Applied Mechanics and Materials Vol. 617

Abstract: The paper deals with use of the meshless method for incompressible fluid flow analysis. There are many formulations of the meshless methods. The article presents the Meshless Local Petrov-Galerkin method (MLPG) – local weak formulation of the Navier-Stokes equations. The shape function construction is the crucial part of the meshless numerical analysis in the construction of shape functions. The article presents the radial point interpolation method (RPIM) for the shape functions construction.

Abstract: The paper deals with use of the meshless method for soil subsurface settlement analysis. There are many formulations of the meshless methods. The article presents the Meshless Local Petrov-Galerkin method (MLPG) – local weak formulation of the equilibrium equations. The main difference between meshless methods and the conventional finite element method (FEM) is that meshless shape functions are constructed using randomly scattered set of points without any relation between points. The Heaviside step function is test function used in the meshless implementation presented in the article. Heaviside test function makes weak formulation integral very simple, because only body integral in governing equation is due a body force.

Abstract: The experimental studies of flat and relief glass-plastic reinforcement bond with concrete were conducted. The comparative analysis of obtained experimental data with results of other researchers in field of reinforcement and concrete bond was made. It was identified that composite reinforcement with flat winding has better bond characteristics in comparison with steel reinforcement and other winding types composite reinforcement. The analytical dependencies, allowing to simulate the process of fiber-plastic reinforcement bond with concrete, were obtained. The finite element modeling of deformation process of concrete foundation of transport constructions with fiber-plastic reinforcement were made.

Abstract: Fatigue and fatigue damage leads to a change in material properties that can lead to the element failures. Generally, it is necessary to verify the influence of the fatigue effects on the concrete members according to European standard EC2, [1]. FRP materials have been possibly used for the fatigue damage structure rehabilitation. There we can apply the condition of the limit boundaries stress on concrete and limit force in FRP material theoretical approach. Fatigue assessment will be analyzed for T-beam cross section with reinforcement and strengthened FPR material in this paper.

Abstract: Ultra High Performance Concrete - UHPC has become increasingly used. Its outstanding features are generally known. It is a fact that the bond of the reinfocement in UHPC is better than that in ordinary concrete, but this bond needs to be quantified .The aim of the experimental research was to determine the average bond stress between prestressing strands and different types of UHPC and to show very significant increase in the average shear stress in bond with UHPC compared to ordinary concrete. In order to determine the bond capacity, an experimental research was carried out. Experimental details of the models in real structures – parts of prestressed girders made from UHPC, were tested in the laboratory and the results were compared with specimens prepared according to standard. The influence of different material properties and different anchorage length of prestressing strands to bond behavior of UHPC was examined in pull out tests. Test results of bond test led to the conclusion that the application of UHPC can significantly reduce the anchorage length of reinforcement compared with the ordinary concrete.

Abstract: This paper is focused on cement specimen testing by impact excitation non-destructive technique. The impulse excitation method was used for measuring of the natural frequencies and modes of longitudinal, transversal and torsional vibration of the specimens. The objective was to find dynamic properties of the specimens without a crack, with a crack and with a healed crack by cement paste and based on their comparison detect and localize the crack.

Abstract: The paper describes experiments carried out in laboratories KU CVTU in Prague and subsequent demonstration of the application of their results in practice in two practical examples reinforcement structures, reinforced concrete frame and reinforced concrete girder bridge.

Abstract: Mechanical fracture parameters obtained from three-point bending tests on concrete specimens with a central edge notch are introduced in this paper. A total of four sets of specimens were tested. The concrete used in each set differed in cement dosage, which ranged from 250 to 455 kg per m³ of fresh concrete. Three specimens in each set were tested at the age of 28 days. Increasing the dosage of cement influences the mechanical fracture properties of concretes in both positive and negative ways.

Abstract: New nanomaterials such as carbon nanotubes and nanofibres considerably improve performance of current building materials and they can contribute to new application facilities. Alkali activated slag is a material having a great potential to be used in practice. The main drawback of this material is a high level of autogenous and especially drying shrinkage, which causes a deterioration of the mechanical fracture properties. The aim of this paper is introduce the effect of carbon nanotubes admixture on the microstucture and mechanical performance of alkali activated slag mortars. The three-point bending tests of specimens with central edge notch were performed. Method of acoustic emission was used during this testing.

Abstract: The paper deals with identifying of the damage model for a bundle of T300 and AS4D fibers under tensile load. The damage model is implemented in ANSYS for a one-dimensional bar element and obtained the strain-stress response of a bundle of fibers. The delamination of laminate plate, which consists of unidirectional fiber reinforced layers, is investigated. The methodology adopts the first-order shear laminate plate theory and fracture and contact mechanics. Within the interface modeling there are calculated the individual components of energy release rate along the lamination front. Numerical results are given for mixed mode delamination problems. Numerical example is done by the commercial ANSYS code.