This article focuses on researching the interactions of fiber concrete slabs with subsoil. The experimental series includes four slabs made of fiber concrete with different dosages of fibers, from 0 to 75 kg/m3. The slabs were exposed to a loading test on a specialized loading frame. The laboratory tests for detailed descriptions of the fiber concrete’s mechanical properties were also an integral part of the experiments, including tests of the compressive strength, the modulus of elasticity, and split and bending tensile strength. Each slab’s deformation in a particular load step was evaluated in two-dimensional (2D) sections based on data measured with displacement sensors and in three-dimensional (3D) charts with the use of interpolation.

AbstractThe article deals with the interaction of a reinforced concrete slab with subsoil. The paper contains a non-linear analysis based on an experiment of reinforced concrete slabs with dimensions 2000 x 2000 mm and thickness 150 mm. A steel mesh with a diameter of 8/100 mm was used as reinforcement. The calculations and analysis are complemented by a comparison with EC2 design approaches. The research area combines the design of concrete structure and geotechnical tasks. The real behavior of the concrete structure with subsoil is considered for the analysis for advanced design. The selected computational approach of nonlinear analysis allows to capture the change of stiffness after the creation of cracks and modelling the shear punch failure of the slab - the collapse of the structure. The paper focuses on comparing the experiment with the numerical model in select loaded states for various input parameters of subsoil. Based on the experiment and numerical analysis the failure mechanism was determined. It was the punching of the slab. The calculations and the experiment verified that the critically controlled perimeter is at a distance of 1d. The effect of the modulus of elasticity on the slab punch mechanism was verified. In case of low modulus of subsoil, the load-bearing capacity of the slab is significantly reduced. The punching mechanism is influenced not only by the mechanical properties of the concrete but also by the properties of the subsoil. The performed parametric study also verified the influence of the size the nominal cover reinforcement depending on the modulus of elasticity of the subsoil. The deformation variant finite element method and a 3D computational model were used for numerical modelling. Nonlinear analysis was based on the Newton-Rapson method.

A detailed analysis of concrete structures requires knowledge of the mechanical properties of the materials used. In the case of a non-linear analysis, the scope of the information needed is even greater. In particular, the tensile strength and fracture-mechanical parameters are required for the concrete. Prospective approaches that could increase the informative value of detailed analyses include the use of stochastic modelling. It particularly enables the definition of the effects of individual input parameters on the load capacity, failure mode, and general behaviour of the structure. The presented paper aims at a detailed analysis of a reinforced-concrete beam without shear reinforcement, which is based on a complex set of laboratory tests and non-linear analyses with a sensitivity study. The laboratory program includes different types of laboratory tests. Selected and missing material parameters of the concrete are calculated according to recommendations in scientific papers and the valid standards. The results are compared and discussed.

Abstract:The article handles potential approaches to design and determination of total load capacity of foundation slabs and floors. The research is focused on punching shear failure of reinforced ground supported slab. The article presents detailed results of the experiment made and advanced numerical modelling based on nonlinear analysis and application of fracture-plastic model. The experiment made included a 2.0 9 1.95 m reinforced concrete slab-on-ground of 120 mm thickness. The experiment was followed by a parametric study of total load capacity calculation with nonlinear analysis which is supplemented by calculations based on existing design model code.

The article deals with the field of use of acoustic emission (AE) measurement in engineering structures. The research particularly focuses on the assessment of acoustic emission during an experimental test of the load-carrying capacity of concrete slabs on the ground. A wider field of research includes structural and material optimization of advanced engineering structures. The tests of concrete slabs are then carried out in an alternate solution which differs in the used concrete or steel fibre reinforced concrete (FRC). The experimental program then includes typical measurement methods using displacement sensors and strain gauges. Non-destructive methods of measurement including acoustic emission have been used with an eye to the configuration of the experiment and deeper understanding of the actual behaviour and damage to the structure allowing for subsequent optimization and non-linear simulation of slab computation. The aim of the submitted article is to present and assess the acoustic emission as a non-destructive method which can be used to detect damage and determine the load-bearing capacity of the selected type of a FRC structure.