No abstract

Mechanical tests were performed at the Klokner Institute on samples of a textile glass reinforcement. These tests will be used for determining the modulus of elasticity of textile glass reinforcements and for assessing the maximal stress that the samples will withstand. Both of these quantities are required for further modeling of the structures and for designing elements made from textile reinforced concrete (TRC). The tests were carried out on a total of 10 samples made from a single piece of 2D net (produced by V. FRAAS, GmbH, Germany). The tests were carried out on AR-glass reinforcement (alkali - resistant glass) textile glass with 2400 TEX [g/km] fineness, which is often supplied with dimensions of 1 x 2 m. The first 5 samples were prepared in the direction of the warp (the direction of the load-bearing reinforcement), and the remaining 5 samples were prepared from the transverse direction (the direction of the weft). These samples were loaded by a constant force increasing up to collapse. Then the modulus of elasticity of the textile glass reinforcement and the stress at the strength limit were determined from the monitored data.

The paper is about a research focused on a development of thin slabs made from white UHPC. These slabs are reinforced by scattered PVA fibres and textile glass reinforcement in form of 2D net. The aim of the experiment is the development of tin slabs that can be used as facade or roof panels. The course of the experimental tests of these slabs and its correspondence with the numeric analysis made with ATHENA software is in the paper. Three slab specimens with size of 750 x 125 x 15 mm were tested in four-point bending. The white UHPC matrix was reinforced by the scattered PVA fibres and the 2D textile glass reinforcement with mesh 20 x 20 mm. The used 2D reinforcement was coated against alkali conditions, so called AR - Glass with 2400 TEX fineness. The reinforcement was placed and fixed near the lower surface of the slabs. The course of the tests was continually monitored by an automatic measuring unit where especially the acting force, the deformation in the middle of the span, the deformation in the supports and the progressive formation and development of cracks were detected. The numeric model was created in 3D surroundings of Gid 2011 program and then converted into ATENA software.

This paper focuses on the research carried out on thin plates made of white ultra-high performance concrete reinforced by PVA fibers and 2D textile glass reinforcement. These boards should be used for facades or roof panels. The paper presents a computer and experimental analysis of the loading of thin UHPC plates. For the purpose of the experiments, three specimens of a size of 750 x 125 x 15 mm were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.

Internet of Thing technology (IoT) is currently developed and IoT commercial networks are being operated and developed in the Czech Republic, as for example LoRa or SigFox. In order to monitor structures or environments (temperature or relative air humidity etc.) with use of these technologies, very cheap hardware can be used, as is the micro controller ESP32 (or its precursor ESP8266). More substantial part of costs represents programming and adjustment for the actual measurement. This article is containing pilot verification of the measuring system based on the above technology during the monitoring of relative displacements in cracks and temperatures of environment on the building structure of cultural monument Church of St. Martin in Zlatá Olešnice. We applied the measurement with sensors of displacement across cracks of the masonry structure in combination with the measurement of the air temperature. The measurement of some cracks proved that the relative displacement is significantly independent on the temperature and, therefore, the displacement is most likely influenced by the unstable conditions in the subsoil of the structure, which is also greatly affected by a ground moisture.