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The paper presents research focused on modeling of lightweight concrete beams combining reinforced and fiber concrete. The paper solves the selected case of the RC beam, which was experimentally tested. The advanced numerical model and calculation used for an experiment into account the non-linear behavior and collapse of the beam. For the experiment, a specific cross-section with an opening that relieves the beam is selected. Non-linear analysis in combination with the finite element method is used for numerical modeling. Specifically, 3D calculation model and fracture-plastic material for concrete are used.

The 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.

Concrete is typical composite material and its properties can be very variable. Material properties are also influenced with the technology of processing, manufacturing and treatment after concreting. Reinforcement in form of fibers is often added for improving tensile strength. This paper deals with specific testing of fibre concrete. Test results of series of specimens are presented for selected transport concrete composition, which is reinforced with amount of fibers 25, 50, 75 kg / m3. Fibers were added directly into the into the concrete mixer in the factory. Each series includes more than 25 test samples. The tests include the compressive strength of a cube and cylindrical, testing of modulus of elasticity, and the split tensile strength in the direction perpendicular to and parallel to the filling. Within the research project also a few types of bending tests were performed. Four variants of bending test that vary in span of 500 or 600 mm, samples with and without a notch, and in a three- / four-point configuration. As a summary, broader evaluation and functional dependencies are derived.

Advances in technology and sustainability requirements create substantial demand for material research. In construction industry, possibilities of innovation of concrete are opened by using recipes based on new activation methods, where alkaline activated composites can be included. This article focuses on this area where the results of the recipe verified under industrial conditions are presented, and the way of processing is significantly different from the laboratory conditions. The aim of the article is to present the material properties and differences of alkali activated specimens that are compared with series of common concrete material properties based on composition from the same aggregate material base. It was found that the most significant differences are the modulus of elasticity. In both of the recipes, the same design cube compressive strength is used. The article presented also experiment and nonlinear analysis of the alkali-activated beam without shear reinforcement, which was used to study the mechanism of damage and collapse of AAM beam. Nonlinear analysis was used thanks to complex knowledge of material properties. Numerical modelling uses the ATENA software. Test of small structural element is complemented by an advanced crack detection diagnosis with the use of acoustic emission.

This paper deals with analysis of set of reinforced concrete beams. Loading experiments of these beams were carried out and the results were documented and published earlier. Experiments involve several variants of spans, cross-sections and reinforcement so that various modes of failure of reinforced concrete structures are achieved. This paper compares the resistance of particular beams defined according to valid standard Eurocode 2 with non-linear analysis using advanced spatial 3D numerical models Cementitious material model based on fracture mechanics implemented in ATENA software. This paper outlines the wider evaluation of failure mode of beam and comparison of different calculations of resistance of the cross-section.

Sustainable development of concrete construction requires sustainable materials or sustainable binders. Specifically, alkali-activated materials (AAMs) are an interesting and wide group of materials. They have good strengths and are considered environmentally friendly materials because secondary materials are consumed during the preparation of AAMs. The durability of AAMs is also excellent. One of the most important parts of durability is frost resistance. The frost resistance of alkali-activated materials is usually very good. However, some studies showed opposite properties and poor frost resistance. The reason for this may be a different composition of the activator. The content of alkalis is often considered the main characteristic of alkali-activated materials. However, SiO2 content can play an important role too. This paper discusses the different results for the mechanical properties and frost resistance of different compositions of alkali activators made of sodium water glass with a silicate modulus modified with potassium hydroxide. The role of the activator content and the water-to-cement ratio in this phenomenon is discussed. The results of this article show that the strengths of AAMs are significantly affected by the curing method. Water curing reduced some of the strength of the specimens compared to foil-covered specimens. Frost resistance depends on the method of curing and on the composition of the activator, some concretes with high strengths showed very low frost resistance.

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&rsquo, 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&rsquo, 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.

Fiber-reinforced concrete has a wide application in practice, and many fields of research are devoted to it. In most cases, this is a specific problem, i.e., the determination of the mechanical properties or the test method. However, wider knowledge of the effect of fiber in concrete is unavailable or insufficient for selected test series that cannot be compared. This article deals with the processing of a comprehensive test study and the impact of two types of fibers on the quantitative and qualitative parameters of concrete. Testing was performed for fiber dosages of 0, 40, 75, and 110 kg/m3. The fibers were hooked and straight. The influence of the fibers on the mechanical properties in fiber-reinforced concrete was analyzed by functional dependence. The selected mechanical properties were compressive strength, splitting tensile strength, bending tensile strength, and fracture energy. The results also include the resulting load&ndash, displacement diagrams and summary recommendations for the structural use and design of fiber-reinforced concrete structures. The shear resistance of reinforced concrete beams with hooked fibers was also verified by tests.

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.

This article focuses on the analysis and numerical modeling of a concrete slab interacting with subsoil. This is a complex task for which a number of factors enter into the calculation, including the scope or dimension of the model, the non-linear solution approach, the choice of input parameters, and so forth. The aim of this article is to present one possible approach, which is based on a non-linear analysis and a three-dimensional computational model. Five slabs were chosen for modeling and analysis. The experiments involved slabs of 2000 &times, 2000 mm and a thickness of 150 mm, which were tested using specialized equipment. The slabs included a reinforced concrete slab, a standard concrete slab, and three fiber-reinforced concrete slabs. The fiber-reinforced slabs had fiber volume fractions of 0.32, 0.64, and 0.96%, which corresponded to fiber dosages of 25, 50, and 75 kg/m3. A reinforced concrete slab was chosen for the calibration model and the initial parametric study. The numerical modeling itself was based on a detailed evaluation of experiments, tests, and recommendations. The finite element method was used to solve the three-dimensional numerical model, where the fracture-plastic material of the model was used for concrete and fiber-reinforced concrete. In this paper, the performed numerical analyses are compared and evaluated, and recommendations are made for solving this problem.

The application of self-compacting concrete has found wide use in practice. However, its application is often limited by lack of knowledge on material parameters gained from laboratory tests, which results in difficulties in the design of progressive building structures and buildings where non-linear finite element analysis should be used. The submitted paper presents results of identification of mechanical and fracture properties of selected self-compacting concrete beams applicable for non-linear finite element analyses. A procedure dealing with the determination of mechanical and fracture properties from an extensive series of tests on notched beams is also presented. The studied material is a high-performance concrete reinforced with two types and three volume ratios of steel fibres. An inverse analysis in combination with a multi-criterial analysis is used for evaluation of fracture-mechanical characteristics.

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. Web of Science 63 2 620 608

The development of new structural systems, materials, and technologies enables the design and the implementation of progressive buildings meeting the demanding criteria of users and architects. However, using the new design approaches implies a need for knowledge about the behavior of the materials used, including their manner of disruption. This issue is also related to existing structures, where damage and accidents also occur. One of the solutions is the advanced acoustic emission diagnostics. This paper deals with the specific role of the interaction between the concrete slab and the subsoil. The paper aims to present the identification of crack formation, where acoustic emission measurements are compared to other measurement methods. The presented spatial graphs are used to evaluate the measurement and to compare the acoustic emission.

The article deals with approaches to the modeling of fiber-reinforced concrete with the finite element method and nonlinear analysis. The article aims to determine the input parameters and the mechanical properties for the selected modeling approaches. The chosen fiber-reinforced concrete has the dosage of 75 kg/m3 and two series, which differ, in the type of fiber. For determining the basic mechanical properties, destructive methods have been used. Their purpose has been to determine the compressive strength and the tensile strength. The three-point flexural tensile strength test has included the evaluation of load-displacement diagrams, which have been utilized during numerical modeling. Numerical modeling is based on a 3D computational model in the finite element method and on the fracture-plastic material model. The conclusion includes differences during modeling depending on the type of fiber used.

This article presents the results of static tests on bolted connections in squared and round timber with inserted steel plates. The experiment evaluates structural timber connections with different distances between the fastener and the loaded end at different moisture contents. Specimens were loaded by tension parallel to the grain and load-deformation diagrams were recorded. Fifty-six specimens with three different distances between the fastener and the loaded end, at different moisture contents, were tested. The results were statistically evaluated using regression analysis, complemented with load-deformation curves, and compared with calculations according to the valid standard for design of timber structures. A decrease in the evaluated load-carrying capacity with increasing moisture content was confirmed experimentally. A slight increase in the evaluated load-carrying capacity with increasing fastener distance from the loaded end was found. Web of Science 13 23 art. no. 5525

The joints in timber structures are often the decisive factor in determining the load-bearing capacity, rigidity, sustainability, and durability of timber structures. Compared with the fasteners used for steel and concrete structures, fasteners for timber structures generally have a lower load-bearing capacity and rigidity, with the exception of glued joints. Glued joints in timber structures constitute a diverse group of rigid joints which are distinguished by sudden failure when the joint&rsquo, s load-bearing capacity is reached. In this contribution, the load-bearing capacity of a longitudinal joint for a beam under simple flexural stress is analyzed using glued, double-sided splices. Joints with double-sided splices and connecting screws were also tested to compare the load-bearing capacity and rigidity. A third series of tests was carried out on joints made using glued double-sided splices augmented with screws. The aim of this combined joint was to ensure greater ductility after the load-bearing capacity of the glued splice joint had been reached.

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 X 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. Web of Science 12 1 art. no. 36

The goal of the paper is to model and evaluate the total load capacity of the reinforced concrete beams. A non-linear analysis and finite element method were used for that purpose. The model consists of 3D finite elements. The constitutive model of concrete for the non-linear analysis is based on a fracture-plastic theory. The input parameters are the data obtained in previous tests which included both standard tests and additional tests of the testing bodies. There is no shear reinforcement in the beams. The non-linear calculations were carried out for several variants. The study takes into considerations the influence of concrete properties as well as the size of the finite elements.

The paper compares the numerical models of and experiments with a beam. The purpose is to evaluate the nonlinear material model of a steel structure. The steel is modelled as an ideal elastic-plastic material. The FEM and eight-node isoparametric finite elements are considered in the analysis. The 3D calculations use different material constants and several approaches are being tested in order to create the computational models. The calculations are performed in the software application developed by our university.

The paper deals with the designing and analysing of concrete structures. A particular attention is paid to a multi-segment slab made from reinforced concrete. The purpose of the paper is to evaluate, in a non-linear analysis, impacts of input parameters of the concrete on the real load-carrying capacity of the ceiling which has been designed originally in DeMKP. FEM software applications have been used in the analysis. This is an in-house application DeMKP for designing the systems in line with standardised procedures. Another software is ATENA Science which can be used for non-linear analyses.

Concrete is frequently used when designing the civil engineering structures. It is, in particular, used for elements of the load-carrying systems. High strength concrete, fibres in concrete or recycled materials are employed as advanced solutions. It is necessary to identify the material properties of new materials and composites with respect to the future use. This is, particularly, the case of non-linear analyses which are performed in designs and analyses. This paper focuses on evaluation and modelling of three point flexural test of fibre concrete beams. The purpose is to evaluate the basic properties which will be used for constitutive models in the non-linear analyses. It is assumed that the constitutive models of concrete are based on the fracture-plastic theory. The modelling and analyses are performed in ATENA - the software application which is based on the Finite Element Method.

The paper deals with a numerical analysis of timber-concrete ceiling. The finite element method is used for the analysis. The calculation takes into account a dynamic effect of load. The structure creates the ceiling of the gymnasium. The goal of the paper is a study of ceiling eigenfrequencies and a maximum response to a harmonic excitation.

The purpose of this paper is to compare calculation of internal forces and deformations of slabs for two calculation methods: the finite element method and the finite difference method. Two concrete slabs have been analysed. In the case of the finite element method, different element mesh are used, providing, thus, solutions in different variants. The calculation and algorithms is based on a thin slab theory. Variants calculate in program Scia Engineer effects of shearing forces by means of the Midlins theory or thin slab theory. Algorithms for the calculation were developed in Matlab.

The paper deals with mechanical properties of high-strength concrete, which are illustrated in various laboratory tests. The aim of the paper is to compare the possibilities of concrete compressive and tensile strength assessment and modulus of elasticity assessment. Results of nine type laboratory tests are presented in summary. Tested material properties are complemented with testing of small structural element, the beam without shear reinforcement. The behaviour of structural element is analysed also with a non-linear numerical model that respects the quasi-brittle properties of the concrete, where fracture-plastic model for concrete is used.

The paper deals with the possibility of using the acoustic emission (AE) measurement for the identification of cracks and failure in fibre concrete slabs in interaction with subsoil. In this specific task it is not possible to check visually cracking on the slab bottom surface. The research task included an experimental load test of a slab and supplemented laboratory testing to determine the mechanical properties of fibre concrete. The concrete used has a dosage of 25 kg/m3 fibres. Laboratory tests included cube and cylindrical compressive strength, flexural strength and split tensile strength. Homogeneity of the concrete mixture, i.e. uniform distribution of the fibres, was proven with testing of the split tensile strength both evenly and perpendicularly to the direction of filling the concrete mixture into the form. Experimental load test of slab on subsoil was performed on fibre concrete slab with plan dimensions 2000 x 2000 mm and thickness 150 mm. Concrete slab was loaded in the middle with force load step 75 kN. AE measurements were provided using track sensors.

The civil engineering belongs to one of the most important industrial area and to a sphere of increased requirements for Health & Safety. With the civil activities, there is connected the wide research in a lot of spheres such as material research, advanced analysis of building structures, experiment research and the others. The presented paper deals with possible approaches to safety management system resulting from the most widespread system used in praxis. This article also discusses modern elements of safety management.

This paper deals with a modeling of the composite timber-concrete ceiling structure. In the analysis of the composite structure, there is the slip using the contact elements and volume finite elements considered. Numerical modeling is complemented by an analytical calculation. This article aims to determine the stiffness of a particular type of glued strip. Totally eight models of the composite timber-concrete structure have been studied.

This paper describes the use of models of fracture-plastic materials for reinforced concrete in numerical modelling of beams made from reinforced concrete. The purpose of the paper is to use of a model of concrete for modelling of a behaviour of reinforced concrete beams which have been tested at the University of Toronto within re-examination of classic concrete beam tests. The original tests were performed by Bresler- Scordelis. A stochastic modelling based on LHS (Latin Hypercube Sampling) has been performed for the reinforced concrete beam. An objective of the modelling is to evaluate the total bearing capacity of the reinforced concrete beams depending on distribution of input data. The beams from the studied set have longitudinal reinforcement only. The beams do not have any shear reinforcement. The software used for the fracture-plastic model of the reinforced concrete is the ATENA.