bridge model concerning the tensile behavior of a local crack bridge is formulated. Combining the crack bridge model with the crack detecting algorithm, the cracking history and the stress-strain curves can be numerically determined.