Jana Vaskova

Fibre Concrete Foundation Slab Experiment and FEM Analysis

In November 2013 an experiment was carried out using the testing equipment called stand. During the experiment was loaded steel-fiber reinforced concrete foundation slab model. The stand measures deformation and monitors interaction between stress and deformation. The purpose of this paper is comparison of values measured during the experiment and results of numerical calculations based on FEM. The stress strain analysis of elastic halfspace by means of Gauss numerical integration and Jacobean of transformation is presented here. The objective of this paper is also improving and developing the soil-structure interaction analysis based on the experimental results and FEM.

Numerical Modeling of the Subsoil-Structure Interaction

Numerical interaction model of reinforced concrete slab and subsoil was created in ANSYS. Input data for numerical analysis were obtained during experimental loading test of reinforced concrete slab. Loading test was performed using unique experimental equipment constructed in the area of Faculty of Civil Engineering, VŠB-TU Ostrava. Analysis of interaction of reinforced concrete slab with subsoil was solved with application of inhomogeneous half-space. Application of inhomogeneous half-space allows better capture the subsoil behaviour and its increasing modulus of deformability with increasing depth of subsoil model. Homogeneous half-space this takes no account. Reinforced concrete slab was cracked during an experiment. The effect of cracks was also taken into account in the numerical model of reinforced concrete slab using derived modulus of elasticity of cracked concrete. Values calculated by all types of interaction models were compared with values measured during the loading test of reinforced concrete slab.

Experimental Testing of Shear Resistance on SFRC Slab Structures

This paper deals with foundation slabs on the subsoil which are not reinforced with classically reinforcement but they are reinforced with steel fibers. It will be described several experimental test of FRC foundation slab which were reinforced with different amount of fibers. All tested slabs had dimension by 2.0 x 2.0 m and thickness 0.15m. On those slab a lot of physical quantities were measured and this paper focus especially on shear resistance.

Developing of Hydration Heat of the Massive Foundation in the Třinecké Železárny

Heavy industry, industrial plants and technology facilities use really big manufacturing units or assemblies with the weight of tens of tons. In case of rotary kilns, the weight can reach hundreds of tons. During the production process, those units move, creating, in addition to considerable static effects, big dynamic effects. Industrial facilities often face failures of the reinforced concrete foundation which is loaded dynamically by a rotating machine. Such failures typically result in cracks and failures of any of the foundation cross-section. Thus, a part of the foundation starts deviating, the rigidity goes down, geometry of the machine position is changing and an accident may occur - for instance, bearings may fail or malfunctions may occur in the machine. This has also happened in the case described in this article. The subject of the article is the large foundation structure of the rolling device in the Block Mill I in Třinecké železárny a.s. The slab of the foundation structure is approximately a T-shape, which has nearly 43 m in one direction and over 30 m in the other direction. The monolith foundation slab will be 2.0 m thick, the whole foundation structure will be 2.0 - 8.0 m thick. With such an extensive foundation, considerable attention must be paid not only to the design and realization, but also to the effect of the hydration heat.

3D Numerical Model of the Subsoil-Structure Interaction and Comparison of the Results with Experimentally Measured Values

The influence of the physically-nonlinear behaviour of the structure and interaction between the upper structure and foundation are the aspects which influence the results of the subsoil-structure interaction analysis. The experimental measurement of stress and strain and monitoring of stress-strain relations by interaction of foundation structures with subsoil are also performed at the Faculty of Civil Engineering, VŠB-TU Ostrava. Numerical analyses of contact task was made with FEM. The test sample for the task was a steel-fibre reinforced concrete foundation slab model loaded during experimental loading test. The calculated values of the subsidence do not correspond to the measured values of foundation subsidence of existing buildings, or values measured during the experiments. Results of the solutions are also different and depend on the choice of the model of the subsoil. Using several FEM software tools were made numerical analyses. Results of FEM analyses were also confronted with the values measured during the experiment.

Determination of Material Parameters for Nonlinear Analysis of Reinforced Concrete

The aim of the paper is a nonlinear analysis of concrete structures. For these type of tasks is an important suitable choice of model input parameters and concrete. Especially if the analysis is preceding the results of an experiment, which can determine the exact properties of concrete. The following properties of concrete are needed for nonlinear analysis: tensile strength and compressive strength of concrete. There are more procedures how to determine some unknown input parameters. The paper presents some approaches to calculating and selecting parameters, which are based primarily on the recommendations of the Model Code and professional articles. Specifically, the numerical analysis performed in our developed program which allows observing a nonlinear behaviour of concrete at loading case.

Punching Resistance Verification of Footings

The presented paper will bring new aspects of punching resistance verification of concrete column footings and foundation slabs coming from influence of ground stresses distribution on punching verification of flat footings and from new design criteria which depend on the maximum punching resistance defined from crushing of concrete struts (a criterion for limitation of maximum shear forces at the vicinity of the columns) and on the maximum punching resistance defined from shear-bending failure with shear reinforcement, limited by coefficient kmax.

Numerical Modeling of the Interaction of Subsoil and Reinforced Concrete Slab

The influence of the physically-nonlinear behavior of the structure and interaction between the upper structure and foundation are the aspects which influence the results of the subsoil-structure interaction analysis. The aim of the application of computational model is to determine the most apposite distribution of stress and deformation due the contact stress in the footing bottom. This contact stress is especially dependent to the load. It also depends on the subsoil stiffness, upper structure stiffness and foundation stiffness too. Numerical analyses of contact task were made with FEM. The test sample for the task was a reinforced concrete foundation slab model loaded during experimental loading test. The subsoil is heterogeneous. Its properties are different from the idealized behavior of the linear elastic isotropic homogeneous material. Application of inhomogeneous half-space allows better capture the subsoil behavior because of increasing modulus of deformability with increasing depth of subsoil model. Results of FEM analyses were also confronted with the values measured during the experiment.

Software for Design and Assessment of Rotationally Symmetrically Loaded Reinforced Concrete Slabs in the Shape of Circle or Ring

The subject of this paper is an universal software for reinforced concrete annular and circular slabs reinforced in the radial and tangential direction. Such slabs are used for roof and ceiling structures of buildings. The software can be used for design and assessment of rotationally symmetrically loaded annular and circular reinforced concrete slabs with arbitrary supports and span. Based on users choice, the software proposes solutions to not only meet all the design principles, but especially ultimate limit state and serviceability limit state.