Martina Smirakova

Bitumen Sliding Joints for Friction Elimination in Footing Bottom

Use of a sliding joint is an effective method to decrease the stress in foundation structure where there is a horizontal deformation of subsoil (areas afflicted with underground mining) or horizontal deformation of a foundation structure (pre-stressed foundations, creep, shrinkage, temperature deformation). A convenient material for a sliding joint is a bitumen asphalt belt. Experiments for different types of bitumen belts were undertaken at the Faculty of Civil Engineering - VSB Technical University of Ostrava in 2008. Since 2011 an extension of the 2008 experiments has been in progress and the shear resistance of a slide joint is being tested as a function of temperature in a temperature controlled room. In this paper experimental results of temperature dependant shear resistance are presented. The result of the experiments should be the sliding joint shear resistance as a function of deformation velocity and temperature. This relationship is used for numerical analysis of stress/strain relation between foundation structure and subsoil.

Comparison of the Shear Resistance in the Sliding Joint between Asphalt Belts and Modern PVC Foils

This paper deals with sliding joint in the foundation structure. Application of sliding joint into foundation structure is an effective method to reduce effect of horizontal deformation of foundations. These can arise from effect of undermining or from shrinkage or creep of concrete. A different material can be used to create sliding joint but some are advantageous and some are not. It is often used an asphalt belt or newly different modern foils are used too. Different types of asphalt belts are tested at Faculty of Civil Engineering at different loads and at different temperatures. Some foils are tested too. The effect of ambient temperature is monitored to better description of temperature dependency of asphalt belts. Long-term goal of this research is to simplify process of design buildings with sliding joint and to help designer with right choice of the most advantageous material.

Behavior of Selected Materials to Create Sliding Joint in the Foundation Structure

Some foundation structures can be loaded with horizontal stress, for example pre-stressed foundation structures or structures on undermining areas. Then it is necessary to solute their effects, because they can have very significant effect on the building. When it is spoken about the foundation structures which are loaded with horizontal stress then it is spoken about two possibilities of this loading. In the first case there are horizontal deformations in the structure and in the second case these deformations can arise in the subsoil. In both of them it can be used the method with using sliding joint to increase of shear stress between foundation structure and subsoil. Asphalt belt is often used to create this sliding joint. At the faculty of Civil Engineering some materials are tested to better knowledge of asphalt belts properties and to more precise design and calculation of sliding joint.

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.

Influence of Various Amount of Steel Fibers on Load Capacity and Strain in Model Foundation Slab

In the paper the brief introduction of soil-structure interaction research at VSB TU Ostrava is presented. Currently resistance of model foundation slabs made of steel fibre reinforced concrete exposed to vertical load is tested. Strain gauge measurement is described and particular results are presented. Strain gauge measurement efficiency is discussed.

Analysis of Model Foundation Slab Focused on Strain Gauge Measurement

Interaction analysis between foundation structure and subsoil and credential assessment of stress in the subsoil and internal forces in foundation structure are discussed in research conferences and scientific journals in the long term. Since 2012 research team at Faculty of civil engineering VSB - TU Ostrava has tested a few slabs with dimensions 2 x 2 m with thickness from 0.12 to 0.2 m. Complex testing comprises measurement of slab deformations, stress in the subsoil and measurement of stress in foundation slab using strain gauges. Slabs were made of plain concrete, reinforced concrete, pre-stressed concrete and fibre concrete. In the paper there are particular test results of stress measured in the foundation structure. Measured values are compared with calculated values. Strain gauge measurement efficiency and optimisation is discussed.

Design of Bitumen Asphalt Belt Sliding Joint Based on Experiment Results

Foundation structures are usually exposed to dominant vertical load. However, in some cases there is also significant value of horizontal load caused e.g. by horizontal terrain deformation on areas attached with underground mining or by horizontal deformation of foundation structure due to pre-stressing, creep, shrinkage, and temperature variation. Through the friction between subsoil and foundations, the foundation structure must resist significant normal forces. The idea of sliding joints between subsoil and foundation structure, which eliminates the friction in footing bottom, comes from the 1970’s. The bitumen asphalt belt given rheological properties has been proven as an effective material for sliding joints. In the paper there are test results of shear resistance of currently used asphalt belts. The test results are used for subsoil shear stress analysis in model example of strip foundation. Shear resistance is calculated according to Czech code for designing buildings on undermined area and also using advanced FEM analysis.

Testing and Modelling of Concrete Pile Foundations

Foundation of building on concrete piles is often used when it is necessary to carry the load into larger depth as by common foundation. Bearing capacity of piles or piled raft foundation is wide area to research. This paper deals with experimental load test of concrete pile and with their numerical modelling. Several types of foundation construction were tested and two kinds will be presented and compared in this paper - reinforced concrete foundation slab and raft foundation (made of reinforced concrete foundation slab supported by drilled reinforced concrete pilot). These types of foundation constructions were constructed as models, in a reduced scale, approx. 1:10. The size had to be adjusted due to limited capacity of the testing equipment and financial reasons. Except measuring of the foundation behaviour, there was also carried out measurement of the adjacent terrain.The aim of this paper is to compare the behaviour of rigid slab and the piled raft. The measurement results will be then compared with the results of numerical modelling.

Frequent Failures of FRC Industrial Floors

Floors in industrial buildings are often loaded with heavy traffic or stored material. For this reason floors are often created by fiber-reinforced concrete. Fibers contribute to larger impact - or abrasion resistance. The issue of design of fiber concrete slabs is quite complicated. Poorly designed layer structure under slabs or poorly subsoil can have very important effect of result properties and create the first group of source of problem. The second group of causes of problems is real implementation of concrete slab primarily the amount of fibers and correct and even placement. If amount or placement of fibers are incorrectly then significant failure can arise. This paper deals with frequently failures of FRC floors in practice. It will be described several buildings in which were fiber concrete slab constructed and where some failure arose. It will be presented what kind and what range of failure arose. Causes of failures will be also described in this paper. Also possible solution of problem will be designed if it exist.