Applied Mechanics and Materials Vol. 827

Abstract: Glass has got important role in modern architecture not only because of its transparency, interior lighting and for aesthetical function but nowadays also more often for its load bearing function. Design of structural glass elements is limited by the lack of knowledge and standards, especially in case of stability problems of beams or columns. Slender glass beams with rectangular cross-section tend to fail because of instability.

Abstract: This paper presents results of study of behaviour of headed studs which are used for reinforcing of concrete structures. Numerical simulations of wall/slab joints reinforced by headed studs were carried out to find if there was some increase of wall/slab joint capacity due to the compressive zone in the joint. It was found that there is an increase of capacity of headed studs due to the compressive zone and the coefficient of capacity increase was introduced.

Abstract: Presented contribution deals with using textile reinforced concrete containing newly invented high strength cement matrix for strengthening concrete structures. The issue of old concrete ́s surface interaction with newly applied slim layer of textile reinforced concrete is investigated and verified by bending test. Water to binder ration under 0.3, maximum size of used silica sand 1.2 mm, and compressive strength over 100 MPa characterize used fine grain cement matrix. Over 12 months old beams with dimension 100 x 100 x 400 mm made from ordinary concrete were used for strengthening during performed experimental program. Strengthening took place on bending side. Different number (1, 3 and 5) of textile fabrics made from alkali-resistant glass (surface density 275 g/m²) was applied into slim layer of cement composite. Increasing number of used fabrics leads to different failure mode due shearing force action.

Abstract: This text is focused on GLULAM (glued laminated timber) beams and determination of their properties. This text is mainly focused just on part of more complex research of glued laminated timber beams. This text is focused on pulse method, which is used to determine the dynamic modulus of elasticity of GLULAM beams. This text will describe how the pulse method works, with basic description, describes the tested material and compare the results of testing. In the conclusion we discuss the results, make conclusions and describe the way of our further research of glued laminated timber beams.

Abstract: The paper deals with the effectiveness of CFRP confinement externally bonded on the surface of damaged stone masonry columns. The experimental measurement carried out within the DF12P01OVV037 research project [1] includes the mechanical behavior, specimen´s strength and failure modes. The results showed that the CFRP confinement may be considered as an effective stabilization technique able to increase the structural safety of damaged stone columns.

Abstract: The testing results obtained during investigation of 3D mat are presented in the article. The spatial mat is designed to provide a cheap, efficient and durable soil stabilization on slopes. The testing was focused on development of suitable methods to be used when assessing foil properties on-site. The tested samples were extracted from mats that were used for soil stabilization at the location of mine Nástup Tušimice (Company Severočeské doly, Czech Republic) and exposed to external environment and weathering for 2 years. The performance of the mats was compared with reference samples from unused mats stored for 2 years in laboratory conditions. The testing revealed that deterioration of the material is negligible over the period of 2 years.

Abstract: The present work is concerned with the evaluation of creep deformation developed during the four-point bending test of glued laminated timber beams. In particular, three deflections (at the mid-span of the beam, and below the points of load application) were recorded for each tested beam. The time variation of deflections at 110 loading levels was examined in details for the set of five beams. It can be seen that the effect of creep covers about 10 – 20% of the overall strain. To proceed with numerical simulations requires, however, building first a reliable computational model that agrees well with purely elastic response of the beam. Thus additional measurements were carried out assuming a rather short hold period to eliminate the creep effects. The results were then compared with numerical simulations promoting the computational model to be used in more advanced simulations incorporating a suitable rheological model.

Abstract: Unburned clay is a unique building material. It was used for the traditional engineering works for more some 9 thousands years. However, it was almost completely replaced in this role by modern building materials during second half of twentieth century. Because of that, its material characteristics, as its behaviour in the constructions, were never researched very rigorously. In last years, we could see increasing demand for use of this building material. Most of the contemporary unburned clay constructions are made of adobe bricks or pressed-down mud. Brick constructions are made of adobe brick and clay mortar. For both of them it is their mechanical properties, which determine their use in the construction industry. According to our experimental measuring, the tensile strength in bending of common adobe bricks is 2.5 MPa for pressing pressure of 6.6 MPa. The tensile strength in bending in clay mortar made of common clay is 0.45 MPa for pressing pressure of 1.55 MPa.

Abstract: The paper presents research in area of the measurement of cement paste creep. The propertiesof four month cement paste mixed with fly ash are presented. The creep and shrinkage are measuredinto the lever mechanism. The basic creep and creep of the saturated cement paste are calculatedfrom data of measurement. Finally, creep of four months old specimens is discussed.

Abstract: This investigation was focused on possibility of use recycled cement powder originating from the construction and demolition concrete waste as partial replacement of cement in concrete mixture. The main goal of this paper is the study of the mechanical properties development of the fine-aggregate concrete with partial cement replacement at the age 7, 14 and 28 days. The compressive strength and dynamic modulus of elasticity were tested in time. The recycled cement powder from fine recycled concrete, which was used as partial replacement of cement, had the same grain size as cement. The concrete mixtures contained 95 %, 90 % and 85 % of cement and residue has been replaced by recycled cement powder. Mechanical properties were tested on cubic and prismatic specimens.